## The Nature of the Ozone Air Quality Problem in the O zone Transport R egion: A Conceptual Desc ription

Prepared fo r the Ozone Trans port C om m is si on

Prepared b y NES CAUM Bo ston, MA

Final October 2006

Contributing A uthors

Tom Do wns, Maine Depart ment of Environm enta l Protection Richard Fields, Mas sachusetts Departm ent of Environ ment al P rotection

Prof. Robert H udson, Universit y of M ar yl an d I ya d K heirbek, NESC AUM Gar y Klei man, NESCA UM Paul Miller, NE SCAU M Leah Weiss, NESCA UMAc kno wl edgem en ts

NESCA UM thanks the Mid-Atlantic Regional Air M anage ment A ssociation for providing the foundational basis of this report.

NESCA UM also thanks the following people for their comm en ts and input during the develop men t of this report:

Tad Aburn, M ar yl an d Departm ent of the Environ ment Michael Geigert, Connecticut Departm ent of Environ ment al P rotection Kurt Kebschull, Connecticut D epart ment of Environm enta l Protection Tonalee Key , Ne w Jersey Departm ent of Environ men tal P rotection Moham me d A. Ma

jeed, D elaware Depart ment of Natural Resources and Environm ental Conservation Charles Pietarinen, New Jer se y Departmen t of Environ menta l Protection Jeff Underhill, New Hampshire Depart ment of Environmen tal Services David Wackter, Connecticut Departmen t of Environ menta l Protection Martha Webster, M aine Departm ent of Environ men tal P rotection Dann y Wong, New Jersey Departmen t of Environ ment al Protection Jung-Hun Woo, NESC AUM Michael Woodm an, Mar yl and Departmen t of the Environmen t

ii

### T A B L E O F C O N T E N T S

Executiv e Summ ar y

............................................................................................................. v 1.Introduction

....................................................................................................................... 1 1.1.Background

................................................................................................................ 1 1.2.Ozone form ation

........................................................................................................ 2 1.3.Spatial pattern of ozone episodes in the OTR

............................................................ 3 1.4.The regional extent

of the ozone proble m in the OTR

.............................................. 4 1.5.Ozone trends in the OTR

........................................................................................... 6 1.6.History of ozone transport science

............................................................................. 7 1.6.1.From the 1970s to the N ational Research Council report, 1991

......................... 7 1.6.2.Ozone Transport As sessment G roup (OTAG) 1995-1997

................................. 8 1.6.3.Northeast O xidant and Particle Stud y (NE-OP S) 1998-2002

............................. 9 1.6.4.NAR STO 2000

.................................................................................................. 11 1.6.5.New England Air Q ualit y Study ( NEAQS) 2002-2004

.................................... 13 1.6.6.Regional Atmospher ic Measuremen t, Modeling, and Prediction Program (RAM MPP) 2003

....................................................................................................... 14 1.7.Sum mar

y

.................................................................................................................. 14 2.Meteorolog y and Evolution of Ozone Episodes in the Ozone Transport Region

............. 1 2.1.Large- scale weather

patterns

...................................................................................... 1 2.2.Meteorologica l mix ing processes

.............................................................................. 2 2.2.1.Nocturnal inversions

........................................................................................... 3 2.2.2.Subsidence inversions

......................................................................................... 3 2.3.Meteorologica l transport processes

............................................................................ 3 2.3.1.Introduction

......................................................................................................... 3 2.3.2.Ground level winds

............................................................................................. 5 2.3.3.Mid-level winds: Nocturnal low level jets

.......................................................... 7 2.3.4.Upper level winds: Ozone and precursors aloft

.................................................. 9 2.4.Atmospheri c mode ling of regional ozone transport

................................................. 11 2.5.Sum mar

y

.................................................................................................................. 14 3.Ozone-form ing Pollutant E missions

................................................................................. 1 3.1.Em issions inventor y characteristi cs in the OTR

........................................................ 1 3.1.1.Volatile organic compounds (V OCs)

.................................................................. 1 3.1.2.Oxides of nitrogen (N OX)

.................................................................................. 2 3.2.Em issions inventor y characteristi cs outside the OTR

............................................... 5 3.3.Are NO X or VOC control strategies most effective at reducing ozone?

................... 7 3.4.Sum mar

y

.................................................................................................................... 7 4.What Will It Take to Clean the Air? – Linking the Science to P olic y

.............................. 1 4.1.The three phases of a bad ozone day and the ozone reservoir

................................... 1 4.2.Chronolog y of an ozone episode – Augu st 2002

....................................................... 3 4.3.Clean Air Act provisions

........................................................................................... 9 4.4.Past regional efforts

................................................................................................. 10 4.5.Sum mar

y : Building upon success

............................................................................ 11 Appendix A: USEPA G uidance on Ozone Conceptual Description

.................................... 1 Appendix B:Ozone pattern classificat ions in the OTR

........................................................ 1 Appendix C:Exceedance day s by monitor in the OTR

........................................................ 1 Appendix D:8-hour ozone design values in the OTR, 1997-2005

..................................... 17

iiiAppendix E:The sea breeze and flow over the ocean in-depth

............................................ 1

Appendix F: Observed nocturnal low level j et across the OTR, July 2002

.......................... 1 Appendix G:Contributions to the ozone reservoir

............................................................... 1



### F I G U R E S Figure 1

- 1. Conceptual picture of ozone format ion in the atmospher e

............................... 3 Figure 1

- 2. Map of 8-hour ozone baseline design values in the OTR

................................. 5 Figure 1

- 3. Trends in 8-hour ozone in the OTR 1997-2005

................................................ 6 Figure 1

- 4. Conceptual picture of different transport regi mes contributing to ozone episodes in the OTR

........................................................................................................... 12 Figure 2

- 5. Temper ature profile taken over Albany
, NY , on Septe mber 1, 2006 at 7 a.m. eastern standard time

............................................................................................................ 2 Figure 2

- 6. Schemat ic of a ty pi ca l weather

pattern associated with s evere ozone episodes in the OTR

............................................................................................................................ 4 Figure 2

- 7. Illustration of a sea breeze and a land breeze

.................................................... 5 Figure 2

- 8. A verage 2000 – 2002 wind direction frequency associated with elevatedonehour ozone levels in coastal Maine

...................................................................................... 6 Figure 2

- 9. Ozonesonde measure me nts on August 5, 2005 of elevated ozone concentrat ions in a nocturnal low level j et above Beltsvill e, MD

...................................... 9 Figure 2

- 10. Altitude profiles for ozone, carbon monoxide, N OY, and S O2 taken on July 15, 1995

...................................................................................................................... 10 Figure 2

- 11. O bserved vertical ozone profile measured above Poughkeepsie, N Y at about 4 a.m. EST on July 14, 1995

.............................................................................................. 11 Figure 3

- 12. 2002 M ANE-VU state VOC inventories in the OTR

..................................... 2 Figure 3

- 13. State level nitrogen oxides emissions

............................................................. 3 Figure 3

- 14. Plot of moni tored NO X trends in OTR during 1997-2005

............................. 4 Figure 3

- 15. 2002 M ANE-VU state NO X inventories in the OTR

..................................... 5 Figure 4

- 16. Median ozone profiles for morn ing and afternoon flights from 1996 – 2003 1 Figure 4

- 17. H ourl y ozone profiles in the s outhern OTR, Augu st 12, 2002

....................... 2 Figure 4

- 18. H ourl y ozone profiles in the northern OTR, August 12, 2002

........................ 3 Figure 4

- 19. Surface weather maps for August 9-16, 2002

................................................. 6 Figure 4

- 20. H YSPLIT 72-hour back trajectories for A ugust 9-16, 2002

.......................... 7 Figure 4

- 21. Spatiall y interpola ted m aps of maxi mu m 8-hour surface ozone concentrat ions Augu st 9 – 16, 2002

..................................................................................... 8



### T A B L E S Table 2

- 1. USEP A CAIR mode ling results of percent contribution to 8-hour ozone nonattain me nt in OTR counties in 2010 due to transport from up wind states

.................. 12 Table 2

- 2. USEP A CAIR mode ling results of up wind states that make a significant contribution to 8-hour ozone in down wind OTR nonattainm en t counties

........................ 13 Table 3

- 3. Eastern U.S. R POs and their state mem bers

....................................................... 6 Table 3

- 4. VOC emissions in eastern RP Os

........................................................................ 6 Table 3

- 5. NO X em issions in eastern R POs

........................................................................ 7

iv

## Ex ecutive Summary
The Ozone Transport Region (OTR) of the eastern U nited States covers a large

area that is home to over 62 mi llion people living in Connecticut, Delaware, the District of Columb ia, M aine, Mary la nd, M assachusetts, N ew Hampshire, Ne w Jersey , New Y ork, Pennsy lv ani a, Rhode Island, Vermont, and northern Virginia. Each s um me r, the people who live within the OTR are s ubject to episodes of poor air qualit y resulting from ground-level ozone pollution that affects much of the region. D uring severe ozone events, the scale of the proble m can extend be yo nd the OTR’s borders and include over 200,000 square m iles across the eastern U nited States. Contributing to the problem are local sources of air pollution as well as air pollution transported hundreds of mi les from distant sources outside the OTR.
To addres s the ozone problem, the Clean Air Act Amend men ts require states to develop State Imple me nt ation Plans (SI Ps) detailing their approaches for reducing ozone pollution. A s part of this process, states are urged by the U .S. Environm enta l Protection Agency (USEPA) to include in their SIPs a conceptual description of the pollution proble m in their nonattain me nt areas. This document provides the conceptual description of the ozone proble m in the OTR states, consistent with the USEPA’ s guidance.
Since the late 1970 s, a w ealth of infor mation has been collec ted concerning the regional nature of the OTR’s ground-level ozone air qualit y problem. Scientific studies have uncovered a rich comp lexi t y in the interact ion of me teorolog y and topograph y with

ozone format ion and transport. The evolution of severe ozone episodes in the eastern U.S. often begins with the passage of a large high pre ssure area from the Midwest to the midd le or s outhern Atlantic states, w here it as sim ila tes into and becom es an extension of the Atlantic (Bermud a) high pre ssure s ys tem

. D uring its passage east, the air mass
accu mula tes air

pollutants emi tted by large coal- fired power plants and other sources located outside the OTR. Later, sources within the OTR make their own contributions to the air pollution burden. These expansive weather s yste ms favor the format ion of ozone b y creating a vast area of clear skies and high tempera tures. These two prerequisites for abundant ozone formation are further compounded by a circulat ion pattern favorable for pollution transport over large distances. In the w orst cases, the high pressure s yst em s stall

over the eastern United States for da ys, creating ozone episodes of strong intensit y and long duration. One transport mechan ism that has fairl y recentl y com e to light and can pla y a ke y role in moving pollution long distances is the nocturnal low level jet. The j et is a regional scale phenomenon of higher wind speeds that often forms during ozone events a few hundred meters above the ground ju st above the stable nocturnal boundary la ye r. It can

conve y air pollution several hundreds of m iles overnight from the southwest to the northeast, directl y in line with the major population centers of the Northeast Corridor stretching from Washington, D C to Bo ston, Ma ssachusetts. The nocturnal low level j et

can extend the entire length of the corridor from Virginia to Maine, and has been observed as far s outh as G eorgia. It can thus be a transport mech anism for bringing ozone and other air

pollutants into the OTR from outside the region, as well as move locall y formed air pollution from one part of the OTR to another.

vOther transport mech anis ms occurover small er scales. These include land, sea,

mount ain, and valle y breezes that can selective l y affect relative l y local areas. They pla y a vital role in drawing ozone-laden air into some areas, such as coastal Maine, that are far

remov ed from m ajor source regions.
With the kno wledge of the different transport scales into and within the OTR, a conceptual picture of bad ozone day s emerges. A fter s unset, the ground cools fa ster than the air above it, creating a nocturnal te mpera ture inversion. This stable boundar y la y er extends from the ground to onl y a few hundred meters in altitude. A bove this la ye r, a nocturnal low level j et can formwith higher velocit y wind s relativ e to the surrounding air. It forms from the fairl y abrupt removal of frictional forces induced by the ground that would otherwise slo w the wind. Ab sent this friction, wind s at this height are free to acceler ate, forming the nocturnal low level jet. Ozone above the stable nocturnal inversion lay er is likewise cut off fromthe ground, and thus it is not sub ject to re moval on surfaces or che mic al destruction from low level emissions. Ozone in high concentrat ions can be entrained in the nocturnal low level jet and transported several hundred kilome ters down wind overnight. The nextmorning as the sun heats the Earth’s surface, the nocturnal boundar y lay er begins to break up, and the ozone transported overnight mix es do wn to the surface w here concentrations rise rapidl y, partl y from mix ing and partly from ozone generated locall y. B y the afternoon, abundant sunshine comb ined with warm temp eratur es promotes additiona l photoche mic al production of

ozone from local em issions. A s a result, ozone concentrat ions reach their maxim um levels through the combin ed effects of local and transported pollution.
Ozone mov ing over wateris, like ozone aloft, isolated from destructive forces. When ozone gets transported into coastal regions b y ba y, lake, and sea breezes arising from afternoon te mpera ture contrasts between the land and water, it can arrive highly concentrat ed. During severe ozone episodes associated with high pressure sy ste ms, these mul tipl e transport features are embedd ed within a large ozone reservoir arriving from source regions to the s outh and we st of the OTR. Thus a severe ozone episode can contain ele men ts of long range air pollution transport from outside the OTR, regional scale transport within the OTR from channeled flow s in nocturnal low level j ets, and local transport along coastal s hores due to bay
, lake, and sea breezes.
From this conceptual description of ozone format ion and transport into and within the OTR, air qualit y planners need to develop an understanding of what it will take to clean the air

in the OTR. Weather is alway s changing, s o ever y ozone episode is unique in its specific details. The relative influences of the transport pathway s and local

em issions vary by hour and da y during the course of an ozone episode and between episodes. The small er scale weather patterns that affect pollution accumu lat ion and its transport underscore the import ance of local (in-state) controls for emissions of nitrogen oxides ( NO X ) and volatile organic compounds (V OCs), the main precursors of ozone forma tion in the at mosphere. Larger s yn optic scale weather patterns, and pollution patterns associated with the m, support the need for NO X controls across the broader eastern United States. Studies and characteriz ations of nocturnal low level j ets also support the need for local and regional controls on N O X and VO C sources as locall y generated and transported pollution can both be entrained in nocturnal low level jets

viformed during nightti me hours. The presence of land, sea, mounta in, and valle y breezes

indicat e that there are unique aspects of pollution accumu lation and transport that are
area- specific and will warrant policy responses at the local and regional levels bey ond a
one- size-fits-all approach.
The mix of emission controls is also import ant. Regional ozone forma tion is prim aril y due to NO X , but VO Cs are also import ant because the y influence how efficien tl y ozone is produced b y NO X , particularl y within urban centers. While reductions in anthropogenic VO Cs will ty pi ca ll y have less of an imp act on the long- range transport of ozone, they can be effective in reducing ozone in urban areas where ozone production

ma y be li mit ed b y

the availabil it y of VOC s. Therefore, a combina tion of localized V OC reductions in urban centers with additional N O X reductions acros s a larger region will help to reduce ozone and precursors in nonattainm en t areas as well as down wind transport across the entire region.
The recognition that ground-level ozone in the eastern U nited States is a regional proble m requiring a regional s olution marks one of the greatest advances in air

qualit y
man agem en t in the United States. During the 1990s, air qualit y planners began developing and imple me nt ing coordinated regional and local control strategies for NO X and V OC emissions that went be yo nd the previous emph asis on urban-onl y m easures. These measures have resulted in significant i mprovem en ts in air

qualit y across the OTR. Measured NO X emissions and amb ient concentrations have dropped between 1997 and 2005, and the frequenc y and magn itude of ozone exceedances have declined within the OTR. To maint ain the current mom en tum for i mproving air qualit y so that the OTR states

can meet their attainm en t deadlines, there continues to be a need for more regional NO X reductions coupled with appropriate local N O X and V OC controls.

viiThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



## 1. INT RODUC TI ON

1.1. Bac kground Ground-level ozone is a persistent public health problem in the Ozone Transport Region (OTR), a large geographical area that is home to over 62 mi llion people living in Connecticu t, Delaware, the District of Columb ia, Maine, Mary la nd, Massachusetts, New Hampshire, Ne w Jersey , New Y ork, Penns yl van ia, Rhode I sland, Vermont, and northern Virginia. Breathing ozone in the air harms lung tissue, and creates the risk of perman entl y dam aging the lungs. It reduces lung function, making breathing more difficult and causing s hortness of breath. It aggravates existing asth mati c conditions, thus potential l y triggering a sth ma

attacks that send children and others suffering from the disease to hospital em ergenc y rooms. O zone places at particular risk those with preexisting respirator y illnesses, s uch a s e mph ys em a and bronchitis, and it ma y reduce the body ’s abilit y to fight off bacterial infections in the respirator y sy ste m. Ground-level ozone also affects otherwise health y children and adults w ho are very active, either at work or at pla y, during ti mes of high ozone levels ( USEPA, 1999). In addition, recent evidence suggests that s hort- term ozone exposure has potentia l cardiovascular effects that ma y increase the risk of heart attack, stroke, or even death ( USEPA, 2006).
The Clean Air Act requires states that have areas designated “ nonattain me nt” of the ozone National Ambient Air Qualit y Standard (N AAQ S) to s ubm it State Impl em en tat ion Plans (SIP s) demonstr ating ho w the y plan to attain the ozone NA AQS. The SI Ps must also include regulations that will yi el d the necessar y em ission reductions to attain the national ozone health standard. As part of the SI P process, the U .S. Environ ment al Protection A genc y (U SEPA) urges states to include a conceptual description of the pollution proble m in their nonattainm ent areas. The U SEPA has provided guidance on developing a conceptua l description, which is contained in Chapter 8 of the documen t “G uidance on the U se of Models and Other A nal ys es in Attain men t Demonstrat ions for the 8-hour O zone N AA QS” (EPA-454/R-05-002, October 2005) ( Appendix A of this report reproduces Chapter 8 of the USEPA guidance docum ent). a This document provides the conceptual description of the ozone problem in the OTR states, consistent with the USEP A’s guidance. In the guidance, the USEP A

reco mm ends addressing three questions to help define the ozone proble m in a nonattain me nt area: (1) I s regional transport an i mportan t factor? (2) What ty pe s of

me teorolog ical episodes lead to high ozone ? (3) Is ozone limi ted b y availab ili t y of volatil e organic compounds, nitrogen oxides, or comb inat ions of the two, and therefore which s ource categories ma y be most impor tant to control? This report addresses these questions, a s well as provides some in- depth data and anal y ses that can assist states in developing conceptua l descriptions tailored to their s pecific areas, where appropriate.

a At the time of this writing, t he USE PA was incorporating Section 8 of the 8- hour oz one guidance in to a

new USE PA guidance document covering o zone, P M 2.5 , and region al haze. The new guidanc e is in Section 11 of

Draft3.2 “Guidance on the Use of Models and other Anal ys es for Demonstrating Attainment of Air Quality Goals for

Ozone, P M 2.5 , and Regional Haze,” U.S. EPA, (Draft 3.2 – September 2006), available at http: //www.epa. gov/ttn/scram/ guidanc e_sip.htm#pm2.5 (acc essed Oct. 5, 2006). The newer guidanc e, when finali zed, may differ in some respects from t

he te xt given in Sect ion 8 of t he earlier ozone guidanc e.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2



### 1.2. Ozone form ation Ground-level ozone is formed in the at mosphere through a series of compl ex che mica l reactions involving sunlight, warm te mpera tures, nitrogen oxides (N O X ) and volatil e organic compounds (VOC s). Figure 1-1 is a conceptual picture of the e mission sources and conditions contributing to ozone formation in the atmosphere. There are natural (biogenic) s ources of NO X , s uch as formation by soil mi crobes, lightening, and forest fires, but the dominant N O X sources in the eastern U nited States arise from human activi ties, particul arl y the burning of fossil fuels in cars, trucks, power plants, and other combust ion sources (M ARAM A, 2005).
In contrast to NO X s ources, there are significant biogenic s ources of VOC s in the eastern United States that can play an i mportan t contributing role in ozone format ion. Isoprene, a highly reactiv e natural VOC emit ted t yp ic al l y b y deciduous trees such as oak, is an importan t ozone precursor across large parts of the East. Isoprene emissions t yp ic al l y increase with te mpera ture up to a point before high tempera tures tend to shut off

em issions a s leaf

stoma ta (pores) close to reduce water loss. The tendenc y for increasing isoprene emissions with increasing te mpera tures (up to a point) coincides with the te mpera ture and s unlight conditions favorable for increased ozone production (MAR AMA, 2005).
Human- caused (anthropogenic) VOC emissions are i mportan t and ma y domina te the V OC em issions b y

m ass (weight) in an urban area, even though natural s ources domin ate in the overall region. Some anthropogenic VOC s, such as benzene, are toxic, and ma y increase risks of cancer or lead to other adverse health effects in addition to helping form ozone (M ARAM A, 2005).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

Figure 1

- 1 . Conceptual picture o f ozone f orm at ion in the atm os phere

Picture provided b y

the Mar yl an d Department of the Env ironment. The relationship between the relative i mportanc e of NO X and VO C em issions in producing ozone is comp lex. The relative ratio of N O X and V OC levels in the local at mosphere can affect the efficienc y of local urban ozone production, and this can var y b y ti me (hour or day ) at the same urban location, as well as acros s locations within the

same urban area. High N O X concentrat ions relative to VO C levels ma y hinder ozone production through the destruction of ozone by N O X (somet im es called “ NO X scavenging”). The same NO X , ho wever, when diluted relative to VOC s through the downwind transport and dispersal of a pollution plume, will promo te ozone format ion elsewhere.



### 1.3. Spat ial pat tern o f ozone episodes in t he OTR The day

- to-da y pattern of ground-level ozone varies according to m eteorolog ica l variables that include, but are not limi ted to, sunlight, air te mperatur e, wind speed, and wind direction. Generall y within the OTR, one would expect elevat ed ozone to occur

more frequentl y in southernmost areas, where s olar elevation angles are greater and cold frontal passages are fewer. A glance at monthl y composit e maps (for exa mple, J ul yAugust 2002) at the USEP A AIRN OW w ebsite seems to confirm this ( http://www.epa.gov/ airnow/ne ma pselec t.ht ml ). On some da ys , however, one notes that the highest ozone levels s hift northward to mainl y affect the northern part of the OTR. Other s hifts are apparent

between coastal and interior areas. This variability of the dail y ozone pattern is tied to variations in the at mosphere’s circula tions over a range of scales, and ho w geographic features influence theseThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

circula tions. These features can include boundaries between land and sea, and the influence of the Appalachian M ountains on winds to their east over the Atlantic Coastal Plain.
For the OTR, Stoeckenius and Kemball- Cook (2005) have identifi ed five general

ozone patterns: (1) high ozone throughout the OTR; (2) high ozone confined to the extre me s outheastern OTR; (3) high ozone along the I-95 corridor and northern New England; (4) high ozone in the western OTR; and (5) generall y low ozone throughout the OTR. However, not all ozone episodes necessaril y neatl y fit into one of the five general patterns as dail y conditions will vary and a given ozone episode ma y have characterist ics that fall across several class ty pe s. These five general patterns, however, are a useful classificat ion schem e for characteri zing ho w representativ e an historical ozone episode is for possible u se in air qualit y planning efforts. A ppendix B presents the descriptions of the five general ozone patterns and their met eorologi cal attributes as developed b y Stoeckenius and Kemba ll- Cook (2005).



### 1.4. The regional ex tent of t he ozone proble m in t he OTR Air moni toring demonstrat es that areas with ozone problems in the OTR do not exist in isolation. The map of Figure 1-2 show s an extensive pattern of closel y ad jacent

ozone nonattainm en t in areas throughout the OTR. The 8-hour ozone baseline design values (defined in the figure caption) at the mon itoring sites sho wn in the figure indicate extensive areas throughout the OTR with man y monitors having values above the 8-hour

ozone N AA QS of 0.08 ppm. In practice, this correspond s to levels equal to or greater than 0.085 ppm (equivalent to 85 ppb). The map also s hows that man y moni tors outside the designated nonattainm en t areas of the OTR also record elevated ozone concentrat ions approaching the 8-hour ozone NA AQS (i.e., 75-84.9 ppb), even if not violat ing it. The

man y monitor ing locations across that OTR measuring elevated ozone levels that approach or exceed the 8-hour ozone NA AQS give a strong indicat ion of the regional nature of the OTR’ s ozone problem.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

Figure 1

- 2 . Map of

8-hour ozone baseline de sign values in the OTR

Note: A monitor’s baseline design value is the average of the three design values (3- ye ar averages of the 4th ma xim um 8- hour ozone level) for the set of ye ars 2000- 2002, 2001- 2003, and 2002- 2004

. The fi gure shows the regional nature of ozon e levels in the OTR, w ith a number of closely adjacent non attainment areas (baseline design values ≥ 85 ppb) along with a broad er region of elevated regional ozone (e .g., bas eline design values ≥ 75 ppb) (figure b y Micha el Geigert, Connecticut Department of Environmental Protection).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6



### 1.5. Ozone trends in the OTR The number

of 8-hour ozone exceedance day s vary ye ar

- to- ye ar in the OTR, which is largel y driven b y variations in meteoro log y. During warmer s um me rs conducive for ozone format ion, the number of exceedance day s at individua l moni tors in nonattain me nt areas of the OTR has been frequent, ty pi ca ll y with 10 or more day s above the 8-hour ozone NA AQS during the course of the sum me r. Figure 1-3 display s the variation in exceedance day s w hen collectiv el y considering all moni toring sites across the OTR since 1997. The figure also includes a line indicat ing the trend in the max im um 8- hour ozone concentrations observed in the OTR each y ea r. The variation in exceedance da ys from ye ar

- to-y ea r makes it difficult to discern a clear trend, although there is some hint that the numb er of exceedance day s ma y be declining in recent y ea rs. There appears to be a stronger indicat ion of a declining maxi mu m 8-hour ozone concentrat ion in the OTR since 1997, although the max im um concentration rema ins well above the 8-hour

ozone N AA QS. This reflects the imp act of numerous control strategies impl em en ted locall y , regionall y, and nationall y to reduce e missions of the precursor pollutan ts that contribute to ozone formation in the atmosphere.

Figure 1

- 3 . Trend s in 8-h our ozone in t he OTR 1997-2005

1997

- 2 0 05 OZON E SE AS ON 8

- H OUR OZ ONE EX CE EDA NC E DA Y S AN D MAXI MU M 8

- hr OZO N E C O N CE NT RA T ION T REN DS I N THE OT R

0 10 20 30 40 50 60 70 80 90

199 7 1998 1 999 2000 200 1 2002 20 03 2004 2005
YEA R#8-hrOZONE EXCEEDANCEDAYS

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.168-HOURCONCENTRATION(ppm)

# EX C E EDANC E DAYS MA X I M U M 8

- hr OZO NE 8

- ho u r o z on e N A A QS l ev el

0.08 5 1997

- 2 0 05 OZON E SE AS ON 8

- H OUR OZ ONE EX CE EDA NC E DA Y S AN D MAXI MU M 8

- hr OZO N E C O N CE NT RA T ION T REN DS I N THE OT R

0 10 20 30 40 50 60 70 80 90

199 7 1998 1 999 2000 200 1 2002 20 03 2004 2005
YEA R#8-hrOZONE EXCEEDANCEDAYS

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.168-HOURCONCENTRATION(ppm)

# EX C E EDANC E DAYS MA X I M U M 8

- hr OZO NE 8

- ho u r o z on e N A A QS l ev el

0.08 5The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 7

Note: The bars c orrespond to the number of 8- hour ozone exceedance da ys per y ea r. The upp er blue line indicates the trend in maxi mu m 8- hour o zone concentrations in th e OTR during 1997- 2005 . The lo wer red horizontal lin e indicates th e level of

the 8- hour ozone NAAQS (functionally 0 .085 ppm). (Figure created b y Tom Do wns, Maine Dept. of Environmental Protection .) The tables in Appendix C contain the frequenc y of ozone exceedanc e da ys for individual monitors in the OTR states from 1997 to 2005. A ppendix D contains tables for the 8-hour ozone design values recorded at ozone monitors in the OTR during 1997- 2005. These tables give an indicat ion of the number of mon itors in the OTR since 1997 that have exceeded

the 8-hour N AA QS of 85 ppb (equal to 0.085 ppm in the tables of Appendix D ) at s om e point in ti me.


### 1.6. History of ozone transport science

1.6.1. From t he 1970s t o the Na tional Research Council report, 1991 Research studies conducted in the 1970s gave some of the earliest indications that pollution transport pla ys an importan t role in contributing to air pollution problems in the OTR. An aircraft stud y

in the summ er of 1979 tracked a mass of ozone- laden air and its precursors leaving central O hio, cros sing the length of Pennsy lv ania, and entering the Northeast Corridor where it contributed upwards of 90 ppb to early morn ing ozone concentrat ions in the OTR prior to local ozone forma tion from local emissions (Clarke & Ching, 1983). Wolff and Lio y (1980) described a “river of ozone” extending from the Gulf Coast through the Midwest and into New England. A numb er of earl y studies also docum ented the role of large coal- fired power plants in forming significant amoun ts of

ozone pollution that traveled far do wnwind from the power plant source and contributed to a large elevated

background of regional ozone ( Davis et al. , 1974; Miller et al. , 1978; Gillani & Wilson, 1980; Gillani et al. , 1981; White et al. , 1983). Section 2 below describes in more depth the ob served met eorologi cal proces ses identifi ed as the ozone transport mechan isms import ant for the OTR. On a regional scale, NO X em issions within areas of high V OC em issions, s uch as forested regions rich in isoprene, will produce elevated levels of ozone. A number of studies have now established that regional ozone forma tion over the eastern United States is li mit ed prim aril y by the suppl y of anthropogenic N O X , with anthropogenic VO Cs having less regional influence comp ared to their potential urban influence. This is due to the presence of significant amounts of natural V OCs across broad areas of the eastern United States (Trainer et al. , 1987; Chame ides et al. , 1988; Sillman et al. , 1990; McKeen et al. , 1991; Chameid es et al. , 1992; Trainer et al. , 1993; Jacob et al. , 1993).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 8

The presence of disper sed N O X em issions s ources, such as coal- fired po wer plants, in rural regions rich in isoprene and other natural VOC emissions from trees and other vegetation often leads to elevated regional ozone during the summ er months. This

ozone can then be transported into urban areas where it contributes to high background concentrat ions during the earl y morning hours before local production of ozone occurs from local precursor emissions (both N O X and VO Cs). In 1991, a N ational Research Council (NRC) com mi tt ee, s yn thesiz ing the best availab le inform ation at the ti me on ozone format ion and transport in the eastern U nited States, reported ( NRC, 1991): High ozone episodes las t from 3-4 da ys on aver ag e, occur as many as 7- 10 t imes a ye ar , and are of larg e spatial scale: >600,000 km 2 . Ma ximu m values of non- urban ozone commonly e xceed 90 ppb during these episodes, compared with averag e daily ma xi mum values of 60 ppb in sum mer. An urban area need contribute an increment of on l y 30 ppb

over the region al backg round during a h igh ozone episode t o cause a vio lation of t he National Amb ient Air Quality S tandard (NAAQS) i n a downwind area. ... Given the

re gional nature of the ozone problem in the eastern Uni ted S tates, a regional m odel i s needed t o develop control strategies for individual urban areas.
[Note: The NRC discussion was in the contex t of t he o zone NAAQS at the t ime of t he NRC report, which was 0.12 ppm (120 ppb) avera ge d over one hour.]

The observed ozone s patial scale of >600,000 km 2 ( >200,000 square m iles) is comp arable to the combin ed size of K entuck y , Ohio, West Virginia, Penns yl van ia, Mar yl and, Ne w York, and New Jer se y. A dditional field studies and mode ling efforts since the NRC report (described below) have reinforced its ba sic findings and provide a consistent and coherent

bod y of evidence for transport throughout the eastern United States.



### 1.6.2. Ozone Transport Asses s me nt Group (OTAG) 1995 -1997 The increasing regulator y focus on broader regional approaches to ozone control be yo nd the OTR began with the O zone Transport As sessment G roup (OTAG) in 1995. OTAG wa s a partnership between the U SEPA, the Environ ment al Council of the States (ECOS), state and federal governm ent officials, industry organizations, and environ ment al groups. OTA G’s goal wa s “to develop an as sessment of and consensus agree ment for strategies to reduce ground-level ozone and its precursors in the eastern United States” ( OTAG, 1997a). The effort assessed transport of ground-level ozone across state boundaries in the 37-state OTAG region and developed a set of

reco mm enda tions to the USEP A. OTAG comple ted its w ork in 1997.
OTAG s upported a significant modeling effort of four regional ozone episodes across the eastern United States. OT AG’s Regional and Urban Scale M odeling Workgroup found that on a regional scale, modeled N O X reductions produced widespread

ozone decreases across the eastern U nited States with li mited ozone increases generall y confined to some urban areas. Also on a regional scale, VOC reductions resulted in li mit ed ozone decreases generall y confined to urban areas ( OTAG, 1997b).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 9

The OTA G Air Qualit y Analy si s Workgroup provided additional ob servationa l and other anal yt ic al results to inform model interpretat ion and the developm ent of OT AG

reco mm enda tions. Among its man y finding, this Workgroup observed:

L ow wind speeds (< 3 m/ sec) enable t he accumulation of

o zone near

local source areas. High winds (> 6 m

/sec) reduce the concentr ations but contribute t o the l ong- range transport of o zone. The averag e range of ozone transport i mplied from an arra y of d iverse me thods is between 150 miles and 500 miles. However, t he perceived

ran ge depends on whether one considers t he averag e concentr ations (300–500 m iles) or peak concentrations (tens of

m iles at 120 ppb). The relative importance of ozone transport for the attain ment of the new 80 ppb 8-hour standard is l ikel y t o be higher due to the closer

pro ximi t y

of nonattain ment areas. (OTAG, 1997c) Based on the variet y of technica l work performed by mult iple stakeholders during the process, OT AG reached a number of major conclusions (OTAG, 1997d), including:

• Regional NO X reductions are effective in producing o zone benefits; the more NO X reduced, the gr eater the benefit.

• Ozone benefits are gre atest in the subregions where emiss ions reductions are made; the benefits decre ase wi th distance.

• Both elevated (from tal l stacks) and low- level NO X reductions are effective.

• VOC controls are effective i n reducin g ozone locally and are mo st advanta geous t o urban nonattainment areas.

• Air quali t y

data ind icate that ozone is pervasive, that o zone i s transported, and that o zone aloft i s carried over

and transportedfrom one day to the nex t. The technical findings of OTAG w orkgroups were consistent with the model ing and ob servational studies of regional ozone in the eastern U nited States alread y appearing in the scientific literatur e at that time. Through its work, OT AG engaged a broad group outside of the scientifi c
com mu nit y in the discus sion of ozone transport. This brought a greater understanding of the role of ozone transport acros s the eastern U nited States that wa s then translated into air qualit y polic y with the creation of a regional ozone control strateg y focusing on the reduction of NO X emissions from power plants.



### 1.6.3. Northeast Oxidan t and P article Stu dy (NE-OP S) 1998-2002 The Northeast Oxidant and Particle Study ( NE- O PS) began in 1998 as a U SEPA sponsored pro

ject to stud y

air qualit y issues in the N ortheast. The study undertook four major field programs at a fieldsite in northeastern Philadelphia during the summ ers of 1998, 1999, 2001, and 2002. It involved a collaborat ive effort among re search groups from a number

of universities, governmentlaboratories, and representat ives of the electr ic power industr y in an investigation of the interpla y between the me teorolog ica l and chemic al proces ses that lead to air pollution events in the N ortheast. A suite of

me asurem ent techniques at and above the earth’s surface gave a three-di mensional regional scale picture of the atmospher e. The studies found that horizontal transport aloft and vertical mix ing to the surface are ke y factors in controlling the evolution and severit y of air pollution episodes in the Northeast (Philbrick et al. , 2003a).
At the conclusion of the 2002 summ er field study
, the NE-OPS re searchers were able to draw several conclusions about air pollution episodes in P hiladelph ia and draw inferences from this to the conditions in the broader region. These include (Philbrick
et al. , 2003b):The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 10

• Transported air pollu tion from distant sources was a major contributor t o all of t he major sum mer air pol lution episodes observed in the Phi ladelphia area.

• Regional scale meteorolog y i s the major factor controlling t

he magnitude and tim ing of air pollut ion episodes.

• Knowledg e of

how the planetar y boundar y lay er evolves over the course of

a da y i s a critical input for modeling air pollu tant concentrations because it establishes the mi xi ng volume.

• Remote sensing and vertical profil ing techniques are critical for understanding the processes gove rning air pollut ion episodes.

• Ground- based sensors do not detect high levels of ozone that are frequentl y trapped and transported in lay er s above t he surface.

• Horizontal and vertical nighttime transport processes, such as the nocturnal l ow level jets and “d yn ami cal bursting” b events, are frequent contributors of

pol lutants during the major episodes.

• Specific meteorological condit ions are important in catal yzin g the region for development of major air pollu tion episodes.

• Tethered balloon and lidar measurements sug gest a ver y rapid down mi xing of species from the residual boundar y lay er during t he earl y m orning hours that i s too larg e to be accounted for on the basis of NO X reactions alone.

• Sum mer organi c aerosols in P hiladelphia consist of a relatively constant level of primar y organic particulate matter, punctuated b y extreme episodes with h igh levels of secondar y organic aerosol during ozone events. Pr imar y organic particulate mat ter is both b iogenic and anthropog enic in nature, with the relative i mportance fluctuating from da y to day
, and possibly associated m ore strongl y with northwest winds. Secondar y aerosol formation events may be responsible for dramatic increases i n particulate org anic carbon, whi le t he relatively constant contribut ion of primar y sources could make a gre ater contribut ion to annual averag e particulate levels. More

resea rch i s neededto sort out the relative contributions of anthropogeni c and biogenic sources. The findings on nocturnal low level j ets occurring in concert with ozone pollution episodes are particular l y salient for airqualit y planning for the OTR. In 19 of 21 cases where researchers observed nocturnal low level j ets during the NE-OP S 2002 summ er
ca mpaign in the P hiladelph ia area, the y also saw peak 1-hour ozone levels exceeding 100 ppbv. The nocturnal low level jets were capable of transporting pollutants in air parcels over distances of 200 to 400 km. The field me asurem ents indicating that these j ets often occur during periods of large scale stagnation in the region demonstr ate the impor tant role nocturnal low level j ets can play in effectivel y transporting air pollutants during air pollution episodes ( Philbrick et al. , 2003b).
The upper air

ob servations using tethered balloons and lidar indicat ed the presence of high pollutant concentrations trapped in a residual lay er above the s urface, thus preserving the pollutants from destruction closer to the s urface. Ozone, for examp le, when trapped in an upper lay er during nightti me hours is not sub ject to destruction b y NO X scavenging from low-level emission s ources (i.e., cars and trucks) or deposition to surfaces like vegetat ion, hence it is availab le for horizontal transport by nocturnal low level jets. The following da y, it can verticall y transport back down to the surface through “bur sting events” and day ti m e convection. When involving an upper lay er of ozone-laden air horizontall y transported overnight b y a nocturnal low level jet, down ward mixing can increase surface ozone concentrat ions in the morning that is not the result of local ozone production (Philbrick et

al. , 2003b).

b “D yn ami cal bursting” events occur in the earl y morning hours due t o instabil ities in the lower atmosphere causedb y differ ences in wind s peeds at different alt itudes below the la ye r of max imum winds. Bursting events can vertically mi x air downwards to the surfac e (see Phi lbrick et al., 2003b at p. 36).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 11



### 1.6.4. NARSTO 2000
NAR STO (former l y known as the North Amer ican Re search Strateg y for Tropospheric Ozone) produced “ An A sses smen t of Tropospheric Ozone Pollution – A North Ameri can Perspective” in 2000 to provide a polic y
- relevant re search asses smen t of

ozone is sues in N orth America ( NARSTO, 2000). While the N ARSTO A sses smen t is continent al in scope, it encompasses issue s relevant to the OTR, including results from a NAR STO-Northeast (N ARSTO-NE) field campa ign.
Several polic y
- relevant

findings from the N ARSTO A sses smen t are of relevance to the OTR (NAR STO, 2000):

• Available information indicates t hat ozone accumulation is s trongl y influenced b y extended periods of li mited mi xi ng, recir culation of pollu ted air between t he ground

and aloft, and the longran ge transport of ozone and i ts precursors. As a result, air quality management

strate gies require accountin g for

emis sions from d istant as well as local sources.

• L oc al VOC emission reductions ma y be effective i n reducin g ozone in urban centers, while NO X emission reductions become more effective at dis tances removed from urban centers and other major precursor

emissions.

• The presence of biogenic emissions compl icates the management of controllable precurso r emissions and influences the relative importance of VOC and NO X controls.

• The effectiven ess of VOC and NO X control s trate gies is not un iquel y defined b y the l ocation or nature of em issions. It is now recog nized t hat t he relative effectiveness of VOC and NO X controls

ma y chan ge from one l ocation t o another and even from episode to episode at the same l ocation. The N ARSTO A ssessment identif ied the stagnation of s ynop tic scale (>1000 km 2 ) high pres sure s ys tem s as a comm onl y occurring weather event leading to ozone pollution episodes. These sy ste ms are warm air masses associated with weak wind s, subsiding air from above, and strong inversions capping the planetar y boundar y level in the central region of the high. The warm air mass can settle into place for day s to more than a week, and in the eastern U.S. tend to slo wl y track from we st to east during the sum mer. These conditions result in the build up of pollution from local sources with reduced dispersion out of the region. In terms of air qualit y, the overall appearance of such s ys tem s is the presence of numerous local or urban- scale ozone pollution episodes emb edded within a broader regional background of elevat ed ozone concentrations (NAR STO, 2000 at p. 3- 34).
While stagnation impli es little movem en t, the N ARSTO A ssessment found that a variet y of processes can lead to long-range transport of air pollutants that initial l y
accu mula ted in these large- scale stagnation events. O ver time, pollution plum es meander, merg e, and circula te within the high pressure sy ste m. Because of the difference in pressures, pollutant plu mes that eventuall y migrat e to the edges of a high pres sure sys te m get caught in increasing winds at the edge regions, creating more homogeneous regional pollution patterns. Stronger wind s aloft capture the regional pollutant load, and can transport it for hundred s of kilo me ters down wind of the stagnated air mass’s center (NAR STO, 2000 at p. 3-34). For exampl e, air flow from west to east over the Appalachian M ountains can move air pollution originating within the O hio River Valle y into the OTR.
Studies undertaken by the NAR STO-NE field program also observed several regional scale me teorolog ical features arising from geographical features in the easternThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 12

U.S. that affect pollutant

transport. One import ant feature is the channeled flow of a nocturnal low level j et moving air pollution from the southwest to the northeast along the Northeast Corridor during overnight hours. The N ARSTO-NE field program observed nocturnal low level j ets on most nights preceding regional ozone episodes in the OTR, consistent with the observations of the NE-OP S ca mpaign.
Another importan t smal ler scale transport mechan ism is the coastal sea breeze that can s weep a shore pollutants originall y transported over the ocean parallel to the coastline. A n exa mple of this is the high ozone levels seen at ti mes along coastal Maine that move in from the Gulf of Maine after having been transported in pollution plumes from Bo ston, Ne w York Cit y, and other Northeast Corridor locations (NAR STO, 2000 at pp. 3-34 through 3-37).
As a result of the NA RSTO-NE field program, a conceptual picture of pollution transport into and within the OTR is pos sible. It consists of a combina tion of large-scale

s ynop tic flow from the Mid west interacting with various regional and smaller- scale transport and me teorologi cal features within the OTR, as illustrated in Figure 1-4

. S yn optic- scale transport from we st to east across the A ppalachi an Mountains occurs with the slow-moving stagnant high pressure s yst em s that foster large regional ozone episodes across eastern U. S. Regional- scale channeled flow s, specifical l y nocturnal low level j ets from the southwest to the northeast along the Atlantic Coa stal Plain, can occur within the

s ynop tic sy ste m. In addition, da yt i me sea breezes can significant l y affect ba y and coast line air pollution levels within the OTR (NAR STO, 2000 at 3-36 and 3-37, citing Blum entha l et

al. , 1997).
Figure 1

- 4 . Conceptual picture o f di ff erent transport regi mes contributing to ozone episode s in t he OTRThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 13

Lon g- range (sy

noptic scale) transport occurs fro m west to east across the App alachian Mountains

. Regional sc ale transport in channel ed flow s also occurs fro m west to e ast through gaps in the Appalachian Mountains and in nocturnal lo w level jets fro m southwest to northeast over th e Northeast Corridor. Da yt im e se a breezes can af fect local coastal areas by bringin g in air pollution originall y transported ne ar the surface a cross water parallel to the coast (e .g., along the M aine coastline)

. Figure fro m NARSTO , 2000 , citing Blumenthal et al.
, 1997

. 

### 1.6.5. New Englan d Air Q ualit y S tud y (NEAQS ) 2002-2004 The Ne w England Air Qualit y Stud y (NEAQ S) has to date conducted field

ca mpaigns during the summ ers of 2002 and 2004 to investigate air qualit y on the Eastern Seaboard and transport of N orth American emissions into the North Atlantic ( NEAQS, 2002). Transport of air pollution into the Gulf of Maine and s ubsequentl y into coastal

areas of northern New England received extensive attent ion. High ozone levels in northern N ew England occurwith light to moder ate wind s from s ource regions in the Northeast urban corridor, rather than under locall y stagnant conditions. The most

impor tant transport pathwa ys leading to high ozone in coastal New Hampshire and Maine are over water rather than over land. Transport over water is particul arl y i mportant

in this northern region of the OTR for several reasons. First, there is a per sistent pool of cooler w ater in the northern and eastern G ulf of M aine and Ba y of Fund y. This creates a smoother transport s urface for airpollutants relative to land transport, with a decrease in convective (vertica l) mix ing. Second, deposition of pollutants to the water

surface is ver y small compared to the more rapid deposition occurring on land. Third, the lack of convective m ixing allows pollution to be transported in different directions in la ye rs at different heights in the atmospher e (Angevine et al.
, 2004). During the summ er of 2002, researchers observed two transport events into coastal northern New England. The first occurring on July 22 through J ul y 23 involved large- scale sy

nopt ic transport in a 400-600 m la ye r over the G ulf of Maine that

was in contact with the water’s s urface. The s outhwesterl y flow brought ozone pollution up from the Ne w York Cit y, Bo ston and other northeastern urban locations into coastal northern New England. Ozone monitors on Maine’s coast extending from the New Hampshire border to Acadia National Park recorded elevated 1-hour average ozone levels between 88 and 120 ppb during this period. In a later episode during August 11-14, ozone and wind observations indicated the role of local- scale transport via a sea breeze (southeasterl y flow) bringing higher ozone levels into coastal Ne w Hampshire from a polluted lay er originall y transported off s hore in the G ulf of Maine in a s outhwesterl y flow arising out of the N ortheast urban corridor. Transport in an elevated la ye r also occurred with higher

ozone recorded at a moni tor on Cadillac M ountain in Acadia National Park relativ e to two monitors located at lower elevat ions in the park (Angevine
et al. , 2004).
The results of NEA QS indicate the importan t conditions contributing to ozone transport along the northern Ne w England coast. The cool waters of the G ulf of M aine allow for transport of air

pollutants over distances of 20-200 km in stable lay er s at the water’s surface with littl e pollutant deposition or dilution. Sea breezes can mod if y largescale s ynop tic transport over the ocean and bring high ozone levels into particular sitesThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 14

located on the coast. Transport within higher lay er s above the Gulf of Maine can carr y pollutants over much greater distances, 200-2000 km ( Angevine et al. , 2004).



### 1.6.6. Regional Atm ospheri c Measure me nt, Modeling, and P rediction Program ( RAMMPP ) 2003 The Regional Atmospheric Measurement, Modeling, and P rediction Program (RAM MPP) is a program led b y researchers at the Universit y of M ar yl an d. Its focus is developing a state- of-the-art scientific research tool to improv e understanding of air qualit y in the m id- Atlantic region of the U nited States. It has a numb er of facets, including ozone and PM 2 .5 pollutant level forecasting, aircraft, and surface measure me nts, real- ti me weather

forecasting, and che mic al transport model ing. During the Augu st 2003 electrica l blackout in the eastern United States, one of the largest in North Amer ican history
, scientists with RA MMPP w ere able to obtain airborne

me asurem ents that directl y recorded changes in air pollution due to the virtual shutdown of numerous coal-fired

power plants across a large part of this region (Marufu et al.
, 2004). Initial l y, aircraft measurem en ts were collect ed earl y in the day on Augu st 15, 2003 above we stern Mary la nd, which wa s outside the blackout region. These measure me nts

were co mpared with aircraft me asurem ents taken later that day over central Penns yl van ia, about 24 hours into the blackout. The comparison indicat ed a decrease in ozone concentrat ions of ~50 percent within the blackout region (as well as >90 percent decrease in S O 2 and ~ 70 percent reduction in light scatteredb y

particles). These reductions were also con sistent with comparisons to measurem en ts obtained over central Penn s yl van ia the previous ye ar during a period of simi lar s yn opti c patterns as occurred during the blackout. Forward trajectories indicated that the decrease in air pollution during the blackout benefited much of the eastern U nited States. The decrease in ozone was greater than expected

based on esti mat es of the relativ e contribution of po wer plant N O X em issions to ozone forma tion in the region. The researchers suggested that this could be due to underestim ation of power plant emissions, poor representation of po wer plant plum es in em ission models, or an incompl ete set of atmospher ic che mic al reactions in photoche mi cal models. This accidental “ real world” experi ment indicates that ozone forma tion acros s a large part of the eastern United States is s ensitive to po wer plant N O X em issions, and ma y be even more sen sitive to N O X reductions from these sources than currentl y predicted by air qualit y modeling.



### 1.7. Sum m a ry The chem istr y of ozone formation in the atmosphere involves reactions of NO X and V OC emissions from num erous s ources during periods of warm te mpera tures and abundant sun shine. The day

- to-da y pattern of ground-level ozone in the OTR varies according to a number

of meteoro logica l variables, such as sunlight, temper ature, wind speed, and wind direction. High levels of ozone within the OTR do not occurin isolation, indicat ing a broad regional air qualit y problem. Trends in 8-hour ozone levels since 1997 indicat e improve me nt in air qualit y, a reflect ion of numerous control strategies imp le me nted locall y, regionall y , and nationall y to reduce emissions of the pollutants that contribute to ozone formation.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 15

The scientific literature prior to 1985 contains a numb er of peer reviewed papers describing observed episodes of ozone and precursor pollutant transport. In 1991, a National Research Council report s um ma riz ed the state-of-the- science, which further highlighted the broad regional nature of the ozone problem in the eastern U.S. Since then, mul tipl e collaborat ive efforts and field camp aigns have further investigated specific aspects of the regional ozone problem affecting the OTR, and these provide a significant foundational basis for informed polic y decisions to i mprove air qualit y.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 16



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D ocument , Appendix K

– Sum mar

y of Ozone Transport A sses smen t Group recom me ndat ions to the U.S. Environmen tal Protection Agency as of June 20, 1997a

. Available at http://www.epa.gov/ ttn/n aaqs/ozone /rto/o tag/f inalrpt /chp1/ toc.ht m

. OTAG ( Ozone Transport As sessment Group). O TAG Technical Supporting

D ocument

. Chapter 2

– Regional and U rban Scale Modeling Workgroup. 1997b. Available at http://www.epa.gov/ ttn/n aaqs/ozone /rto/o tag/f inalrpt /chp2_new/ toc.ht m

. OTAG ( Ozone Transport As sessment Group). O TAG Technical Supporting

D ocument

. Chapter 4

– Air Qualit y Analy si s Workgroup. 1997c. A vailabl e at http://www.epa.gov/ ttn/n aaqs/ozone /rto/o tag/f inalrpt /chp4/ toc.ht m

. OTAG ( Ozone Transport As sessment Group). O TAG Technical Supporting

D ocument

. Chapter 1

– Overview. 1997d. Available at http://www.epa.gov/ ttn/n aaqs/ozone /rto/o tag/f inalrpt /

. Philbrick, C.R., W.F. R ya n, R. D. Clark, B. G. Doddridge, P . Hopke, and S .R. McDow. “A dvances in understanding urban air pollution from the N ARSTO-NEO PS program.” 83 rd Ameri can Meteorologic al Societ y 5 th Conference on Atmospheri c Chem istr y, Long Beach, CA, Feb. 8-12, 2003a.

Philbrick, C.S., W. R ya

n, R. Clark, P. Hopke, and S. Mc Dow. Processes controlling urban air pollution in the Northeast: Summer 2002. Final Report for the Penn s yl van ia Depart ment of Environmen tal Protection, July 25, 2003b. Available at http:// lidar1. ee.psu.edu/neopsW eb/publ icSite /neopsdep/Fin al%20Rep- Part%201-7.pdf

.
Sill man, S ., J.A. Logan, and S .C. Wofs y. “The sensitivit y of ozone to nitrogen oxides and h yd rocarbons in regional ozone episodes.” J. Geophys. Res. 95 , 1837-1851, 1990.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 18

Stoeckenius, T. and Kemball- Cook, S. “ Determ ination of representativen ess of 2002

ozone season for ozone transport region SIP model ing.” Final Report prepared for the Ozone Transport Com mission, 2005.

Trainer, M., E.J. Willia ms, D. D. Parrish, M.P. Buhr, E.J. Allwine, H.H. Westberg, F.C. Fehsenfeld, and S.C. Liu. “M odels and observations of the impa ct of natural h yd rocarbons on rural ozone.” Nature 329 , 705-707, 1987.

Trainer, M., D. D. Parrish, M.P. Buhr, R.B. Norton, F.C. Feh senfeld, K. G. Anlauf, J .W. Bottenhei m, Y.Z. Tang, H .A. Wiebe, J. M. Roberts, R.L. Tanner, L. Newman, V.C. Bowersox, J. F. Meagher, K .J. Olszy na , M.O. Rodger s, T. Wang, H. Berresheim
, K.L. Demerjian, and U. K. Ro yc howdhur y

. “C orrelation of ozone with N O y in photoche mi call y aged air.” J. G eophys. Res. 98 , 2917-2925, 1993.

USEP A. Ozone and your Health , EPA-452/F-99-003, Septe mber 1999 (availab le at http://www.airnow.gov/ind ex.cfm? act ion=static.bro chure ).

USEP A. Technical

Support Document

for the Final

Clean Air Interstate Rule: Air Quality Modeling . USEP A OA QPS, March 2005. Available at http://www.epa.gov/ clean airin terstat erule /pdfs/fina ltech02.pdf

.
USEP A. Air

Q uality C

riteria for Oz one and Related Photochemical

Oxidants: Volume 1

. USEP A, EPA-600/R- 05/004aF, February 2006.

White, W.H., D.E. Patterson, and W.E. Wilson, Jr. “U rban exports to the nonurban troposphere: Results from P roject M ISTT.” J. Geophys. Res. 88 , 10,745-10,752, 1983.

Wolff, G.T., and P.J. Lioy

. “D evelop ment of an ozone river associated with sy nopti c scale episodes in the eastern United States.” Envtl. Sci. & Technol. 14, 1257-1260, 1980.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



## 2. METEOROLOGY AN D EV O LUTION OF O Z ONE EPISODES IN THE O ZONE T RA NSPOR T REGION
The following s ections describe current kno wledge of the factors contributing to

ozone episodes in the OTR. The general de scription of weather patterns com es main l y from the work of Ry an and Dickerson (2000) done for the Mar yl and Departmen t of the Environ ment. Further inform ation is drawn from work by H udson (2005) done for the Ozone Transport Com mission and from a mid- Atlantic regional air qualit y guide b y MAR AMA (2005). The regional nature of the ob served ozone episodes in the OTR is reinforced in modeling studies b y the U SEPA for the Clean Air Interstate Rule.



### 2.1. Large- scale wea ther pat terns
R ya n and Dickerson (2000) have described the general met eorologic al features conducive to ozone forma tion and transport that are pertinent

to the OTR. On the local scale, met eorologi cal factors on which ozone concentrations depend are the amoun t of availab le sunlight (ultraviole t range), temper ature, and the a mount of space (volume) in which precursor emissions mix. S unlight drives the ke y photoche mi cal reactions for

ozone and its ke y precursor s and the em issions rates of man y precursor s (isoprene for

exa mple) are te mperatur e dependent. Em issions confined within a smal ler volume result in higher concentrat ions of ozone. Winds in the lowe st 2 km of the atmosphere cause horizontal mixing w hile vertica l te mperatur e and mo isture profiles drive vertica l mix ing. High ozone is ty

pi ca ll y as sociated with weather conditions of few clouds, strong te mpera ture inversions, and light wind s. The large- scale weather

pattern that comb ines me teorologi cal factors conducive to high ozone is the presence of a region of upper air high pres sure (an upper air ridge) with its central axis located west of the OTR. The OTR east of the axis of the highpressure ridge is characteriz ed b y sub siding (down ward moving) air. This reduces upward mot ion necessar y for cloud forma tion, increases temp eratur e, and supports a stronger lower level inversion. While the upper air ridge is located

west of the OTR, surface high pressure is ty pi ca ll y quite diffuse across the region. This pattern occurs throughout the ye ar but is most comm on and longer lived in the summ er months (R ya n and Dickerson, 2000).
The large, or sy

nopt ic, scale, weather

pattern sketched above has impor tant imp lic ations for transport into and within the OTR. First, the persistence of an upper air ridge we st of the OTR drives generall y west to northwest wind s that can carry ozone generated outside the OTR into the OTR. A key point from this wind-driven transport mode is that stagnant air is not alway s a factor for high ozone episodes in the OTR. Second, the region in the vicinit y of the ridge axis, being generall y cloud free, will experience significant

radiation al cooling after

sunset and therefore a strong nocturnal inversion will form. This inversion, ty pi ca ll y only a few hundred me ters deep, prevents

ozone and its precursors from mixing do wnward overnight. Above the inversion la ye r, there is no opportunit y for destruction of the pollutants b y surface depo sition, thus increasing the pollutants’ lifeti me s aloft and consequentl y their transport distances. Third, with diffuse surface high pres sure, sma ller scale effects can become dominant in theThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2

lowest lay er s of the atmosphere. These include ba y and land breezes, the A ppalachi an lee side trough, and the developm ent of the nocturnal low level jet. Nocturnal low-level jets

are comm on l y observed during high ozone events in the OTR (Ry an and Dickerson, 2000). As previously men tioned in Section 1, Stoeckenius and Kembal l- Cook (2005) have identified five ozone patterns in the OTR as a guide to an historical ozone episode’s representativ eness for air qualit y planning purpo ses. The y also described the

me teorolog ical conditions that are generall y as sociated with each of these patterns. Appendix B presents the five t yp es with the additiona l me teorologi cal detail.



### 2.2. Meteorological m ixing processes An import ant elemen t in the production of severe ozone events is the abilit y of the at mosphere through temper ature inversions to inhibit the mix ing processes that under

norma l conditions would lead to dilution of the em itt ed pollutants. For the purpo ses of this discus sion, w e focus on two major classes of te mpera ture inversions, (1) nocturnal (radiativ e) and (2) subsidence. Figure 2-5 s hows an examp le of nocturnal and sub sidence inversions in a te mpera ture profile taken over Alban y, N Y, on Septemb er 1, 2006 at 7 a.m. eastern standard tim e. The figure show s two distinct te mpera ture inversions

– the ground-based nocturnal inversion and an inversion at about 1600 me ters caused by the sinking mo tion (subsidence) of the at mosphere in a high pressure s yst em

. Figure 2

- 5 . Tem perature prof ile taken over Alban y, N Y, on Septe mb er 1, 2006 at 7 a.m . eastern standard ti me



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8 50 mThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3



### 2.2.1. Nocturnal inversions Land surfaces are far more efficien t at radiating heat than the at mosphere above, hence at night, the Earth’s surface cools more rapidl y than the air. That te mpera ture drop is then convey ed to the lowe st hundred met ers of the at mosphere. The air above this lay er cools more slowly
, and a temper ature inversion forms. The inversion divides the at mosphere into two la ye rs that do not mix. Below the nocturnal surface inversion, the surface wind s are weak and an y pollutants emi tted overnight accumul ate. A bove the inversion, winds continue through the night and can even become stronger as the inversion isolates the winds from the friction of the rough s urface.
In the morning, the sun warms the Earth’s surface, and conduction and convection transfer heat up ward to warm the air near the surface. By about 10:00 – 11:00 a.m., the te mpera ture of the surface has risen sufficientl y to remov e the inversion. Air from above and below the inversion can then mix freel y. D epending on whether the air above the inversion is cleaner

or more polluted

than the air

at the surface, this mixing can either lower or increase air pollution levels.



### 2.2.2. Subsidence inversions
Severe ozone events are usuall y as sociated with high pre ssure s ys tem s. In the upper atmosphere, the winds around a high pres sure sys tem move in a clockwise direction. At the ground, friction between the ground and the wind s turns the winds away from the center

of the sy ste m and “divergence” occurs, me aning that air at the surface

moves a wa y from the center. With the move me nt of air horizontal l y awa y from the center of the high at the surface, air aloft moves verticall y do wnward (or “s ubsides”) to replace the air that

left. Thus, the divergence awa y from the high pres sure s ys tem gives rise to subsidence of the at mosphere above the high. The subsiding mo tion causes the air to

warm a s it moves downward and is compr essed. A s the w arm er air meets the colder

air below, it forms an inversion. A s ubsidence inversion is particularl y strong because it is associated with this large scale do wnward mot ion of the atmosphere. The subsidence inversion caps pollution at a higher altitude in the atmosphere (ty pi ca ll y from 1200 to 2000 me ters), and it is far more difficult to break down than the nocturnal inversion. Hence the subsidence inversion li mits vertical m ixing in the midd le of the da y during an air pollution episode, keeping pollutants trapped closer to the ground.



### 2.3. Meteorological transport processe s
2.3.1. Introduction Figure 2-6 s hows the classic s ynop tic weather pattern at the Earth’s surface associated with severe ozone episodes within the OTR. A quasi-stationar y high pressure

s yst em (the Bermuda high) extends from the Atlantic Ocean we stward into interior southeastern U. S., where a second weaker high is located. Surface wind s, circula ting clockwise around the high, are especiall y light in the vicinit y of the secondar y high. Farther north, a southwesterl y flow strengthens toward Ne w York and southern New England. This situation illustrates two circula tion regi mes often existing in OTR ozone episodes: more stagnant conditions in southern areas and a moderat e transport flow in the OTR from s outhwest to northeast. In addition, as discus sed previously
, high pres sureThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

s yst em s exhibit

subsidence, which results in temper ature inversions aloft, and cloud free skies.
Closer to the surface, the Appalachian M ountains induce changes in the wind field that also pla y import ant roles in the formation and transport of ozone in the OTR. The mounta ins act as a phy si cal barrier confining, to s ome degree, pollution to the coastal plain. The y also induce local effects s uch as mountain and valle y breezes, which, in the

case of do wn-slope wind s, can raise surface temper atures thereb y increasing che mica l reactiv it y. In addition, mountains create a lee side trough, w hich helps to channel a more concentrat ed ozone plume, and contribute to the forma tion of nocturnal low level j ets, the engine of rapid nighttim e transport. The Atlantic Ocean also pla ys a strong role during ozone episodes where sea breezes can draw either heavil y ozone-laden or clean mar ine air into coastal areas. Figure 2

- 6 . Schem atic o f a t ypical w e at her p attern a ssociated w it h severe ozone episode s in t he OTR

Meteorologica l processes that transport ozone and its precursor s into and within the OTR can roughl y be broken down into three levels: ground, mid and upper. The following sections discuss the three wind levels associated with meteoro logica l transport processes in more detail.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5



### 2.3.2. Ground level wi nds
Land, sea, mountain, a nd valley breezes In the OTR, land and sea breezes, and mounta in and valle y breezes can have an impor tant influence on local air qualit y

. These local winds are driven by a difference in te mpera ture that produces a difference in pressure. Figure 2-7 s hows a schema tic of the forma tion of a sea breeze. The s ea breeze forms in the afternoon when the land is considerabl y hotter

than the ocean or ba y. Air then flows from the high pressure over the

ocean toward the low pres sure over land. At night, the oppo site ma y happen as the land cools to below the ocean’s te mperatur e, and a land breeze blows out to s ea. Because the nightti me land and water

tempera ture differences are usuall y much smal ler than in the da y, the land

breeze is weaker than the sea breeze. Sea breezes t yp ic al l y onl y penetrate a few kilo met ers inland because the y are driven by temp erature contrasts thatdisappear inland.
Figure 2

- 7 . Illustration of a sea bree ze and a land breeze

a) Sea Breeze b) La nd Breeze Figure from Lutgens & Tarbuck
, 2001.
Along coastlines, such as coastal New England, sea breezes bring in air pollution transported nearthe surface over water from urban locations located to the southwest. Figure 2-8 s hows the average 2000-2002 wind direction frequenc y for elevated 1-hour

ozone in the vicinit y of the Kennebec and Penob scot Rivers in Maine. There is a clear

max im um of pollution in the direction of the sea breeze. These sites are located man y mi les upriver

from the coast, and receive ozone transported over waterfrom the sea up through the coastal ba ys and rivers.
In other cases, sea breezes can affect air qualit y in coastal cities because, under stagnant s ynop tic- scale winds, a cit y ’s emissions ma y be recircula ted or pushed back

over land after

having drifted out

over the sea earlier. Before sea breeze circulation begins, air pollution from a coastal cit y can move out over the water. In the absence of a shift in winds due to a sea breeze, the cit y ’s air pollution will be blown away

. When a s ea breeze circula tion sets up, however, the polluted air is pushed back toward the cit y

. The sea breeze onl y pu shes a few miles inland, which is w here the barrier to mixing lies. Later in the da y, the air

ma y be quite clean on the ocean side of the cit y, but the air isThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6

usuall y quite dirty on the inland side. The cit y s uffers from its own recirculated pollution, and also from the sea breeze that does not allow pollution from the cit y to flow awa y from it. Appendix E presents more detailed infor mation on sea breezes and flow over the

ocean that contribute to ozone transport in parts of the OTR.
Figure 2

- 8 . A verage 2000 – 2002 wi nd direction f requenc y as sociated w it h elevated one-hour ozone levels in coastal Maine

The bay breeze is a shallow circulation over large inland bay s, and ma y onl y extend a couple hundred m eters above the surface. For example, bay breezes from the Chesapeake Ba y

often make Baltim ore’s sum mer ti me air qualit y particular l y poor. Air from the cit y cannot escape directl y across the Bay

. O n the other hand, a few mi les closer to the Ba y, conditions are often considerabl y cleaner, since no fresh em issions have gotten into the air

there since earlier that morning. Polluted air from the we st side of the Ba y can still mix up ward, w here it m eets the stronger winds aloft, pas s over the Ba y breeze circula tion and come back down on the east side of the Bay

. Mountain and valle y breezes are also driven b y a tempera ture contrast. In the da yt i me , the side of the mount ain will heat up more quickly than the valle y, and hence a flow from the valle y to the mount ain re sults. At night this flow is reversed as the mount ain side cools more quickl y than the valle y. A s a result of these differences in cooling and heating, during the day
, warm winds blow up toward the peaks from the valle y below, w hile at night, cool air sink s and flow s down the valle y, settling in the lowest points. Local topograph y is very import ant in generating this phenomenon, mak ing the breeze unique to a particular area.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 7

Mountains and valle ys also serve to isolate air in the valle y s, while air at the mount aintops ma y be com ing from very far awa y. Mountain winds, inversions, and mix ing are quite complex. On a quiet night, the mounta intop ma y be in the free troposphere, open to long- range transport, w hile the valle y below is usuall y capped by a nocturnal inversion, isolating pollution in the valle y. Air qualit y measure me nts taken during plane flights in the Shenandoah River Valle y have shown that the air pollutants in the valle y ma y be rather

different from the air atthe nearby peaks. Cities on the we stern side of the mount ains will find that the A ppalachians are capable of dam mi ng pollution up against the m (M ARAM A, 2005 at pp. 42-43). 

### Appalachian lee side trough The Appalachian lee side trough forms on the leeward (down wind) side of the Appalachian M ountains. In a sense, it is the da yt im e companion to the nocturnal low level jet, discussed below, because it forms under simi lar stagnant conditions; however, the mechan ism for its formation is different. In the OTR, a lee side trough forms when winds blow over the A ppalachi an Mountains and do wn the lee side of the mountain range to the coastal plain. As the colu mn descends down the lee side, it stretches verticall y and spins faster, pulling up air and creating low pres sure, thus rotating the winds to the southwest. Because the air is t yp ic all y rather

dry
, and the trough itself is rather weak, it does not u suall y lead to showers and thunderstorms the way a trough associated with other weather sys te ms w ould. It does cause winds to shift their direction, so a wind that

com es over the mountains from the west will turn and blow from the s outhwest along the coastal plain. Therefore, when surface wind s on the coastal plain are from the southwest, if the Appalachian lee side trough is in place, it ma y be that the air actuall y came from the we st, descended, and turned. The impl ica tion for airqualit y polic y is straightforward. Pollution mak ing its way over the moun tains from the west will turn once it reaches the coastal plain and come from the southwest. Because surface winds are then from the southwest, when the A ppalachi an lee side trough is in place, the li mi ts of a nonattain me nt area’s airshed will be expanded farther s outh and west than the y migh t otherwise be (MAR AMA, 2005 at pp. 41-42). Studies have observed high ozone levels in the OTR associated with a lee side trough east of the Appalachian M ountains and aligned with the Northeast Corridor (Gaza, 1998; Kleinm an et al. , 2004).



### 2.3.3. Mid-level w inds: Noct urnal low level jets The nocturnal low level c jet is a locali zed region of rapid wind s in the lower at mosphere (t yp ic al l y 500-1500 m above the ground level) that form at night under the

same calm conditions often present in a pollution episode. Forming j ust above the nightti me te mperatur e inversion ment ioned previousl y, the nocturnal low level j et depends on the isolation from the surface provided b y the inversion. It is primari l y a nocturnal pheno menon that occurs more frequentl y during the spring and summ er
seasons. A nocturnal low level jet is generall y found w here a range of mountains m eets a flat plain. There is a particular l y strong nocturnal low level j et in the Great Plains of the

c “ Lo w level” in this ins tance i s relative to upper level jets occurring in the upper troposphere to l ower stratosphere at heights of 10-15 km above the ground level. It i s not a “ground

level” phenomenon of the t yp es described i n the previous section.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 8

central U nited States on the eastern side of the Rock y Mountains. O n the Eastern Seaboard, nocturnal low level jets develop along the Atlantic Coastal Plain located to the east of the Appalachian M ountains and to the west of the Atlantic Ocean. While the t yp ic al wind s peed mini mu m of a nocturnal low level jet is often defined a s mor e than 12 me ters per second (m s -1 ), R ya n (2004) ha s proposed a weaker min im um s peed criterion of 8 m s - 1 in the East because of the expected weaker terrain- induced forcing in this region. The mid- Atlantic nocturnal low level jet has a width of 300-400 km (to its half peak value) and a length scale of more than 1500 km, following closely the orientat ion of the A ppalachi an Mountains.
The nocturnal low level jet forms when fronts and storm sys te ms are far awa y. Surface wind s are parallel to the terrain, w hich in the case of the OTR is southwest running over the Atlantic Coastal Plain in front of the A ppalachi an Mountains. The nocturnal low level j et forms because land cools quicker than the air

above it at night. The quickl y cooling land results in the air closest to the surface cooling quicker than the air higher above. This creates a tempera ture inversion that separates the at mosphere into la ye rs. The warmer

air above the inversion la ye r (~200-800 m above ground) loses the frictiona l effect of the s urface and increases in speed. In the eastern United States, the nocturnal low level j et ha s been observed in Georgia, the Carolinas and Virginia (Weis man, 1990; S

jo stedt et al. , 1990) in addition to the OTR ( NARSTO, 2000). Appendix F de scribes a specific exa mple of an observed nocturnal low level jet occurring

over the length of the OTR during a period of high ozone in July 2002. Upper air studies have ob served ozone being transported overnight in nocturnal low level jets in the OTR (Woodman et al. , 2006). The Mar yl and Departmen t of the Environ ment (M DE) operates an upper air profiler at the Howard Universit y ( HU) site located in Beltsville, Mary la nd. On Augu st 5, 2005, two helium- filled balloons carry in g
ozone sen sors (called “ozonesondes”) were launched at the HU – Beltsville site in the earl y morning hour s. Using the upper air profiler, a nocturnal low level jet of 15 m s -1 was observed between approxima tel y midnigh t and 7:30 a.m. One ozonesonde wa s launched at 3:30 a.m. and measured an ozone concentration of approxima tel y 95 ppb at about 600 met ers, w hich is within the nocturnal low level j et. Another ozonesonde was launched at 7:30 a.m. and measured an ozone concentration of approxima tel y 90 ppb at about 1,000 meters ( Figure 2-9 ). Each of the ozone concentrat ions wa s observed at approxi mat el y the same height as the nocturnal temp eratur e inversion as indicated b y the kink in the tempera ture profile. The observations indicated that elevated ozone concentrat ions are within the nocturnal low level jet.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 9

Figure 2

- 9 . Ozonesonde me as urem en ts on A ugust 5, 2005 o f elevated ozone concentrations in a n octurnal lo w level jet above Beltsville, MD



### 2.3.4. Upper level w in ds: Ozone and precursors a loft Theoreti cal and numeri cal model simulat ions have suggested for some time that there is a strong regional component to urban air

qualit y in the northeastern United States (Liu et al ., 1987; Sill man et al ., 1990; Mc Keen et al ., 1990). Since 1992, over 300 aircraft flights have been mad e to measure vertica l profiles of ozone, the nitrogen oxides, carbon dioxide, s ulfur dioxide, and more recentl y aerosol particl es during high ozone episodes. d Figure 2-10 s hows the results of profiles taken over central Virginia on J ul y 15, 1995, at about 9:00 am on the last day of a four da y severe ozone episode. D uring this episode, wind s m easured at Sterling, Virginia (I AD) in the 500-3000 m la ye r, where

ozone wa s at a max im um , were consistentl y from the west to the north. This w as particul arl y true on July 15. There were no periods of stagnation or reversal of wind direction during this period. Figure 2-10 s hows that the ozone mixing ratio above the boundar y lay er is much larger than that at the ground, peaking at about 1200 m eters.
An exam inat ion of the various pollutant data in Figure 2-10 helps to identif y possible s ources of the elevated ozone. It should be noted that while both auto mobiles and po wer plants emi t NO X , automob iles em it carbon monoxide (CO) but not sulfur dioxide (SO 2 ), w hile power plants emi t SO 2 but not CO. The C O profile is not correlated well with the ozone data, indicating that the source of the ozone is not from local s ources, i.e., automob iles. The peak in the NO Y e profile at around 800 meters is an indication of “aged air” (hence transport) as a number of studies have found a strong relationship between increasing ozone and N O Y in photochem ical l y aged air masses (Trainer et al.
, 1993; Kleinman et al. , 1994; Olszy na et al. , 1994). Finall y , the peak in the SO 2 profile,

d These measurements were made as part of the University of Mar yl and ’s RAMM PP (Regional Atmospheric Measurement, Modeling, and Prediction Progr am) under the sponsorship of ARMA, MARAMA (Mid-Atlantic Regional Air Mana gement Association), VADEQ (Virginia Department of Environmental Quali t y)
, and NCDEQ (North Carolina Department of Environmental Qualit y)

. e NO Y = NO + NO 2 + all other o xi dized ni trog en products of NO X , excluding N 2 O. 

# 7: 30 AM A M 3: 30 A M A MThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 10

which occurs above the nocturnal inversion, is unlikel y to come from local sources. Indeed the presence of the S O 2 leads to the conclusion that the air is coming from power plants we st of the Appalachian M ountains.
Figure 2

- 10 . Altitude pro files for ozone, carbon m on oxide, NO Y , and SO 2 taken o n July 15, 1995

During the same Jul y

1995 period, measure me nts aloft in other parts of the OTR also recorded high ozone overnight in la ye rs 500 m or higher above the s urface. Ozone aloft concentrat ions above Poughkeepsie, N Y and New Haven, CT approached levels of 120 ppb or greater

on the night of J ul y 14 (Zhang & Rao, 1999). Figure 2-11 displa ys the aircraft measure me nts above P oughkeepsie, NY around 4 a.m. EST.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 11

Figure 2

- 11 . Observed vertical ozone profile me as ured above Poughkeepsie, NY at abo ut 4 a.m . EST on Jul y 14, 1995

0 20 4 0 60 80 100 12 0 140



### Oz o n e (p p b ) 160 0

120 0

800

400Altitude (meters) 8

- ho ur st and ard

Ob serv e d ozo ne

0 20 4 0 60 80 100 12 0 140



### Oz o n e (p p b ) 160 0

120 0

800

400Altitude (meters) 8

- ho ur st and ard

Ob serv e d ozo ne

Note: The fi gure in cludes a vertical lin e at 85 ppb for comparing aloft measurements with the 8- hour ozone NAAQS (observed ozone data from Zhan g & Rao, 1999).

The aircraft

me asurem ents since 1992 reinforce the previously men tioned observations by Clarke and Ching (1983) during the summ er of 1979, in which aircraft

me asurem ents recorded aloft ozone concentrations of about 90 ppb transported overnight from eastern Ohio and entering into the Northeast Corridor over a region stretching from the lower Hud son River Valle y north of New Y ork Cit y down across eastern Pennsy lv ani a and into Mary la nd j ust we st of Baltim ore. The me asurem ents also ob served NO X aloft during the overnight hour s that could contribute to additional ozone format ion in the OTR as it mixed do wn to the surface in the morning.
The presence of high levels of ozone and precursors aloft across a large spatial region gives rise to the concept of an “ ozone reservoir” existing at night ju st above the nocturnal inversion boundar y. The pollutants in this reservoir are not sub ject to destruction at the s urface, and can be transported long distances in the wind flows created b y the sy nopt ic scale weather

patterns conducive to ozone formation and transport.



### 2.4. Atm osphe ric m odeling of regional ozone transport Modeling results b y

the U SEPA for the Clean Air Interstate Rule (CAIR) further underscore the regional nature of ozone transport into and within the OTR through theThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 12

various pathway s described in the above sections. Based on ozone air qualit y model ing results, the USEP A tabulat ed the percent contribution to 8-hour ozone nonattain me nt in a number of OTR counties. The USEP A mod eled the contributions for the base y ea r 2010, which included

imple me nt ation of the NO X SI P Call and other existing and promulg ated control programs. Table 2-1 show s the CAIR re sults for the OTR counties (USEP A, 2005, from Table V I-2).

Table 2

- 1 . USEPA C AI R mo deling results o f percent contribution to 8-hour ozone nonattain me nt in OTR counties in 2010 due to tran sport fro m u p wi nd s tates

2010 Base Nonattainment Cou nties 2010 Base

8-Ho ur Ozone (pp b) Pe rc ent o f 8- H our Ozone d ue to Tra nsport Fairfield CT 92 80 % M iddlesex CT 90 93 % New Haven CT 91 95 % Wash ington DC 85 38 % Newcastle DE 85 37 % Anne Arundel MD 88 45 % Cecil MD 89 35 % Harford MD 93 31 % Kent MD 86 47 % Berg en N J 86 38 % Camden NJ 91 57 % Gloucester

NJ 91 62 % Hunterdon N J 89 26 % MercerN J 95 36 % M iddlesex N J 92 62 % Mon mouth NJ 86 65 % Morris NJ 86 63 % Ocean NJ 100 82 % Erie NY 87 37 % R ichmond NY 87 55 % S uffolk NY 91 52 % Wes tchester NY 85 56 % Bucks PA 94 35 % C hester PA 85 39 % Mon tgomery PA 88 47 % P hiladelphia P A 90 55 % Kent R I 86 88 % Arlington VA 86 39 % Fairfax VA 85 33 % From USE PA, 2005 (Table VI

- 2) The CAIR modeling by the USEPA also provides informa tion on the upwind

areas (by state) contributing to downwind nonattain me nt in the OTR counties. Table 2-2 presents the upwind states significantl y contributing to 8-hour ozone nonattainm en t in counties within the OTR, according to significance criteri a used b y the U SEPA (U SEPA, 2005, from Table V I-5). The states listed in the table a s significant l y contributing toThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 13

downwind ozone nonattain me nt in the OTR counties include states outside of the OTR, indicat ing the broad regional scale of the ozone transport problem.

Table 2

- 2 . U SEPA CA IR m od eling results of up w in d states that m ak e a sig nificant contribution to 8-ho ur ozone in do w n wi nd OTR n onattainm en t counties
Do wn wi nd State/County Upw in d States CT Middlese x MA N J NY OH PA VA CT New Haven MD/DC N J NY OH PA VA W V CT Fairfield MD/DC N J NY OH PA VA W V Dis trict of Co lumbia MD/DC OH PA VA DE New Castle MD/DC M I NC OH PA VA W V MD Harford NC OH PA VA W V MD Kent M I NC OH PA VA W V MD Cecil M I OH PA VA W V MD Anne Arundel M I NC OH PA VA W V N J Ocean DE MD/DC M I NY OH PA VA W V N J Ber ge n MD/DC M I OH PA VA W V N J Gloucester DE MD/DC M I OH PA VA W V N J Morris DE MD/DC M I NY OH PA VA W V N J Middlese x DE MD/DC M I NY OH PA VA W V N J Hunterdon DE MD/DC OH PA VA W V N J Camden DE MD/DC M I OH PA VA W V N J Merce r DE MD/DC M I NY OH PA VA W V N J Monmouth DE MD/DC M I NY OH PA VA W V NY Erie MD/DC M I N J PA VA WI NY Westchester MD/DC N J OH PA VA W V NY Richmond MD/DC M I N J PA VA W V NY Suffolk CT DE MD/DC MI NC NJ OH PA VA W V PA Montgomer y DE MD/DC N J OH W V PA Phi ladelphia DE MD/DC M I NJ OH VA W V PA Chester DE MD/DC M I NJ OH VA W V PA Bucks DE MD/DC M I NJ OH VA W V RI Kent CT MA N J NY OH PA VA VA Arlington MD/DC OH PA VA Fairf

ax MD/DC OH PA W V From USE PA, 2005 (Table VI

- 5). S tates are l isted alphabetically and not according to order of influence. While the USEP A mode led 40 eastern U.S. counties as in nonattainm en t of the 8- hour ozone N AA QS in the 2010 base y ea r (including counties not in the OTR), it projected that only three of those 40 counties would come into attain me nt by 2010 with the additional N O X reductions of CAIR ( USEPA, 2005, p. 58). The U SEPA modeling does predict that ozone will be lower in the rema ining nonattain me nt counties by 2010 due to CAIR, with additional counties coming into attain me nt by 2015. The CAIR reductions, therefore, will bring the OTR nonattainm en t counties closer to attainm en t b y 2010, but will not result in attainm ent for a large majorit y of OTR counties predicted to be in nonattainm en t in 2010 prior to imp le me nta tion of CAIR.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 14



### 2.5. Sum m a ry This section has sum mar ized current kno wledge of the meteoro logic al processes that affect local ozone levels within the OTR. A conceptual description of transport within the OTR can be divided into three principle compon ents: ground level transport at the surface, transport by the nocturnal low level jet, and transport aloft. All three modes of transport depend on the location of the high pressure s yst em

. Ground level transport is the result of interac tion between the sy nopt ic flow and local effects, s uch a s the sea breeze and the Appalachian lee side trough. Transport within the OTR can occur by the nocturnal low level j et that forms late at night or in the very earl y morning hour s. This phenom enon is a result of the differential heating of the air between the Appalachian Mountains and the Atlantic Ocean. It has been observed throughout the Eastern Seaboard from Georgia to Maine. The nocturnal low level j et can transport ozone that formed within the OTR or w as transported into the OTR from outside the region. Transport aloft is domin ated by the anti- c yc lo nic flow around a high pre ssure s ys tem , w hich can lead to transport of an ozone reservoir into the OTR created by emissions in areas that lie outside the OTR. Local emissions within the OTR add to the polluted air mixing do wn from above that arrived from more distant locations. Atmospheri c mode ling b y the U SEPA underscores the ob servations that the OTR’s ozone proble m has contributions from outside and up wind of the region. Pollution sources in the Ohio River Valley and the Southeast significantl y contribute to ozone nonattain me nt problems in various portions of the OTR.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 15



### References

Clarke, J.F., and J .K.S. Ching. “A ircraft observations of regional transport of ozone in the northeastern United States.” Atmos. Envt. 17 , 1703-1712, 1983.

Gaza, R. S. “Me soscale met eorolog y and high ozone in the northeast United States.” J. Applied Meteor. 37 , 961-977, 1998.

Hudson, R. “ A Conceptual Model for Ozone Transport.” Universit y of Mary la nd, Dept. of Atmospheri c and Oceanic Science. Prepared for the O zone Transport Com mission. Draft N ov. 29, 2005.

Klein man, L., Y .N. Lee, S. S pringston, L. Nunnermack er, X. Zhou, R. Brown, K

. Hallock, P. Klotz, D. Leah y, J. Lee, and L. Newman. “O zone F orma tion at a Rural Site in the Southeastern U nited States.” J. G eophys. Res

. 99 , 3469-3482, 1994.

Klein man, L., W.F. Ry an , P. H. Daum, S .R. Springston, Y .-N. Lee, L.J. N unnerm acker, and J . Weinstein- Lloy d. “A n ozone episode in the Philadelphia metropo lit an area.” J. Geophys. Res. 109 , D20302, doi:10.1029/2004JD004563, 2004.

Liu, S. C., M . Trainer, F . C. Fehsenfeld, D . D. Parrish, E. J. Willia ms, D. W. Fahey
, G. Hubler, and P. C. M urph y. “O zone production in the rural troposphere and the imp lic ations for regional and global ozone distributions.” J

. Geophys

. Res

. 92 , 4191– 4207, 1987.

Lutgens, F., and E. Tarbuck. The Atmosphere: An Introduction to Meteorology , 8 th ed., 512 pp., Prentice Hall, Upper Saddle River, New Jer se y, 2001.

MAR AMA ( Mid- Atlantic Regional Air Manage ment A ssociation). A guide to midAtlanti c regional

air quality. MAR

AMA. Baltim ore, MD, pp. 2-3, 2005 (available online at w ww.mara ma .org/repor ts ).

McKeen, S. A., M . Trainer, E. Y. H sie, R. K . Talla mr aju, and S. C. Liu. “O n the indirect deter min ation of atmospheri c OH radical concentrations from reactive hy droc arbon

me asurem ents.” J

. Geophys

. Res

. 95 , 7493–7500, 1990

.
NAR STO. An As sessment of Troposphe ric Oz one Pollution . NAR STO, Jul y 2000.
Olszy na , K.J., E.M. Baile y, R. Simonai tis and J .F. Meagher. “O 3 and N O y Relationships at a Rural Site.” J. Geophys. Res

. 99 , 14,557-14,563, 1994.

R ya n, W.F. and R.R. Dickerson. “ Regional transport of pollutants and i mpli cations for 8- hour ozone non-attainm en t areas in Mary la nd.” Report prepared for the Mary la nd Depart ment of the Environ ment, Final ver sion 2.2, 2000.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 16

R ya n, W.F. “ The low level j et in Mary la nd: P rofiler observations and preli minar y cli ma tolog y. ” Report prepared for the Mary la nd Departm ent of the Environ ment, Air and Radiation A dm inistra tion, 2004.

Sill man, S ., J. A. Logan, and S . C. Wofs y. “A regional scale model for ozone in the United States with s ubgrid representation of urban and power plant plumes.” J

. Geophys

. Res

. 95 , 5731–5748, 1990.
Sj ostedt, D.W., J.T. Sigmon, and S .J. Colucci. “The Carolina nocturnal low-level jet: S yn optic clim ato log y and a case stud y. ” W eath er and Forecasting

. 5 , 404-415, 1990.

Stoeckenius, T. and Kemball- Cook, S. “ Determ ination of representativen ess of 2002

ozone season for ozone transport region SIP model ing.” Final Report prepared for the Ozone Transport Com mission, 2005.

Trainer, M., D. D. Parrish, M.P. Buhr, R.B. Norton, F.C. Feh senfeld, K. G. Anlauf, J .W. Bottenhei m, Y.Z. Tang, H .A. Wiebe, J. M. Roberts, R.L. Tanner, L. Newman, V.C. Bowersox, J. F. Meagher, K .J. Olszy na , M.O. Rodger s, T. Wang, H. Berresheim
, K.L. Demerjian, and U. K. Ro yc howdhur y

. “C orrelation of Ozone with NO y in Photoche mic all y A ged Air.” J. Geophys. Res

. 98 , 2917-2925, 1993.

Weis man, R.A. “A n observational stud y of warm sea son southern A ppalachi an lee troughs. Part I: Boundary la ye r circulat ion.” Monthly W eath er Review

. 118 , 950-962, 1990.

Woodm an, M.F., D .T. N gu ye n, D.J. K rask, E. J oseph, V. Davis, R. Hoff, R. Roger s, M.G. Sey bold. “ Mar yl and Ozonesonde Campaign 2005.” Poster at EPA N ational Air Qualit y Conference, San Antonio, TX, 2006.
Zhang J. and S.T. Rao. “The role of vertical mix ing in the te mporal evolution of groundlevel ozone concentrations.” J. Applied Meteor. 38 , 1674-1691, 1999.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



## 3. O Z ONE-FORMING POLLUT ANT E MISSI ONS
The pollutants that affect ozone formation are volatil e organic compounds (VOC s) and nitrogen oxides (N O X ) . The emissions dataset presented for the OTR in the first section below is from the 2002 M ANE-V U (Mid-Atlantic /Northeast Vi sibilit y Union) Version 2 regional haze em issions inventor y

. MA NE- V U is the regional planning organizat ion (RP O) for the mid- Atlantic and Northeast states coordinating regional haze planning activi ties for the region. While the context of the M ANE-VU inventor y is regional haze, it includes inventories of N O X and V OCs that also inform air qualit y planners on s ources importan t to ozone format ion. f To provide a fuller

context of precursor e missions contributing to regional ozone affecting the OTR, the section following the M ANE-V U inform ation presents N O X and V OC emissions inform ation from the 2002 National E missions Inventory (NEI) for states in adjacent RP Os.



### 3.1. E mi ss ions inventor y characteristics in t he OTR

3.1.1. Volatile organic com pounds ( VOCs) Existing em ission inventories generall y refer to VOC s as h yd rocarbons whose volatil it y in the at mosphere makes them particular l y impor tant in enhancing ozone forma tion in the presence of NO X . As s hown in Figure 3-12 , the VOC inventor y for the OTR is domin ated by mobile and area sources. Mo st V OC em issions in the OTR, however, co me from natural s ources, which are not shown in the figure. Among the human- caused V OC em issions, on-road mobi le s ources of VOC s include exhaust emissions from gasoline passengervehicles and diesel- powered heav y- duty vehicles as well as evaporative em issions from transportation fuels. V OC emissions ma y also originate from a variet y of area sources (including solvents, architectura l coatings, and dr y cleaners) as well as from some point sources (e.g., industrial faciliti es and petroleu m refineries).
Naturall y occurring (biogenic) VOC emissions are caused by the release of natural organic compounds from plants in warm weather. Many natural V OCs that contribute to ozone formation are highl y reactive. I soprene, for examp le, is a highly reactive five- carbon natural VOC emit ted from mostl y deciduous trees (e.g., oaks) that pla ys an import ant role in enhancing regional ozone format ion across the eastern U.S. (Trainer et

al. , 1987; Chameid es et al. , 1988). Because biogenic V OC emissions are large and reactive, the y are the most impor tant part of the V OC inventor y for understanding and predicting ozone formation. Biogenic V OCs are not included in Figure 3-12 , but national l y, the y represent roughl y two-thirds of all annual V OC em issions (USEPA, 2006a). M odeling biogenic em issions can be difficult as it requires simula ting biological responses to a range of environm ental conditions, such as leaf tempera ture and the

amoun t of sunlight reaching a leaf surface.

f The description of OTR state inventories d iscussed in the first section does not include t he portion of Virginia i n the Washington, DC metropol itan area. I nfo rmation for Virginia i s in the following section and

comes from the 2002 National Em issions In ventor y

.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2

Figure 3

- 12 . 2002 MA NE-VU s tate VOC inventories in the OTR

0 % 2 5 % 5 0 % 7 5 % 1 0 0 %

C o n n e c t i c u t

D e l a w a r e

D i s t r i c t o f C o l u m b i a M a i n e
M a r y l a n d

M a s s a c h u s e t t s

N e w H a m p s h i r e

N e w J e r s e y

N e w Y o r k

P e n n s y l v a n i a

R h o d e I s l a n d V e r m o n tmilliont/y

0

. 0 0

. 2 0

. 4 0

. 6 0

. 8 1

. 0 1

. 2 1

. 4 1

. 6

A R E A N O N R O A D O N R O A D P O I N T E m i s s i o n

Figur e ke y: Bars = Percenta ge fractions of four source cate gories; Circles = Annual emissions amount i n 10 6 tons per ye ar

. The Virginia port ion of the Wash ington, DC metropolitan area i s not shown in the figur e.


### 3.1.2. Oxides o f nitrogen ( NO X 

### )
NO X emissions are a fundament al necessity for the atmospher ic forma tion of

ozone. Without

NO X , ozone format ion during warm s um me r da ys would virtuall y cease, regardless of the amoun t of reactive V OCs present. B y contrast, without V OCs, N O X would still produce ozone in the presence of sunlight, albeit at a much di minished efficienc y

. Figure 3-13 s hows N O X em issions in the OTR at the state level. Since 1980, nationwide e missions of N O X from all s ources have sho wn littl e change. In fact,

em issions increased by 2 percent between 1989 and 1998 ( USEPA, 2000). This increase is most likel y due to industrial s ources and the transportation sector, as power plant combust ion sources have imple me nted modest emissions reductions during the s am e ti me period. Mo st states in the OTR experienced declining NO X em issions from 1996 through 2002, except Massachusetts, Mar yl and, Ne w York, and Rhode I sland, which sho w an increase in N O X emissions in 1999 before declining to levels below 1996 emissions in 2002.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

Figure 3

- 13 . State level nitrogen oxides em is sions

0

. 0 0

. 2 0

. 4 0

. 6 0

. 8 1

. 0 1

. 2

C o n n e c t i c u t

D e l a w a r e

D i s t r i c t o f C o l u m b i a M a i n e
M a r y l a n d

M a s s a c h u s e t t s

N e w H a m p s h i r e

N e w J e r s e y

N e w Y o r k

P e n n s y l v a n i a

R h o d e Is l a n d
V e r m o n tmilliont/y N E I 1 9 9 6

N E I 1 9 9 9

M V 2 0 0 2 v

. 2

Monitored ambi ent NO X trends during the summ er from 1997 to 2005 corroborate the down ward trend in NO X emissions seen in the em issions inventories for the OTR. As seen in Figure 3-14 , the 24-hour (lower trend lines) and 6 a.m.- 8 a.m. (upper trend lines) NO X concentrations indicat e decreases in NO X over this tim e period in the OTR. The NO X reductions likel y come from decreasing vehicle NO X emissions due to more stringent motor

vehicle standards as well as N O X reductions from the OTR NO X Budget Program and the NO X SI P Call (ma inl y power plants).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

Figure 3

- 14 . Plot of

mo nitored NO X

trend s in OTR d uring 1997-2005

J U NE, J U LY &

AU GUST

1 99 7-2 00 5 O T C A

VER AGE N Ox CON CEN TR AT IONS

10 15 20 25 30 35 40 45 50199719981999200020012002200320042005199719981999200020012002200320042005199719981999200020012002200320042005AverageConcentration (ppb).

JU N (al l hrs) JU L (al l hrs) AUG (all hrs) JU N (06

- 0 8 E ST ) JU L (06-08 E ST ) AUG (06-08 ES T )

Note: Upper trend lin es correspond to ambient NO X measured from 0600- 0800 EST in the mornin g. Lo wer trend lines correspond to NO X measured over entire day (created b y Tom Do wns, Maine Department of Environ mental Protection)

. Power plants and mobil e sources generall y domin ate state and national NO X em issions inventories. Nationall y, power plants account for more than one-quarter of all NO X emissions, amount ing to over six mil lion tons. The electri c sector play s an even larger role, ho wever, in parts of the industrial Midwest where high N O X em issions have a particul arl y significant power plant contribution. B y contrast, mobi le sources domin ate the N O X inventories for mor e urbanized mid- Atlantic and N ew England states to a far greater extent, a s shown in Figure 3-15 . In these states, on-road mobi le sources — a categor y that ma inl y includes highwa y vehicles — represent the most significant N O X source categor y

. Emissions from non-road (i.e., off-highwa y) mobi le s ources, pri maril y diesel- fired engines, also represent a substantial fraction of the inventor y

.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

Figure 3

- 15 . 2002 MANE-VU state NO X inventories in the OTR

0 % 2 5 % 5 0 % 7 5 % 1 0 0 %

C o n n e c t i c u t

D e l a w a r e

D i s t r i c t o f C o l u m b i a M a i n e M a r y l a n d

M a s s a c h u s e t t s

N e w H a m p s h i r e

N e w J e r s e y

N e w Y o r k

P e n n s y l v a n i a

R h o d e I s l a n d V e r m o n tmilliont/y

0

. 0 0

. 3 0

. 6 0

. 9

A R E A N O N R O A D O N R O A D P O IN T E m i s s i o n

Figur e ke y: Bars = Percenta ge fractions of four source cate gories; Circles = Annual emissions amount i n 10 6 tons per ye ar

. The Virginia port ion of the Wash ington, DC metropolitan area i s not shown in the figur e.



### 3.2. E mi ss ions inventor y characteristics ou tside t he OTR
NO X and VO C em issions in the OTR are onl y one component

of the em issions contributing to ozone affecting the OTR. A s regional mode ling for the NO X SIP Call and CAIR have shown, emission sources, prim aril y of N O X , located outside the OTR can significant l y contribute to ozone transported into the OTR. H ere we present regional

em issions informat ion grouped b y the three eastern R

POs – M ANE-V U, VISTA S (Visibilit y Improvem en t State and Tribal A ssociation of the S outheast), and the MWRP O (Midwest RPO). Table 3-3 lists the states in each RPO.
The inventor y informa tion is extract ed from the U SEPA final 2002 National Em issions Inventory (NEI). For consistenc y, the MA NE- V U informa tion here also com es from the 2002 NEI rather than from the M ANE-V U Version 2 regional haze em issions inventor y described above. The differences between the inventories are not great, as the NEI and the MA

NE-VU Ver sion 2 inventor y are both ba sed on the same inventor y inform ation provided b y

the states.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6

Table 3

- 3

. Ea stern U .S. RPOs and t heir state me m b er s RP O State MWR PO Illinois MWR PO Indiana MWR PO Michigan MWR PO O hio MWR PO Wisconsin M ANE-VU Connecticut M ANE-VU Delaware M ANE-VU Di strict of Columbia M ANE-VU Maine M ANE-VU Mary la nd M ANE-VU Ma ssachusetts M ANE-VU Ne w Hampshire M ANE-VU Ne w Jersey M ANE-VU Ne w York M ANE-VU Penn s yl va nia M ANE-VU Rhode Island M ANE-VU Vermont V ISTAS Alabama V ISTAS Florida V ISTAS Georgia V ISTAS Kentucky V ISTAS Mi ssissippi V ISTAS N orth Carolina V ISTAS South Carolina V ISTAS Tennessee V ISTAS Virginia V ISTAS West Virginia

Table 3-4 presents VOC emissions b y source sector and RP O for the eastern United States. The NO X em issions by s ource sector and RPO are presented in Table 3-5

. Regionall y , N O X em issions are more importan t with re spect to regional ozone forma tion and transport. NO X em issions in combin ation with abundant naturall y occurring VOC

em issions from oaks and other vegetation have been shown to be important sources of regional ozone in the eastern U .S. (Trainer et al. 1987; Chameid es et al. 1988).

Table 3

- 4

. VOC em is sions in eastern RPOs RP O Point A rea On-road N on-road Total MWR PO 234,938 1,182,186 660,010 492,027 2,569,160 M ANE-VU 93,691 1,798,158 793,541 494,115 3,179,504 V ISTAS 458,740 2,047,359 1,314,979 609,539 4,430,617The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 7

Table 3

- 5

. NO X

em is sions in eastern RPOs RP O Point A rea On-road N on-road Total MWR PO 1,437,284 184,790 1,290,178 723,844 3,636,096 M ANE-VU 680,975 268,997 1,297,357 534,454 2,781,783 V ISTAS 2,094,228 266,848 2,160,601 812,615 5,334,293



### 3.3. Are NO X 

### or VOC control strategies m ost ef fective at reducing ozone? The effectiveness of a NO X -focused or V OC-focused control strateg y to reduce

ozone is not constant by location or e missions; rather it is a changing chemi cal character istic of an air

parcel affecting a particul ar location. A s a result, the effectiv eness of a N O X or V OC-focused control strateg y can vary within an air parcel as it dy na mi ca ll y evolves over ti me with transport, dispersion, and photochem ica l aging ( NARSTO, 2000). On a regional basis, OTAG, C AIR and other mode ling studies have consistentl y shown that N O X reductions have the greatest impac t on regional ozone concentrations, while V OC reductions have more local imp acts. This is largel y a result of significant naturall y occurring V OC emissions (especiall y isoprene) in large fore sted regions of the eastern U. S. Real- world results from regional NO X reductions at po wer plants (i.e., the NO X SI P Call) are no w indicat ing that significant ozone reductions are occurring on a regional basis as a re sult of regional NO X strategies. A recent U SEPA report finds a strong association between areas with the greatest N O X emission reductions due to the NO X SI P Call and downwind sites exhibiting the greatest improve me nt in ozone in 2005 (USEP A, 2006b). As a general rule, V OC reductions ma y be effective at reducing urban-scale ozone pollution in lieu of or in comb inat ion with local N O X reductions, w hile regional NO X controls are most effective at reducing regional ozone. While a general rule can be outlined in evaluating the potentia l effectiveness of NO X and VO C-focused control strategies, the optim al strategy for a s pecific location will depend on the particular circu mstanc es of that location. Exceptions to a VO C-onl y strateg y for an urban area can
occurw hen the urban area has large natural VOC emissions, ozone is transported from upwind, or there is recircula tion of aged local pollution (e.g., sea breeze effect). Furthermor e, because the conditions causing individual ozone episodes can vary , a given urban area may change in sensitivit y between a NO X and VO C-focused strategy depending on a particul ar episode’s conditions (NAR STO, 2000). Therefore, the appropriate combina tion of V OC and NO X controls at the local level depends on local circu mstanc es with the realizat ion that a single approach focusing on N O X or VOC-only controls is not necessaril y effective for all episode t yp es. It is clear, however, that regional NO X reductions provide regional ozone reductions, and this will influence ozone levels being transported into local urban areas.


### 3.4. Sum m a ry There are large e missions of V OCs and N O X within and outside the OTR that contribute to local and regional ozone proble ms. Naturall y occurring V OC em issions pla y
an importan t role in combin ation with human- caused NO X emissions in form ing regionalThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 8

ozone across large sections of the eastern U.S. Regional N O X control strategies are demonstr ating s uccess in reducing regional ozone. On a more local scale, s om e comb inat ion of VO C and N O X controls ma y be needed, with the specific co mbinat ion dependent upon local circumstan ces.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 9



### References

Cham eides, W.L., R.W. Lindsa y, J . Richardson, and C.S. Kiang. “The role of biogenic h yd rocarbons in urban photoche mic al smog: Atlanta as a case stud y. ” Science 241 , 1473- 1475, 1988.

NAR STO. An As sessment of Troposphe ric Oz one Pollution . NAR STO, Jul y 2000.

Trainer, M., E.J. Willia ms, D. D. Parrish, M.P. Buhr, E.J. Allwine, H.H. Westberg, F.C. Fehsenfeld, and S.C. Liu. “M odels and observations of the impa ct of natural h yd rocarbons on rural ozone.” Nature 329 , 705-707, 1987.

USEP A. National

Air Q uality and Emis sion T

rends Report, 1998 , EPA 454/R-00-003, availab le online: http://www.epa.gov/oar/ aqtrnd98/ , 2000.

USEP A. 2002 Final

National Emissions Inventory (NEI) , availab le online: ftp://ftp. epa.gov/ Em isInven tor y/ 20 02fina lnei / , 2006a (accessed October10, 2006) [The 2002 NEI reports national annual emissions for total anthropogenic V OC em issions as 16.8 mi llion tons, and total biogenic V OC emissions as 41.8 mi llion tons].

USEP A. NO

X Budget Trading Progra m 2005 Compliance and Environmental Results
, EPA430-R-06-013, availabl e online: http://www.epa.gov/ airm ark ets/fednox / , 2006b.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



## 4. WHA T WILL IT T AKE T O CLE AN THE AI R?

– LINKING THE SCIE NCE T O POLIC Y

4.1. The t hree p hases of a bad ozone da y an d the ozone reservoir With the atmospheri c che mistr y, me teorolog y , and air

emission inventor y ele men ts presented in the previous sections, a conceptua l description em erges of ozone proble m in the OTR. Consider a ty pi ca l “day ,” defined as starting at sun set, for a severe

ozone event as sociated with a high pre ssure s ys tem

. Conceptuall y, a bad ozone da y can be con sidered as occurring in three phases. During phase one, a nocturnal inversion forms as the temper ature of the earth drops following s unset, isolating the surface from stronger winds only a fe w hundred feet overhead. Ozone near the s urface cannot mix with ozone above and is destroy ed a s it reacts with the Earth’s surface. In a cit y, fresh N O X em issions react with ozone, further

reducing its concentration, so that by morning, ver y litt le ozone is left below the nocturnal inversion. At this ti me, the nocturnal inversion is at its strongest, and wind s at the s urface are ty pi ca ll y cal m. Above the nocturnal inversion, the situation is quite different. Ozone and its precursors, both from the previous day ’s local emissions and from transport, rema in largel y intact. There are no surfaces to react with the ozone and a large re servoir of ozone

rem ains above the inversion. D uring phase two of a bad ozone day
, the nocturnal inversion breaks down at mid- morning, with the re sult that the ozone and precursors above the inversion can now mix with the air near the surface. The result of this mix ing is

a s udden change in ozone. Figure 4-16 s hows median ozone profiles for morning and afternoon aircraft flights from 1996 – 2003. O ne can clearl y see the breakdown of the nocturnal inversion throughout the da y ( Hudson, 2005).
Figure 4

- 16 . Median ozone pro files for m or ning an d af ternoon flight s f rom 1996 – 2003

O 3 m e d i a n p r o f i l e s f

o r m o r n i n g a n d a f

t e r n o o n f l i g h t s ( 1 9 9 6

- 2 0 0 3 )

0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0 3 0 0 0 3 5 0 0

0 2 0 4 0 6 0 8 0 1 0 0 1 2 0

M e d i a n O 3 ( p p b ) w i t h 25 t h a n d 7 5 t h p e r ce n t i l e sPressurederivedaltitude(m) m e d i a n
a m ( 2 5 4 )

m e d i a n p m ( 2 9 3 ) q 2 5 a m

q 7 5 a m

q 2 5 p m

q 7 5 p m A M P MThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2

In phase three of a bad ozone da y, ozone concentrat ions reach their highest levels in the afternoon through the combin ed accu mula tion of local pollution produced that da y mix ed with the transported regional pollution load brought in overnight from the ozone reservoir. Figure 4-17 show s this graphicall y for the southern OTR. The ozone moni tor at Methodist Hill, P A is a high elevation site located at 1900 ft in alti tude in s outh central Pennsy lv ani a, and is above the nocturnal inversion. In the earl y morning hours of Augu st 12, 2002 (e.g., 5 a.m.), it recorded ozone concentrat ions above 80 ppb, which w as much higher than what other lower

elevation moni tors in the region were recording (e.g., Little Buffalo State Park, P A, South Carroll Count y, M D, Frederick, M D, As hburn, VA, Long Park, VA). D ue to the lack of sunlight necessary to produce ozone photochem ical l y during nighttim e hour s, the high ozone levels seen at Methodist Hill, PA indicate the presence of a significant ozone reservoir above the nocturnal inversion lay er produced during day li ght hours at some earlier point in tim e and transported into the region. With the break up of the nocturnal inversion after s unrise (e.g., starting about 7 a.m.), ozone concentrat ions at the lower elevat ion moni tors s how a rapid increase. This reflects the mix ing down of the ozone reservoir from higher alti tude to the surface in combin ation with local ozone production nearthe surface no w that the sun ha s begun inducing its photoche mi cal production.
Figure 4

- 17 . Hourl y ozone pro files in the southern OTR, A ugust 12, 2002

0 20 40 60 80 100 120 1400:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00

Ho ur ( E ST )Ozone (ppb) So uth Carr o ll, MD F rede r i ck
, MD M eth odis t H i ll, P A Li tt le Buffal o SP, PA As hburn, V A Lon g P ark
, V A

The ozone reservoir

extends across the OTR, as seen on the same night in high elevat ion ozone monitoring sites in the northern OTR. Figure 4-18 show s the hourly

ozone concentrations m easured on August 12, 2002 at Mohawk Mountain, CT, Cadillac Mountain, ME, Mt. Grey lo ck, MA, Mt. M onadanock, NH , Mt. Washington, NH, andThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

Whitefac e Mountain, N Y. As with Methodist Hill, PA on this day
, these sites s how elevated ozone concentra tions during nightti me hours, as compar ed to lower elevation sites below the nocturnal inversion (e.g., Danbur y, CT). By mid- da y, ho wever, the nocturnal boundar y lay er ha s broken do wn, m ixing the transported ozone from the reservoir above into the locall y produced ozone below. Appendix G provides mor e detail on contributions to the ozone reservoir within and outside the OTR.
Figure 4

- 18 . Hourl y ozone pro files in the northern OTR, Augu st 12, 2002

0 2 0 4 0 6 0 8 0 10 0 12 0 14 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00
Ho u r ( E ST)Ozone (ppb)

M ohaw k M t n., C T

M t. M ona danoc k
, NH M t. Grey l ock, MA M t. W a shin gto n, N H W hi tefac e M t n., N Y C a dil lac M tn.
, M E D a nbury
, C T

Data provided b y

Tom Do wns, Maine Department of Environ mental Protection.


### 4.2. Chronology of an ozone episode – August 2002 The chronology of an historical ozone episode occurring in the OTR from August 8 to A ugust 16, 2002 provides a real- w orld exampl e that pieces together the ele men ts of the ozone conceptua l description given in this docu ment. S urface maps from the period provide a s ynop tic overview of major weather sy ste ms that were influencing air qualit y across the OTR during that tim e. Meteorologica l insights combined with ozone concentrat ion inform ation provide a picture of the evolving ozone episode on a day

- by

da y ba sis. Figure 4-19 , Figure 4-20 , and Figure 4-21 , respectivel y , sho w eight- panel displa ys of s urface weather maps, back trajectories, and 8-hour maxi mu m ozone concentrat ions from each da y. The dail y progres sion s hows the forma tion of high ozone that shifts from w est to east, and ultim ate l y northward, during s uccessive day s of the episode according to local ozone format ion and transport shaped b y wind patterns within and outside of the OTR.
The Augu st 2002 episode began with a slow-moving high pres sure sys te m centered over the Great Lakes initi ating a northerl y flow over the OTR on A ugust 8. OverThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

the next several da ys , the high drifted southeastward and became extended across a large part of the eastern U.S., bringing high temper atures to the region. Calm conditions we st of the OTR on Augu st 10 w ere pivotal for the formation of ozone, which first began building in the Ohio River Valle y. O ver the next

four day s, 8-hour ozone concentrat ions cli mbed well above the 85 ppb (0.08 ppm) N AA QS over a wide area of the OTR. Large parts of the heavil y populated Northeast Corridor experienced 8-hour ozone levels above 100 ppb during the height of the episode, which far exceeded the 85 ppb N AA QS.
The following chronology provides a day

- by

- day evolution of the Augu st 2002

ozone episode. Parts of this description are taken from R ya n (2003). Augu st 8: A high pres sure sys te m over the G reat Lakes produces NW-N prevailing s urface winds (~4-8 mph) throughout the region. Maximu m dail y temper atures approach or exceed 80 o F. Augu st 9: Wind speeds fall off but the direction remains NW-N as the high

moves into the Penn s yl va nia- Ne w York region. Te mpera tures rise as cloud cover declines. Background ozone levels begin to build in the O hio River Valle y with 8-hour

max im um concentrations reaching the 60-80 ppb range. Augu st 10: High pres sure is directl y over the mid- Atlantic. With dew points still in the mid- 50 o’s F , the skies are extraordinar il y clear throughout the day

. Temper atures (except in northern-most areas) approach 90 o F while s urface- level winds turn to more southerl y directions. With high pressure overhead, the back trajectories s uggest very light winds and recircula tion. Calm conditions through the morning hours in the lower O hio RiverValle y promote increasingl y higher levels of ozone noted in surface observations – now reaching above the 85 ppb 8-hour ozone N AA QS over mu ch of Indiana, Ohio, and other states along the O hio River, as well as states around Lake Michigan and large portions of the southeastern U. S. Ozone levels above the 8-hour NA AQS now begin appearing for the first ti me in the western and southern parts of the OTR. Augu st 11: Surface high pres sure drops slowly southeastward acros s the midAtlantic with the center

in western North Carolina drifting to coastal South Carolina during the da y. The upper level ridge has also mov ed east and is located over the midAtlantic. Circulation around the high becomes w ell established. A surface-level trough descends from north of the G reat Lakes during the day
, pas ses eastward through the O hio RiverValle y and stalls over the Alleghen y Mountains and s outhward. Peak temp eratures

are in the low to mid- 90 o’s F. M orning wind s are low-to-cal m in the area east of the Missis sippi – the area of ozone no w reaches from eastern Wisconsin to Tennessee and eastward to Georgia up through the Carolinas into the OTR, covering most of Pennsy lv ani a, New Y ork, New Jersey
, Connecticut, Rhode I sland and Massachusetts. Winds are generall y south to s outhwest as is reflected in the boundar y

la y er back trajectories . The key factor driving local ozone production appears to be a ver y stable boundar y lay er

. The 8 a.m. s ounding at the Washington- D ulles airport s hows a very strong low-level inversion from 950-900 mb with a deep residual lay er beneath a continuing strong s ubsidence inversion – no w based at 760 mb. Augu st 12: The upper

level ridge rem ains quasi-stationar y with its axis over the mid- Atlantic. The center

of high pressure at 850 mb is over N orth Carolina and Georgia. At the surface, the characterist ic Appalachian lee side trough forms. Te mperatur es exceedThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

90o F throughout the OTR except in coastal Maine. Winds are fairl y strong from the northwest. This is reflected in the back trajectories that s how a shift to westerly transport. Elevat ed upwind ozone concentrations at 11 a.m. on August 11 occur in the vicini t y of the origin of the back

trajectories, on the order of 78-86 ppb. Ozone concentrations fall this day we st of the Appalachians but increase markedl y across the mid- Atlantic. The

area of highest ozone has pushed eastward and no w extends from southern Maine across central Penn s yl van ia do wn through M ar yl an d into the Carolinas, Georgia, and eastern Tennessee. Ozone builds throughout the day as circulation forces it to channel northeast between the stalled trough and a cold front approaching from the Mid west. Some of the highest 8-hour concentrations occur through the central to s outhern OTR on this da y. Augu st 13: Calm conditions prevail as the trough reaches coastal New Jersey by 8 a.m. Generall y clear

skies allow tempera tures to reach the mid- 90 o’ s F ever yw here except in coastal Maine. Dew points, which had been rising since Augu st 8, reach the upper 60 o’ s F. A morning sounding at the Washington-Dulles airport s howed a continuing strong low level inversion with a residual mixed lay er to 850 mb ending j ust beneath a weak secondary inversion. The cap aloft has lifted to ~ 630 mb and the sounding is more unstable compared to previous da y’ s between the two inversion la ye rs. The Appalachian lee side trough continues in place from late on August 12 . As is t yp ic al l y the case, the highest ozone concentrations are found in proxim it y to this boundar y. The highest 8-hour ozone concentrat ions are along the eastern portions of the OTR from northeastern Virginia through New J erse y, Long I sland, Connecticut, and into eastern Mas sachusetts. B y 8 p.m., showers as sociated with the approaching cold front have reached into Ohio. Augu st 14: By 8 a.m., the trough has dissipated and the high is moving offshore, resulting in an increasing southerly wind co mponent, w hich pushe s m arit im e air northward. D ew points re main in the upper 60 o’s F and peak te mperatur es reach into the 90o ’s F every

wh ere and top 100o F in several locations. Ozone concentra tions build again, with the highest levels concentrated in the central OTR from eastern Pennsy lv ania across to Ma ssachusetts. A “hotspot” of ozone appears in upstate New Y ork at the eastern end of Lake Ontario, and ma y be the result of transport from the west across the lake. Ozone concentrat ions decrease south and west of Balti more and along coastal Ne w Jersey as cleaner marit im e air pushes in from the south.
Augu st 15: This episode ends in a ver y different manner

than the standard high

ozone episode. Instead of the passage of a s harp cold front, this episode ends graduall y as cleaner air sweeps north, winds increase, and the atmosphere steadil y destabilizes. Ozone concentrat ions fall across the midd le and lower OTR as low level flow becom es more southeast and the Bermuda high fills in we stward. The highest levels, still exceeding the 8-hour ozone N AA QS, now occur in the northern reaches of the OTR in upstate New York, Vermont, N ew Hampshire, and Maine.
Augu st 16: Cloud cover

s preads over the region with ozone falling further. The new high building into the upper Midwest pushes the rema ins of the s howers out of the Northeast. A spot of high ozone persists in central New J erse y. This is the last exceedanc e da y

in a string of seven exceedanc e da ys within the OTR during this extended episode.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6

Figure 4

- 19 . Sur face w e at her m ap s fo r Augu st 9-16, 2002

Au g us t 9 , 8 :0 0A M E DT Au g us t 1 0, 8 :00 AM E D T

Au g us t 1 1, 8 :00 A M E D T Au g us t 1 2, 8 :00 AM E D T

Au g us t 1 3, 8 :00 A M E D T Au g us t 1 4, 8 :00 AM E D T

Au g us t 1 5, 8 :00 A M E D T Au g us t 1 6, 8 :00 AM E D TThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 7

Figure 4

- 20 . HYSPLIT 72-hour back trajectories f or Au gust 9-16, 2002
Aug 9 , 2002 8 am ED T , 2002 8 Aug 10, 2002 8 am ED T

Aug 1 1 , 20 02 8 a m E D T Aug 12, 2002 8 am ED T

Aug 1 3 , 20 02 8 a m E D T Aug 14, 2002 8 am ED T

Aug 1 5 , 20 02 8 a m E D T Aug 16, 2002 8 am ED TThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 8

Figure 4

- 21 . S patially interpolated m ap s of ma xim u m 8-hour sur face ozone concentrations A ugust 9 – 16, 2002The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 9



### 4.3. Clean Air Act provisions As is evident from the m yr ia d s ource regions and transport pathway s affecting the OTR, the regional ozone nonattainm ent problem presents a significant challenge to air qualit y planners. To i mprove air qualit y, em ission reductions of the appropriate pollutants must occur at the appropriate levels (i.e., stringenc y of controls) and over the appropriate geographic extent. States have primar y re sponsibilit y for achieving the goals of the Clean Air Act, a s the y are re sponsible for developing State Impl em ent ation Plans and imp le me nting and enforcing emission reduction programs to me et the health- protective National Ambi ent Air Qualit y Standards ( NAA QS).
When Congres s passed the Clean Air Act Amendm en ts of 1990, it recognized that air pollution transcends political boundaries and that tools for addressing transport must be made availab le to state and federal governmen ts. Accordingl y, s everal Clean Air Act provisions deal with transported pollution, including: (1) prohibiting the USEP A from approving State Imple me nta tion Plans that interfere with another state’s abilit y to attain

or ma inta in a NA AQS; (2) requiring the U SEPA to work with states to prevent emissions that contribute to air

pollution in a foreign countr y; (3) allowing states to form ozone transport regions; (4) requiring states in ozone transport regions to adopt a prescribed set of controls in order to achieve a m inim um level of regional em ission reductions; and (5) allowing states to petition the USEP A for ti mel y relief from stationar y s ource emissions that interfere with attainm en t or ma inten ance of a N AAQ S, and requiring the USEP A to act on such petitions within a ver y short, prescribed ti mefra me

. Taken together, these provisions provide a framework for air qualit y planning. Its inherent principles are:

• Ti mel y action is critica l in order to protect

public health;

• States must

act locall y to address air pollution;

• While acting locall y, states must also considertheir

impac ts do wnwind in addition to in-state impac ts when developing state impl em en tation plans (SIP s), and

am elior ate s uch impac ts through SIP s;

• Regional actions have been and can continue to be effective;

• To be effective on a regional level, states w orking together must work off of a level pla y in g field.
What the science tells u s of the nature of the ozone problem in the OTR s upports this framework. The smaller scale weather patterns that affect pollution accumul ation and transport underscore the import ance of local (in-state) controls for N O X and VO C

em issions. Larger s yn optic scale weather patterns, and pollution patterns as sociated with the m, support the need for NO X controls across the eastern U nited States. Studies and character iza tions of nocturnal low level jets (i.e., channeled transport) also s upport the need for local and regional controls on N O X and V OC sources as local and transported pollution from outside the OTR can be entrained in nocturnal low level jets formed during nighttim e hour s within the OTR. Land, sea, mount ain, and valle y breezes indicate that there are unique aspects of pollution accumu lat ion and transport that are area- specific and will warrant polic y respon ses at the local and regional levels bey ond a one-size- fitsall approach.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 10

The mix of emission controls is also import ant for states to consider. While longrange transport of ozone is primar il y due to NO X , VOC s are import ant because the y contribute to ozone formation by influencing how efficient l y ozone is produced b y NO X , particul arl y within urban centers. While reductions in anthropogenic V OCs will t yp ic al l y have less of an impa ct on the long-range transport of ozone, the y can be effective in reducing ozone in those urban areas where ozone production m a y be li mit ed b y the availab ili t y of VO Cs. Therefore, a comb inat ion of localiz ed VOC reductions in urban centers with additiona l NO X reductions (from both mobi le and point sources) across a larger region will help to reduce ozone and precursors in nonattainm en t areas as well as their downwind transport across the entire region ( NESCAU M, 1997).



### 4.4. Past regional ef

forts While states are somewhat lim ited in their abilit y to directl y affect emissions reductions be yo nd their

own geo-politic al boundaries, over the past 15-20 ye ar s, the Northeast states have acted regionall y with tremendous s uccess. Such efforts have included:

• In 1989, regional low volati lit y gasoline (i.e., Reid Vapor P ressure pf 9.0 psi) was introducedinto the NE SCAU M region, resulting in significant V OC reductions;

• In 1994, the California Low E mission Vehicle (LEV) progra m com me nced in the Northeast Corridor as regulations were adopted b y Maine, Ma ssachusetts, Ne w York, and Vermont. To date, four additional states have j oined the program, which continues to yi el d reductions in N O X , VOC, C O, and air toxics.

• In 1994, the states of the Ozone Transport Comm ission agreed to promu lgate regional NO X R

ACT controls and a N O X cap- and-trade program. The adopted regional RACT deadline wa s 1995. B y 1999, the NO X Budget Program was imp le me nted over the 12-state region from Maine to Washington, DC. In 2002, the U SEPA reported that the NO X Budget sources “emit ted at a level approxi mat el y 12 percent below 2001 allocations” ( USEPA, 2002). Progres s continues with a more stringent cap taking effect in 2003.

• In 1997, eight OTR states petitioned the USEP A under s ection 126 of the Clean Air Act, requesting NO X emissions reductions on certain stationar y sources in the Eastern U.S. In 1999, four more OTR me mb ers filed section 126 petitions. The USEP A granted four of the initial eight state petitions in 2000. g

• In 2001, the states of the Ozone Transport Comm ission agreed to support a s uite of mode l rules for inclusion in S IPs as appropriate to addres s 1-hour ozone proble ms. The mod el rules included controls for: (1) architectura l and industrial

ma inten ance coatings; (2) portable fuel containers; (3) consumer products; (4) solvent cleaning; (5) mobile equipm ent repair and refinishing; and (5) additional NO X controls for industrial boilers, ce ment kilns, stationar y reciprocat ing engines, and stationar y combustion engines.

g The in itial eight section 126 OTR states were C onnecticut, Maine, Massachusetts, New Hampshire, New York, Pennsy lvani a, Rhode I sland, and Vermont. The additional four OTR me mbers filing section 126 petitions were Delawar e, the District of C olumbia, Mar yl and, and New Jersey

. The four gr anted petitions

were from Connecticut, Massachusetts, New York, and Pennsy lv ania.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 11

These regional efforts have led the way for simil ar broader regional and national programs. F or mobi le s ources, the U SEPA promulg ated its federal Reformul ated Gasoline Program in 1995 and the National LEV program in 1998. F or stationar y sources, the U SEPA announced in 1997 that it w ould expand the OTR N O X Budget Program through the N O X SI P Call, which included 22 states and NO X caps in place b y 2003. The N O X SIP Call also served as a response to the states’ Section 126 petit ions under the Clean Air Act. In 2005, the U SEPA took a further step to address the regional ozone problem by issuing the Clean Air Interstate Rule (C AIR), which requires additional N O X reductions in 25 eastern states and the Di strict of Columbia. The USEPA pro jects that CAIR will achieve N O X reductions of 2 mill ion tons in 2015, a 61% decrease from 2003 levels. This will be a significant step forward in i mproving air qualit y , but the ti me allowed to achieve these reductions is later

than the deadline man y eastern states are facing to mee t the current 8-hour ozone N AA QS. This, therefore, onl y partiall y provides the OTR with a regional m easure that helps achieve the Clean Air Act’s goal of attaining the ozone air qualit y health standard within the Act’s mand ator y deadlines.



### 4.5. Sum m a ry: Building u pon success A conceptual understanding of ozone as a regional proble m in the OTR and throughout the eastern U.S. is no w well established. With this evolution in understanding, regional approaches to the ozone problem are now underway
, starting with the 1990 Clean Air Act Amend me nts that created the Ozone Transport Region. This initial regional approach, however, did not include large source regions outside of the OTR containing man y large coal- fired po wer plants and other pollution sources contributing to the long-range transport of ozone into the OTR. In 1998, the U SEPA took another step in addressing the regional problem by finaliz ing the N O X SIP Call, w hich covered emissions of N O X , the main precursor of regional ozone, in additiona l parts of the East. Even with these reductions, air qualit y mode ling ha s projected continuing significant contributions from upwind sources in outof-state regions. As a result, the USEP A promulg ated a further round of regional N O X reductions in the East with the adoption of CAIR in 2005. With the model ing foundation for CAIR, the U SEPA has presented a compel ling technic al case on the need for additiona l regional NO X reductions in the eastern U.S. to reduce ozone levels and protect public health. While states in the Northeast disagree with the extent of NO X reductions and the ti mel ine for those reductions to occur, the program is an excellent next step toward reducing ozone in the OTR.
There is a tendenc y to characteriz e the nonattainm en t proble ms persisting after imp le me nta tion of the U SEPA’s Clean Air Interstate Rule and other federal programs as “re sidual,” but care must

be taken in assessing these continuing nonattainm en t proble ms. A “ residual” ozone problem is better characteri zed as a persistent nonattain me nt problem that still requires broad regional responses coupled with local controls. A s this conceptual description points out, one of the great lesson s and s uccesses seen in the histor y of air qualit y policy was the s hift from urban- only air pollution control strategies to broader regional approaches in the East at the end of the 1990 s (e.g., N O X SI P Call). The dangerThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 12

exists, ho wever, that the perception of a “ residual” ozone problem as being onl y a local issue will ignore the lessons learned from effective regional approaches.
The current s uite of local and regional controls have a proven track record of success, and have helped to significantl y lower NO X , VOC, and ozone levels across the eastern U. S. As described earlier in this report, moni tored NO X emissions and amb ient concentrat ions have dropped between 1997 and 2005, and the frequency and magnitud e of ozone exceedances have declined within the OTR. To maint ain the current mom en tum for improv ing air

qualit y so that the OTR states can me et their attain me nt deadlines, there continues to be a need for mor e regional NO X reductions coupled with appropriate local NO X controls and regional and local VOC controls.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 13



### References

Hudson, R. “ A Conceptual Model for Ozone Transport.” Universit y of Mary la nd, Dept. of Atmospheri c and Oceanic Science. Prepared for the O zone Transport Com mission. Draft N ov. 29, 2005.

NESCA UM. The Long Range T ranspo rt of Oz one and Its Precur

sors in the Eastern United States . NESCA UM, Boston, MA , p.6, 1997.

R ya n, W.F. Air Quality Forecast Report Philadelph ia Forecast Area 2002 . The Pennsy lv ani a State Universit y, Departmen t of Meteorolog y, University Park, PA, March 2003 (availab le on-line at http://www. met eo.psu.edu/~wfr ya n/ phl_2002_f

inal_r eport.ht m ).

USEP A. OTC N

O X Budget Prog ram Compliance Report 2001 . U.S. Environmen tal Protection A genc y, Washington, D C, p. 1, 2002.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



# Appendix A: USEPA Gu idance on Ozone Conceptual Des crip tion

From “G uidance on the U se of M odels and Other Analy ses in Attain ment Demonstra tions for the 8-hour Ozone N AAQ S,” U .S. Environm enta l Protection Agenc y, EPA-454/R-05-002, Section 8, October 2005.

Note: At the ti me of this writing, the USEP A was incorporating Section 8 of the 8-hour

ozone guidance into a new U SEPA guidance documen t covering ozone, PM 2 .5 , and regional haze. The new draft guidance is in Section 11 of D raft 3.2 “ Guidance on the Use of Models and other Analy ses for Demonstrat ing Attain ment of Air Qualit y G oals for Ozone, PM 2 .5 , and Regional Haze,” U. S. EPA, (Draft 3.2 – Septe mber 2006), availab le at http://www.epa.gov/ ttn/scra m/ guid ance_sip.h tm #pm 2.5 (accessed Oct. 5, 2006). The newer guidance, w hen finaliz ed, ma y differ in s ome respects from the text given in Section 8 of the earlier

ozone guidance.

Excerpt of Section 8 from EP A 8-hour ozone N AAQ S guidance docu ment:

8.0 How D o I Get Started? – A “Conceptual Description” 8.1 What Is A “Conceptual Description”? 8.2 What T yp es Of Analy ses Might Be Useful For Developing And Refining A Conceptual Description? 8.2.1. Is regional transport an import ant factor affecting the nonattain me nt area? 8.2.2. What t yp es of me teorolog ica l episodes lead to high ozone ? 8.2.3. Is ozone li mi ted b y availab ili t y of VO C, NO X or combina tions of the two ? Which source categories m a y be most importan t?The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2



## Appendi x A: US E P

A Gu idance on O z one Conceptual Descript ion

8.0 Ho w Do I Get Started? - A “Conceptual D escription” A State/Trib e should start developing informa tion to s upport a model ed attain me nt demonstr ation by as semb ling and reviewing available air qualit y , emissions and

me teorolog ical data. Baseline design values s hould be calculat ed at each ozone moni toring site, as described in Section 3. If past mode ling has been performed, the

em ission scenarios exa mined and air qualit y predictions ma y also be useful. Readil y availab le inform ation should be used b y a State/Tr ibe to develop an initial conceptual description of the nonattain me nt proble m in the area which is the focus of a model ed attain me nt demonstrat ion. A conceptual de scription is instrument al for identif yi ng potentia l stakeholders and for developing a modeling /anal y si s protocol. It ma y also influence a State’s choice of air qualit y mod el, mode ling domain, grid cell size, priorities for qualit y a ssuring and refining emissions estim ates, and the choice of initia l diagnostic tests to identif

y potential l y effective control strategies. In general, a conceptual description is useful for helping a State/Trib e identif y priorities and allocate resources in perform ing a mod eled attainm en t demonstra tion.

In this Section, w e identif y key parts of a conceptua l description. We then present

exa mples of anal y ses w hich could be used to describe each of these parts. We note that initia l anal y ses ma y be co mple me nted later by additional efforts performed by those imp le me nting the protocol.

8.1 What Is A “Co nceptual De scription”?

A “ conceptual description” is a qualitative way of characteri zing the nature of an area’s nonattainm en t proble m. It is best described b y identif y in g key compon ents of a description. Exa mples are listed below. The examp les are not necessaril y comprehensiv e. There could be other

features of an area’s problem which are importan t in particular cases. For purposes of illustration later in the discus sion, we have answered each of the questions po sed below. O ur responses appear in parentheses.

1. Is the nonattainm ent problem primar il y a local one, or are regional factors impor tant?
(Surface measure me nts suggest transport of ozone close to 84 ppb is likel y. There

are s om e other

nonattainm en t areas not too far distant.)

2. Are ozone and/or precursor concentra tions aloft also high?
(There are no s uch measurem en ts.)The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

3. Do violations of the N AA QS occur at several moni toring sites throughout the nonattain me nt area, or are the y confined to one or a smal l number of sites in proxim it y to one another?
(Violations occurat a limi ted numb er of sites, located throughout the area.)

4. Do observed 8-hour dail y maxi mu m ozone concentrat ions exceed 84 ppb frequentl y or ju st on a few occasions?
(This varies among the moni tors from 4 ti mes up to 12 times per ye ar .)

5. When 8-hour dail y maxi ma in excess of 84 ppb occur, is there an
acco mpan y in g characterist ic spatial pattern, or is there a variet y of spatial patterns?
(A variet y of patterns is seen.)

6. Do monitor ed violations occurat locations s ubject to mesoscale wind patterns (e.g., at a coastline) w hich ma y differ from the general wind flow?
(No.)

7. Have there been any recent major changes in emissions of VO C or NO X in or

nearthe nonattain me nt area? If s o, what changes have occurred?
(Yes, several local measures [include a list] believed to result in major reductions in V OC [quantif

y in tons per sum me r da y] have been imp le me nted in the last five y ea rs. Additional l y, the area is expected to benefit from the regional NO X reductions from the NO X SIP call.)

8. Are there discernible trends in design values or other air qualit y indicators which have acco mpanied a change in em issions?
(Yes, design values have decreasedb y about 10% at four sites over the past [x] y ea rs. Sma ller or no reductions are seen at three other sites.)

9. Is there any apparent spatial pattern to the trends in design values?
(No.)

10. Have a mbient

precursor concentrat ions or measured V OC species profiles changed?
(There are no measurem en ts.)The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

11. What past mode ling has been performed and what do the results suggest ?
(A regional mode ling anal y sis has been perform ed. Two em ission scenarios were mode led: current emissions and a substantial reduction in NO X em issions throughout the regional domain. Reduced NO X emissions led to sub stantia l predicted reductions in 8-hour dail y maxi mu m ozone in most locations, but changes near the most

populated

area in the nonattainm en t area in question were smal l or nonexistent.)

12. Are there an y

distinctiv e me teorologi cal measure me nts at the surface or aloft which appear to coincide with occasions with 8-hour dail y maxi ma greater than 84 ppb?
(Other than routine soundings taken twice per day
, there are no me asurem ents aloft. There is no obvious correspondence with me teorolog ical measure me nts other than dail y max im um temp eratures are alwa ys > 85 F on these da ys .)
Using response s to the preceding questions in this exa mple, it is possible to construct an initia l conceptual description of the nonattainm en t area’s ozone problem. First, responses to questions 1 and 11 s uggest there is a significant regional compon ent to the area’s nonattain me nt problem. Second, respon ses to questions 3, 4, 7, 8, and 11 indicat e there is an impor tant local componen t to the area’s nonattain me nt problem. The responses to questions 4, 5 and 12 indicate that high ozone concentrat ions ma y be observed under several sets of me teorolog ica l conditions. The re sponses to questions 7, 8, and 11 s uggest that ozone in and near the nonattainm ent area ma y be re sponsive to both VOC and N O X controls and that the extent

of this response ma y vary s patial l y. The response to question 6 suggests that it ma y be appropriate to develop a strateg y u sing a mode l with 12 km grid cells.

The preceding conceptual description impl ies that the State/Tribe containing the nonattain me nt area in this examp le will need to involve stakeholders from other, nearby States/Trib es to develop and imp lem en t a modeling /ana l ys is protocol. It also suggests that a nested regional mode ling anal y sis will be needed to address the proble m. Further, it

ma y be necessar y

to model at least

several distinctive ty

pes of episodes and additiona l anal y ses will be needed to select episodes. Finall y, sensitivit y (i.e., diagnostic) tests, or other model ing probing tools, will be needed to as sess the effects of reducing VO C and NO X emissions separatel y and at the same ti me.

It s hould be clear

from the preceding examp le that the initial conceptual description of an area’s nonattain me nt problem m a y draw on readil y availabl e inform ation and need not be detailed. It is intended to help launch develop ment and imp le me nta tion of a modeling /ana l ys is protocol in a productive direction. It will likel y be supplem ented by s ubsequent, more extensive modeling and ambi ent analy ses performed b y or for those imple me nt ing the modeling /ana l ys is protocol discus sed in Section 9.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

8.2 What Ty pes O f An aly ses Might Be U sef ul For Developing A nd Refi ning A Co nceptual De scription?
Questions like those posed in Section 8.1 can be addressed using a variet y of anal y ses ranging in complex it y from an inspection of air qualit y data to sophisticated

ma them at ic al analy ses. We anticip ate the simp ler anal y ses will often be used to develop the initial conceptual description. These will be followed by more comp lex approaches or b y approaches requiring more extensive data bases as the need later beco mes apparent. In the following paragraphs, we revisit key parts of the conceptual de scription identified in Section 8.1. We note anal y ses w hich ma y help to develop a de scription of each part. The list serves as an illustration. It is not necessaril y exhaustive.

8.2.1. Is regional tran sport an i mp ortant fa ctor a ff ecting the nonattain me nt area?

- Are there other

nonattainm en t areas within a da y’ s transport of the nonattain me nt area?

- Do “ upwind” 8-hour dail y max im um ozone concentra tions approach or exceed 84 ppb

on some or all of the da ys with observed 8-hour dail y max im a > 84 ppb in the nonattain me nt area? - Are there major

sources of emissions upwind ? - What is the size of the do wnwind/upwind gradientin 8-hour dail y max im um ozone concentrat ions compar ed to the upwind values? - Do ozone concentra tions aloft but within the planetar y boundar y la ye r approach or exceed 84 ppb at night or in the morn ing hours prior to breakup of the nocturnal s urface inversion? - Is there a significant po sitive correlat ion between observed 8-hour dail y maxi mu m
ozone concentrations at most mon itoring sites within or near the nonattainm en t area? - Is the timing of high observed ozone consistent with impa cts esti mated from upwind

areas u sing trajectory mod els? - Do available regional mode ling simu lations s uggest that 8-hour dail y max im um ozone concentrat ions within the nonattain me nt area respond to regional control measures? - Does source apportion ment model ing indicate significant contributions to local ozone from up wind emissions?

8.2.2. What ty pes o f m et eorological episo des lead to high ozone?

- Exa mine the spatial patterns of 8-hour dail y max im a occurring on day s w here the ozone is > 84 ppb and tr y

to identif y a li mit ed number

of distinctive patterns. - Review sy

nopt ic weather

charts for day s having observed concentrat ions > 84 ppb to identif y classes of sy nopti c scale features corresponding to high observed ozone. - Perform statistical anal ys es between 8-hour dail y maxi mu m ozone and me teorologi cal

me asurem ents at the s urface and aloftto identif y distinctive classes of day s corresponding with observed dail y max im a > 84 ppb.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6

8.2.3. Is ozone li mited b y availability of V OC, NO X

or com bi nations o f the t wo ? Which so urce categories ma y be mo st i mp ortant?

- What are the major

source categories of V OC and NO X and what is their relative impor tanc e in the most

recent inventor y ? - Review results from past modeling anal ys es to as sess the likelihood that ozone in the nonattain me nt area will be more responsive to VOC or N O X controls. Do conclusions

var y for different locations? - Apply mode ling probing tools (e.g., source apportionm ent mod eling) to deter mine which s ource sectors appear to contribute most to local ozone format ion. - Apply indicator s pecies me thods s uch as those described by Sillman (1998, 2002) and Blanchard (1999, 2000, 2001) at sites with appropriate measure me nts on da ys with 8- hour dail y max im um ozone exceedanc es. Identif y classes of day s w here further ozone forma tion appears lim ited by available N O X versus classes of day s where further ozone forma tion appears lim ited by available V OC. Do the conclusions differfor different da ys? Do the results differ on w eekda ys versu s weekends? - Apply receptor

mode ling approaches such as those described b y Watson (1997, 2001), Henr y (1994) and Henr y

(1997a, 1997b, 1997c) to identif y source categories contributing to ambien t VO C on da ys with high observed ozone. D o the conclusions differ on da ys when me asured ozone is not high ?

Additional analy ses ma y be identified as is sues arise in impl em en ting a mode ling/ anal y si s protocol. These anal ys es are intended to channel resources availab le to support mode led attain me nt demonstra tions onto the most productive paths po ssible. The y will also provide other pieces of informat ion which can be used to reinforce conclusions reached with an air qualit y mode l, or cause a reasses smen t of assumptions mad e previousl y in appl yi ng the model. As noted in Section 4, corroboratory anal y ses should be u sed to help assess w hether a simul ated control strateg y is s ufficient to mee t the N AAQ S.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 7



### References

Blanchard, C.L., F .W. Lurmann, P .M. Roth, H.E. Jeffries and M . Korc. “The use of amb ient data to corroborate anal ys es of ozone control strategies.” Atmos. Envt. 33 , 369- 381, 1999

. Blanchard, C. L. “ Ozone process insights from field experimen ts

– Part III: Extent of reaction and ozone form ation.” Atmos. Envt. 34 , 2035-2043, 2000.

Blanchard, C. L., and T. Stoeckenius. “O zone re sponse to precursor controls: comparison of data anal ys is methods with the predictions of photoche mi cal air qualit y simu lat ion mode ls.” Atmos. Envt. 35 , 1203-1216, 2001.

Henr y, R.C., C.W. Lewis, and J. F. Collins. “V ehicle- related hy dro carbon source composi tions from ambien t data: The G RACE/SAFER Method.” Envtl. Sci. & Technol. 28 , 823-832, 1994.

Henr y, R.C. “Receptor M odel A pplied to Patterns in S pace (RM APS) Part I. Model description.” J. Air & Waste Mgmt. Assoc. 47 , 216-219, 1997a.

Henr y, R.C. “Receptor M odel A pplied to Patterns in S pace (RM APS) Part II. Apportionm ent of airborne particul ate s ulfur from Pro ject M OHA VE.” J. Air & Waste Mgmt. Assoc. 47 , 220-225, 1997b.

Henr y, R.C. “Receptor M odeling Applied to Patterns in Space (RMAP S) Part III. Apportionm ent of airborne particul ate s ulfur in western Washington State.” J. Air & W aste Mg mt. As soc. 47 , 226-230, 1997c.

Sill man, S . “Evaluating the Relation between Ozone, NO X and Hy drocarbons: The Method of P hotoche mi cal Indicators.” EPA/600R-98/022, http://wwwpersonal.engin.u mi ch.edu/~si llm an /publ icat ions.htm , 1998.

Sill man, S ., and D . He. “S ome theoretica l results concerning O 3 -NO X -V OC chem istr y and N O X -V OC indicators.” J. Geophys. Res. 107 , 4659-4673, 2002.

Watson, J .G. “O bservational Models: The Use of Chemi cal Ma ss Balance Methods.” Prepared for the U.S. EPA S ource Attribution Workshop, Research Triangle Park, NC, July 16-18, 1997, availab le at http://www.epa.gov/t tn/fac a/stissu.ht ml
, Source Attribution Workshop Materials, 1997.

Watson, J .G., J.C. Cho w, and E.M. F ujita. “ Review of volati le organic compound s ource apportion men t b y

chem ica l mass balance.” Atmos. Envt. 35 , 1567-1584, 2001.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



# Appendix B: Ozone patte rn cla ssi fica tions

i n the OTRThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2



## Appendi x B: O z one pattern clas sif ication s in the OTR

The following five t yp es of ozone patterns in the OTR are taken from: Stoeckenius, T. and K emb all- Cook, S . “Determin ation of representativeness of 2002 ozone season for

ozone transport region SI P mod eling.” Final Report prepared for the O zone Transport Com mission, 2005. Figure B-1 show s the 850 mb height and wind fields and Figure B-2 show s the surface te mpera tures and 10 me ter wind fields for the five patterns (reproduced from Figures 3-2 and 3-5 of Stoeckenius & Kembal l- Cook, 2005).
“Type A”

– High ozone throughout the OTR. This pattern is character ized by strong high pressure over the southeastern states extending from the surface to 500 mb with high te mpera tures extending into Ne w England and s outhwest surface winds throughout the OTR. The 850 mb te mperatur es and heights, and surface te mpera tures are above average at all locations except Washington DC; winds are southwest to west throughout the OTR except more variable at LaGuardia and magn itudes of resultant wind vectors are higher than average (indicative of a fairl y stead y, well defined flow regim e), east- we st s urface pressure gradients are near neutral but southwest-northeast gradients along the I-95 corridorand in the west (Pittsburgh to Buffalo) are po sitive, w hich is consistent with the southwest flow. The stable air mass and high temper atures promo te ozone format ion throughout the OTR under these conditions.
“Type B”

– High ozone confined to the extreme southeastern OTR. This pattern is character ized by an upper-level trough off shore of the OTR and a s urface high centered

over K entuck y

. This results in cooler air advection over nearl y all of the OTR with northwest flow aloft and a more w esterl y flow at the surface. The 850 mb heights are lower than average (especiall y in New England) and surface winds are mor e frequentl y from the northwest along the I-95 corridor than under T yp e A . Te mpera tures at 850 mb along the I-95 corridor

are only slightl y cooler

than under

Ty pe A but inland te mpera tures, especiall y in the north, are much cooler (e.g., at Buffalo); similar l y, surface te mpera tures along the I-95 corridor are about the same as under T yp e A but te mpera tures are cooler

in Buffalo and Alban y. Ty pe B events have the strongest positive west-east s urface pressure gradients of any categor y , consistent with the northwest winds but gradients from Washington to New Y ork and Boston are positive. The cooler air over the we stern OTR and westerl y to northwesterl y flow result in the higher ozone levels being confined to ju st the extrem e southern portion of the OTR under this pattern.
“Type C”

– High ozone along the I-95 corridor and no rthern New England. This pattern is character ized by an extension of the semi- perman ent Bermud a high into the southeastern U. S. and an area of high surface and 850 mb temp eratur es extending from Mar yl and to Maine; the 500 mb pattern is nearl y zonal (east-west flow) while flow at the surface is generall y from the southwest. The 850 mb heights are interm edi ate between T yp e A and Ty

pe B but 850 mb temp eratur es are ver y high along the I-95 corridor and slightl y cooler

furtherinland. Winds are more consistentl y south - southwest at all sites than under other

episode t yp es and almost no northwest-north-northeast winds are seen at LaGuardia in contrast to other t yp es. Resultant wind vector magnitud es are much higherThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

than average, consistent with the steady southwest flow. Southwest – northeast pres sure gradients along the I-95 corridor and from Pittsburgh to Buffalo are positive, consistent with the southwest flow. Average east-west pressure gradients are near zero. These conditions result in above average ozone levels all along the I-95 corridor with advection north into coastal and interior Ne w England. Ozone levels are slightl y below average in the extrem e southeastern and western OTR.
“Type D”

– High o zone in the western O TR . This pattern is character ized by an area of

me an upper level divergence with associated cut- off low at 850 mb off the Outer Bank s of North Carolina. A relative l y vigorous me an low pressure center can be seen at the surface. A n east- we st temper ature gradientacross the OTR is evident at 850 mb. Surface te mpera tures along the I-95 corridor and in Alban y are below average but s urface te mpera ture is above average at Buffalo. The 850 mb heights are the highest of an y episode ty

pe due to a strong ridge over New England. S urface winds are mostl y eastnortheast along the I-95 corridor from DC to New Y ork but more variable further north. In contrast to episode ty

pe s A, B, or C, the southwest-northeast pressure gradients along the I-95 corridor are negative, consistent with the northeast surface winds. West- east pressure gradients are flat. These conditions result in below average ozone in the eastern OTR due to the on-shore flow in the north and cy cl on ic conditions in the south but above average ozone levels in the w estern OTR due to stable, warm conditions with light wind s.
“Type E”

– Generally low ozone throughout the OTR . This categor y includes da ys with moder ate l y low to lowest average ozone readings of all OTR exceedance da ys used in the character iza tion schem e. The Bermuda high is shifted east relative to the other t yp es and flow over the southeastern U. S. is onl y weakly anti- c yc lon ic with a nearl y zonal flow pattern at the 850 and 500 mb levels over the OTR. Temp eratures at the s urface and aloft

are the coolest

of an y episode ty

pe

. While wind s aloft are nearl y we sterl y , surface wind s
are generall y south-southeast over most of the OTR. The southwest-northeast pressure gradients are negative along the I-95 corridor and east- w est gradients are po sitive, consistent with the southeast flow. These conditions result in below average ozone throughout the OTR due to the relativel y low temper atures and s outheasterl y on shore flow at coastal locations.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

Figur e B- 1. Avera ge 850 mb height and wind fields for each episode (pattern) t yp e identified b y Stoeckenius and Kemball- C ook (pattern numbers refer t o the episode ty

pe s li sted i n tex t): Pattern 1 = Episode T yp e E, 2 = B, 3 = A, 4 = D, 5 = C) (Figur e 3- 2 of S toeckenius & Kemball- C ook (2005)).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

Figur e B- 2. Avera ge surface temperature and 10 m wind fields for each episode (pattern) t yp e i dentified by Stoeckenius and Kemball- C ook (pattern numbers refer t o the episode ty

pe s li sted i n tex t): Pattern 1 = Episode T yp e E, 2 = B, 3 = A, 4 = D, 5 = C) (Figur e 3- 5 of S toeckenius & Kemball- C ook (2005)).The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



# Appendix C: Exceedance days by m onito r

i n the OTRThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2



## Appendi x C: E xceedance days by moni tor in the OTR
Tables of the number

of 8-hour ozone N AA QS exceedance day s recorded at individual monitors in the OTR nonattain me nt /at tain me nt

areas for the 1997-2005 ozone season s. Hourly data were downloaded in Januar y 2006 from the USEP A Air Qualit y S ys tem ( AQS) database. The number

of 8-hour ozone exceedance day s were calculat ed using procedures specified in U SEPA’s “ G uideline on Data Handling Conventions for the 8-hour Ozone NA AQS” ( OAQP S, EPA-454/R-98-017, Dec. 1998) with flagged data (due to a regional forest fire smoke event) eli min ated from the analy si s. While these tables are derived from the publicl y availabl e data in the U SEPA AQ S database, states ma y have monitor ing data that differfrom these. For exa mple, the tables contain state- specific data provided by the Mary la nd Depart ment of the Environ ment and the Ne w Jersey Depart ment of Environmen tal Protection that differfrom the USEP A AQS database at the time the data were do wnloaded in Januar y 2006. “ ***” indicates y ea rs during which a mon itor was not in operation or had less than 75 percent data collection during the ozone season.

Philadelp hia- W i l mi ngton- Atlantic City, PA- NJ -MD -DE ( Classi fication: MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
100 01 00 02 Kent Kil lens Pond DE 14 17 13 5 8 10 3 0 2 100 03 10 03 New Castle Bellefonte DE 6 8 10 5 5 11 *** *** *** 100 03 10 07 New Castle Lums Pond DE 15 12 12 5 9 9 4 0 6 100 03 10 10 New Castle Brandy wi ne Creek DE 17 17 16 7 15 18 3 3 3 100 03 10 13 New Castle W i l m ington (Belle font e2) DE *** *** *** *** *** 8 3 1 4 100 05 10 02 Sussex Seaford DE 14 16 17 5 4 10 4 0 3 100 05 10 03 Sussex Lew es DE *** 17 17 6 10 14 4 2 7 240 15 00 03 Cecil Fairhil l MD 19 20 20 18 16 17 6 3 9 340 01 00 05 Atlantic Nacote C reek NJ 18 24 14 4 9 11 4 0 3 340 07 00 03 Camden Camden Lab NJ 12 15 16 6 19 19 4 3 5 340 07 10 01 Camden Ancora NJ 23 29 25 10 17 27 9 6 12 340 11 00 07 Cumberland M ill vi lle NJ 14 17 17 6 14 20 6 2 4 340 15 00 02 Gloucest er C larksboro NJ 19 22 21 8 17 24 6 4 6 340 21 00 05 Mercer R ider Univ

. NJ 16 17 24 11 15 26 7 1 7 340 29 00 06 Ocean Coll iers M ills NJ 21 28 23 11 21 30 9 8 14 420 17 00 12 Bucks Bristol PA 14 17 24 14 16 17 9 2 7 420 29 00 50 Chester W e st Chester PA *** *** *** *** 20 19 4 *** ***The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

Philadelp hia- W i l mi ngton- Atlantic City, PA- NJ -MD -DE ( Classi fication: MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 29 01 00 Chester New Garden PA *** *** *** *** 17 23 4 5 8 420 45 00 02 Delaware Chester PA 19 17 19 7 12 16 3 2 4 420 91 00 13 Montgomer y Nor ristow n PA 19 17 20 11 18 12 4 1 8
421 01 00 04 Philadelp hia Philadelp hia - Downt ow n PA 0 1 2 1 0 0 2 0 0 421 01 00 14 Philadelp hia Philadelp hia - Ro xborou gh PA 10 7 *** 4 10 13 2 0 3
421 01 00 24 Philadelp hia Philadelp hia - NE Airport PA 17 15 *** 5 13 22 4 6 8
421 01 01 36 Philadelp hia Philadelp hia - Elmwood PA 0 4 12 3 5 13 2 0 ***

Baltimore, MD ( Classif ication : MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
240 03 00 14 Anne Arundel Da vidsonville MD 20 42 31 7 14 25 5 4 9 240 03 00 19 Anne Arundel Fort Meade MD 24 25 27 10 19 20 3 5 *** 240 05 10 07 Baltimore Pado nia MD 10 7 14 3 9 19 2 1 2 240 05 30 01 Baltimore Essex MD 10 11 11 3 10 14 3 2 6 240 13 00 01 Car roll South Carroll MD 9 18 16 5 10 10 2 1 5 240 25 10 01 Har ford Edge wo od MD 18 17 17 11 20 25 7 6 11 240 25 90 01 Har ford Aldino MD 20 12 17 8 18 22 4 3 10 245 10 00 53 Baltimore ( City) Baltimore-Ponc a St MD *** *** *** *** *** 8 *** *** *** 245 10 00 50 Baltimore ( City) Baltimore-005 0 MD 16 *** *** *** *** *** *** *** ***
245 10 00 51 Baltimore ( City) Baltimore-005 1 MD 9 5 7 *** *** *** *** *** ***

New York- N. New Jersey- Lon g Island
, NY- NJ -CT (C lassification: MO DERATE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
900 10 01 7 Fair field Greenwic h CT 13 8 14 3 13 18 7 1 8 900 11 12 3 Fair field Danbur y CT 14 9 17 7 9 17 4 4 11 900 13 00 7 Fair field Stratford CT 17 11 9 4 10 20 8 2 8 900 19 00 3 Fair field W e stport CT 15 13 13 3 15 19 6 2 10The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

New York- N. New Jersey- Lon g Island
, NY- NJ -CT (C lassification: MO DERATE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
900 10 11 3 Fair field Bridgep ort CT 6 *** *** *** *** *** *** *** *** 900 70 00 7 M iddlesex M iddlet ow n CT 12 5 15 6 11 16 7 1 7 900 91 12 3 & 900 90 02 7 New Haven New Haven CT 7 3 5 *** *** *** *** 1 2

900 93 00 2 New Haven Madison CT 19 9 16 6 11 19 9 2 8 900 99 00 5 New Haven Hamden CT *** *** 11 2 9 14 7 *** *** 340 03 00 05 Bergen T eaneck NJ *** *** *** 2 10 18 4 2 8 340 03 00 01 Bergen C lif fs ide Park NJ 5 *** *** *** *** *** *** *** ***
340 13 00 11 & 340 13 00 16 Essex Newark Lab NJ 6 5 6 *** *** 6 *** *** ***

340 17 00 06 Hudson Bay on ne NJ 9 7 17 3 6 6 2 1 6 340 19 00 01 Hunterdo n F lemingt on NJ 18 21 23 9 12 19 7 6 13 340 23 00 11 M iddlesex Rutgers Univ

. NJ 16 15 23 10 17 26 5 2 10 340 25 00 05 Monmouth Monmouth Univ

. NJ 12 20 12 5 8 17 10 2 8 340 27 30 01 Mor ris Chester NJ 13 22 21 6 15 27 5 0 3 340 31 50 01 Passaic Ramapo NJ *** 8 16 1 9 13 2 2 8 340 39 00 08 Union Plainfield NJ 5 *** *** *** *** *** *** *** *** 360 05 00 80 Bronx NYC-Morrisania Center NY 5 1 5 *** *** *** *** *** ***

360 05 00 83 Bronx NYC-200 t h St & Sout hern Bl vd NY 5 0 8 1 1 6 2 1 0

360 05 01 10 Bronx NYC-IS52 NY *** *** *** 1 *** 6 2 0 1 360 61 00 10 New York NYC-Mabel Dean HS NY *** 2 3 0 *** *** *** *** *** 360 61 00 63 New York NYC-Roof W T C NY 16 22 18 5 12 *** *** *** *** 360 81 00 04 Quee ns NYC-Que ens College NY 10 *** *** *** *** *** *** *** *** 360 81 00 97 Quee ns NYC-QBORO NY *** *** 10 3 3 *** *** *** *** 360 81 00 98 Quee ns NYC-College Pt NY *** *** *** 1 1 1 1 0 0 360 81 01 24 Quee ns NYC-Que ens NY *** *** *** *** *** 7 4 0 4 360 85 00 67 R ichmond NYC-Susa n W ag ner HS NY 21 12 17 11 10 19 5 2 8 361 03 00 02 Suf folk Babyl on NY 8 10 11 4 2 9 6 2 6 361 03 00 04 Suf folk R ive rhea d NY 11 9 16 4 3 6 3 *** 6 361 03 00 09 Suf folk Holts vil le NY *** *** *** 4 8 18 6 2 ***The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

New York- N. New Jersey- Lon g Island
, NY- NJ -CT (C lassification: MO DERATE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
361 19 20 04 W e st chester W h it e Plains NY 11 6 12 2 8 15 4 0 9

W a sh ingto n, D C-M D-VA ( Classif ication : MODERATE )
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
110 01 00 25 D istrict of Columbia (al l) T akoma D C 11 18 15 5 7 13 3 2 1 110 01 00 41 D istrict of Columbia (al l) R ive r T er race D C 12 11 16 2 7 12 2 0 1 110 01 00 43 D istrict of Columbia (al l) M cMil lian Reservoir D C 18 20 22 2 12 21 3 3 5 240 09 00 10 & 240 09 00 11 Cal vert Cal vert MD 4 10 10 5 5 *** *** *** 2

240 17 00 10 Charles S. Ma ryla nd MD 17 30 31 5 9 15 6 1 6 240 21 00 37 F rederick F rederick Municipal Ai rport MD *** *** 19 4 14 13 3 1 1 240 31 30 01 Montgomer y Rock vil le MD 13 22 16 2 11 11 3 2 3 240 33 00 02 Prince George's Greenb elt MD 24 24 23 7 19 15 3 *** *** 240 33 80 01 Prince George's Suitland MD 14 25 18 3 14 *** *** *** *** 240 33 80 03 Prince George's Equestria n Center MD *** *** *** *** *** 15 4 5 5 510 13 00 20 Arl ingt on Co Aurora Hi lls VA 17 10 21 3 12 18 4 4 5 510 59 00 05 Fair fax Chantilly ( Cub Run) VA 2 16 6 2 9 12 2 3 0 510 59 00 18 Fair fax Mount Verno n VA *** 17 16 4 10 16 5 6 8 510 59 00 30 Fair fax F ranco nia VA *** *** 19 0 14 18 5 5 6
510 59 10 04 & 510 59 10 05 Fair fax Seven Corners & Anna nd ale VA 10 17 9 2 *** 20 3 4 4

510 59 50 01 Fair fax M cLea n – Le winsville VA 3 7 6 2 8 7 3 3 2 511 07 10 05 Loud ou n Ashburn VA *** 17 7 1 9 23 3 2 *** 511 53 00 09 Prince W i l li am James S. Long Park VA 4 13 9 2 6 7 4 1 0
515 10 00 09 Ale xandria (C ity) Ale xandria VA 5 10 10 2 6 10 3 3 2

Jef ferson Co., NY ( Classi fication: MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6

360 45 00 02 Jef ferson Perch Ri ver NY 8 4 6 1 17 13 9 2 3

Greater Conn ecticut
, CT (C lassification: MO DERATE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
900 31 00 3 Hart ford East Hartford CT 7 2 11 2 8 10 0 1 5 900 50 00 5 Litchfield Cornwall (Mohawk Mt) CT *** *** *** *** *** 13 4 2 8 900 50 00 6 Litchfield T or ringto n CT 9 10 12 4 *** *** *** *** *** 901 10 00 8 New Lon do n Groton CT 17 3 11 3 7 7 5 1 4
901 31 00 1 T olland Staf ford CT 10 8 12 1 10 13 1 2 8

Bosto n- Lawre nce- W o r cester (E. MA), MA (Classi fication: MO DERATE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
250 01 00 02 Barnsta ble T ru ro MA 17 2 12 3 13 9 8 3 7 250 05 10 02 Bristol Fairhaven MA 12 2 8 3 8 5 8 1 1 250 05 10 05 Bristol Easton MA 7 7 3 0 14 *** *** *** ***

250 07 00 01 Dukes W a m panoa g Labora tor y

– Martha’s Viney ard MA *** *** *** *** *** *** *** 0 4

250 09 50 05 Essex Lawre nce- Haverhill MA 2 1 1 0 0 6 *** *** 0 250 09 20 06 Essex Lyn n MA 6 7 6 1 11 13 3 2 6 250 09 40 04 Essex Newbur y MA 6 6 6 0 8 9 2 1 0

250 17 00 09 M iddlesex USEPA Region 1 Lab – Chelms ford MA *** *** *** *** *** *** *** *** 2

250 17 11 02 M iddlesex Stow MA *** 5 8 1 12 8 0 1 2 250 17 18 01 M iddlesex Sudb ury MA 6 4 *** *** *** *** *** *** *** 250 17 40 03 M iddlesex W a lt ham MA 6 7 5 *** *** *** *** *** *** 250 21 30 03 Nor folk E Milton (Blue Hi ll) MA *** *** *** *** *** 17 5 2 4 250 25 00 41 Suf folk Boston- Long Island MA *** *** 4 0 9 10 1 1 5 250 25 00 42 Suf folk Boston- Ro xbury MA *** *** 0 0 2 2 1 1 1 250 25 10 03 Suf folk Chelsea MA 2 4 3 *** *** *** *** *** ***
250 27 00 15 W o r cester W o r cester MA 5 6 8 1 6 *** 1 0 5The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 7

Pro videnc e (All RI), RI (Classi fication: MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
440 03 00 02 Kent W G reen wich RI 10 4 7 5 13 12 1 2 5 440 07 10 10 Pro videnc e E Providence RI 3 2 2 2 10 9 4 2 4
440 09 00 07 W a sh ingto n Nar raga nse tt RI *** 1 11 4 11 8 8 4 5

Springfield ( W e stern MA), MA ( Classi fication: MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
250 03 40 02 Berkshire Adams MA *** *** 1 *** 16 4 2 1 6 230 13 00 03 Hampden Agaw am MA 9 1 1 1 2 6 *** *** *** 250 13 00 08 Hampden Chicopee MA 7 5 7 1 9 10 3 1 8 250 15 01 03 Hampshire South Hadle y (Amherst) MA 2 2 3 1 3 4 0 1 1
250 15 40 02 Hampshire W a r e MA 9 6 9 2 12 10 0 3 8

Poug hke epsie
, NY ( Classi fication: MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
360 27 00 07 Dutchess M illbrook NY 7 8 8 2 8 8 0 1 3 360 71 50 01 Orange Valley Central NY 6 6 8 1 12 4 4 2 7
360 79 00 05 Putnam Mt N inham NY 7 8 15 1 10 19 2 1 7

Bosto n- Manchest er- Portsmouth (SE), N H (Classi fication: MODERA TE)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
330 11 00 16 & 330 11 00 19 & 330 11 00 20 H illsboroug h Manchest er N H 3 0 *** 0 *** 4 0 1 0

330 11 10 10 & 330 11 10 11 H illsboroug h Nashua N H 4 3 8 1 7 5 1 2 1The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 8

330 15 00 09 & 330 15 00 15 & 330 15 00 14 Rockingham Portsmouth N H 5 3 5 0 *** 8 0 1 0

330 15 00 13 Rockingham Brentw oo d N H *** 0 1 0 4 10 *** *** ***
330 15 00 12 & 330 15 00 16 Rockingham Rye N H 9 4 3 0 7 7 0 1 0

330 17 30 02 Straf ford Rochester N H 1 0 2 0 1 6 0 *** ***

Kent and Quee n Ann e’s Cos., MD ( Classif ication : MARGINAL)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
240 29 00 02 Kent M ill ingt on MD 19 16 22 6 13 17 4 1 3

Lancas ter, PA ( Classi fication: MARGINAL)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 71 00 07 Lancas ter Lancas ter PA 21 27 18 5 15 18 3 1 6The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 9

Portland
, ME ( Classi fication: MARGINAL)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
230 05 00 27 Cumberland Portland ME *** *** *** *** *** *** *** 0 0 230 05 20 03 Cumberland Cape Eliza bet h ME 6 5 2 0 8 5 0 0 0
230 23 00 03 & 230 23 00 04 Saga da hoc Phippsb urg/ Ge orget ow n ( Reid Stat e Park) ME 7 4 4 1 *** 5 1 0 0

230 31 30 02 York Kittery ME 7 4 4 0 4 12 2 1 0 230 31 20 02 York Kenn eb unk port ME 5 5 5 1 8 10 2 1 0
230 31 00 37 & 230 31 00 38 York Holl is ME 2 0 1 0 *** 3 0 0 0

Buffalo-Niagara Falls, NY (C lassification: SUBPAR T 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
360 29 00 02 Erie Amherst NY 0 13 6 4 10 21 7 0 5
360 63 10 06 N iagara M iddlep ort NY 1 6 7 3 10 16 6 0 4

Yo un gsto wn- W a r ren-Sharon
, OH-PA ( Classif ication : SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
390 99 00 09 & 390 99 00 13 Mahonin g Yo un gsto wn - Oakhill OH 3 15 7 1 5 14 4 1 2

391 55 00 08 & 391 55 00 11 T ru mbull W a r ren-T ru mbull Count y OH 8 19 10 2 12 24 5 2 5

391 55 00 09 T ru mbull Kinsman OH 7 15 10 2 5 16 4 0 2
420 85 01 00 Mercer Far rell PA 9 24 8 2 15 20 6 1 4The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 10

Pittsburg h- Beaver Valle y, PA ( Classi fication: SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5

420 03 00 08 Alleghe ny Lawre nceville PA 7 14 10 3 4 16 5 0 1

420 03 00 10 Alleghe ny Pittsburg PA *** 6 16 4 9 25 5 0 4 420 03 00 67 Alleghe ny South Faye tte PA 8 24 15 4 7 17 4 1 4 420 03 00 88 Alleghe ny Penn H ills PA 5 16 11 4 *** *** *** *** *** 420 03 10 05 Alleghe ny Har rison Township PA 12 18 14 4 8 14 2 0 6 420 05 00 01 Ar mstrong Kittanni ng PA *** 21 18 2 16 15 5 1 4 420 07 00 02 Beaver Hookstow n PA 4 11 9 1 9 19 6 0 5 420 07 00 05 Beaver Brighton Township PA 3 15 11 1 8 23 3 0 4 420 07 00 14 Beaver Beaver Fal ls PA 5 10 6 3 4 9 3 0 2
421 25 00 05 W a sh ingto n Charleroi PA 14 34 11 3 7 14 4 0 2 421 25 02 00 W a sh ingto n W a sh ingto n PA 6 15 11 3 6 9 5 0 4
421 25 50 01 W a sh ingto n F lorenc e PA 4 11 9 2 7 17 3 0 4 421 29 00 06 W e st moreland Mur rysville PA 4 3 5 2 1 9 2 0 4
421 29 00 08 W e st moreland Greensb urg PA *** *** 16 3 3 10 4 0 2

Jamestow n, NY (C lassification: SUBPAR T 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
360 13 00 06 Chauta uq ua Dunkirk NY *** *** 12 5 11 23 7 4 6
360 13 00 11 Chauta uq ua W e st fie ld NY 4 11 8 3 4 18 4 0 2The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 11

Hancock, Knox, Lincoln & W a l do Cos., ME ( Classif ication : SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
230 13 00 04 Knox Port C lyd e ME 6 3 2 0 6 5 3 0 1 230 09 04 01 Hancock Schoo dic Point ME *** *** *** *** *** *** 1 0 *** 230 09 00 01 Hancock Seaw all ME *** *** *** 0 4 *** *** *** ***
230 09 01 01 & 230 09 01 03 Hancock Acadia National Park – M cFarland H ill ME 1 4 5 0 9 6 2 0 0

230 09 01 02 Hancock Acadia National Park – Cadillac M tn. ME 5 8 4 3 9 8 3 0 3

F ranklin Co., PA (Classi fication: SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 55 00 01 F ranklin Methodist H ill PA 7 22 20 4 15 27 3 0 0

Erie, PA ( Classif ication : SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 49 00 03 Erie Erie PA 6 12 13 2 4 17 4 0 4

Essex Co. ( W hi teface Mtn.), NY ( Classif ication : SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
360 31 00 02

360 31 00 03 Essex ( W hi teface Mountain above 1,9 00 foot ele vation ) W h it eface Mountain Summit NY 2 1 3 2 5 12 7 0 ***

W h it eface Mtn. Base NY 1 2 3 0 3 11 5 0 1The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 12

Allento wn- Bethle hem- Easto n, PA (Classi fication: SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 77 00 04 Lehig h Allentow n PA 12 18 19 5 9 16 4 3 6 420 95 00 25 Northampto n F reemans bur g PA 0 5 22 6 14 12 4 6 5
420 95 01 00 & 420 95 80 00 Northampto n Easton PA 11 8 12 2 11 13 3 1 1

Readin g, PA ( Classi fication: SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 11 00 01 Berks Kutz to wn PA 6 14 12 2 7 11 1 *** ***
420 11 00 09 & 420 11 00 10 Berks Reading PA 10 16 14 3 8 13 3 1 4

C learfield and Indian a Cos., PA (Classi fication: SUBPAR T 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 63 00 04 Indian a Strongst ow n PA *** *** *** *** *** *** *** *** 5
420 33 40 00 C learfield Moshann on PA 12 16 1 2 8 13 4 0 4

Green e Co., PA (Classi fication: SUBPAR T 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 59 00 02 Greene Holbrook PA *** *** 21 6 12 9 3 0 5

York, PA ( Classi fication: SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ysThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 13

1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 01 00 02 Adams Bigler ville PA *** *** *** *** *** 7 2 0 1
421 33 00 08 York York PA 13 18 10 6 8 12 3 1 6

Rochester, NY (C lassification: SUBPAR T 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
360 55 10 04 & 360 55 10 07 Monroe Rochester NY 4 1 *** 1 3 12 3 0 0

361 17 30 01 W a yne W i l li am son NY 4 4 7 1 5 10 2 0 0

Albany

- Schen ect ad y- Tr oy, NY (C lassification: SUBPAR T 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
360 01 00 12 Albany Albany – Lou do nville NY 2 1 3 1 6 6 2 2 3 360 83 00 04 Rensselaer Gra fton State Park NY *** *** *** *** *** 16 2 2 2 360 91 00 04 Sarato ga Stillwater NY 3 2 6 1 7 6 5 2 3
360 93 00 03 & 360 93 00 93 Schen ecta dy Schen ecta dy NY 1 0 2 1 1 3 2 0 0

Har risburg- Leba no n- Carlis le, PA (C lassification: SUBPAR T 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 43 04 01 Dauphin Har risburg PA 3 22 15 3 7 11 2 1 3 420 43 11 00 Dauphin Hershey PA 9 9 15 5 12 13 2 0 4
420 99 03 01 Perry Little Buffalo Stat e Park PA 7 8 13 2 10 7 3 0 1

Johnst ow n, PA ( Classi fication: SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 21 00 11 Cambria Johnst ow n PA 7 13 11 5 5 6 2 0 1The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 14

Scranto n- W i l ke s-Barre, PA ( Classif ication : SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 69 01 01 Lackaw an na Peckv ille PA 6 5 11 1 5 14 2 0 2 420 69 20 06 Lackaw an na Scranto n PA 4 5 11 1 5 8 2 0 1 420 79 11 00 Luz erne Nanticoke PA 0 2 4 1 5 6 3 0 0 420 79 11 01 Luz erne W i l ke s-Barre PA 8 7 9 1 7 7 2 0 1

State College, PA ( Classi fication: SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 27 01 00 Centre State College PA *** *** *** 2 5 8 3 0 1
420 27 40 00 Centre Penn Nursery PA 7 8 4 2 1 12 4 0 ***

T ioga Co., PA (C lassif ication : SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
421 17 40 00 T ioga T ioga PA *** *** *** 2 3 8 3 0 0

Altoo na, PA (C lassif ication : SUBPART 1)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 13 08 01 Blair Altoon a PA 7 17 6 2 3 9 3 0 1

W a sh ingto n Co. (Hagersto wn), MD ( Classi fication: SUBPART 1 EARLY ACT ION CO MPACT )
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
240 43 00 09 W a sh ingto n Hagerstow n MD *** *** 11 2 5 17 3 1 2The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 15

New York

(C lassification: A TT AINMEN T)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
360 15 00 03 Gloucest er Elm ira NY 0 2 2 1 2 4 1 0 0 360 41 00 05 Ham ilton Piseco Lake NY 1 1 1 1 2 4 2 0 1 360 43 00 05 Herk imer N icks Lake NY 0 0 0 1 0 1 2 0 0 360 53 00 06 Madison Camp Georg et ow n NY 0 2 1 1 2 5 2 0 0 360 65 00 04 Oneida Camden NY 0 1 1 1 3 5 2 0 0 360 67 10 15 Onon da ga East Syrac use NY 2 3 4 1 4 9 2 0 2 360 75 00 03 Osweg o Fulton NY *** *** *** *** *** *** 5 0 2
361 11 10 05 U lster Belleayr e Mountain NY 4 1 3 1 3 1 3 0 0

Maine ( Classif ication : AT TAIN MENT )
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
230 11 20 05 Kenn eb ec Gardiner ME 2 3 1 0 3 4 1 0 0 230 09 03 01 Hancock Castine ME *** *** *** *** *** 3 1 0 0 230 21 00 03 Piscataq uis Do ver-Fo xcroft ME *** 0 1 0 0 *** *** *** *** 230 19 40 08 Peno bscot Holden ME 0 2 0 *** 6 4 1 0 0 230 17 30 01 O xfo rd North Lovell ME 0 0 0 0 0 1 0 0 0 CC0040 00 2 NB CAN Roosevelt-Campob ello IP NB 0 1 0 0 0 0 0 0 0 230 19 40 07 Peno bscot Howlan d ME 0 0 1 0 0 1 0 0 0
230 03 80 01 Aroosto ok Ashland ME 0 0 0 0 0 1 0 0 0The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 16

Penns ylvania ( Classif ication : AT TAIN MENT )
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
420 73 00 15 Lawre nce New Castle PA 4 2 5 0 1 6 2 0 1 420 81 01 00 Lycomin g Montoursville PA *** *** *** *** *** 7 3 0 3 420 81 04 03 Lycomin g W i l li am sport PA 0 1 0 1 1 *** *** *** ***
420 81 40 00 Lycomin g T iadagh to n PA 0 3 0 1 1 3 2 0 ***

Vermont ( Classif ication : AT TAIN MENT ) AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
500 03 00 04 Bennin gt on Bennin gt on V T 2 0 3 1 2 4 0 2 0
500 07 00 07 Chittend en Underhill V T 0 0 1 0 0 3 0 0 0

New Hampshire (C lassification: A TT AINMEN T)
AQS MONIT OR ID COU NTY MO NITOR NAME S T 8-hr Ozone exc eed anc e da ys 1997 1998 1999 2000 2001 2002 2003 2004 200 5
330 01 20 03 & 330 01 20 04 Belknap Laconi a N H 1 0 0 *** 2 3 0 0 0

330 03 10 02 Car roll Conwa y N H 0 0 0 0 0 1 *** *** *** 330 05 00 07 Cheshire Keen e N H 1 1 1 1 1 1 0 0 0 330 07 40 02 Coos Mt W a sh ingto n Base N H *** *** *** *** *** 0 0 1 0 330 07 40 03 Coos Pittsburg N H *** *** *** *** *** *** 0 0 0
330 09 00 08 & 330 09 20 05 Gra fton Ha verhill-Leba no n N H 0 0 0 0 0 1 0 0 0

330 11 50 01 H illsboroug h Peterb orou gh ( Miller State Park) N H *** *** *** *** *** *** 0 1 3

330 17 00 07 & 330 17 10 07 Straf ford Concord N H 1 0 0 0 1 4 0 1 0

330 19 00 03 Sulli van C laremont N H 1 0 0 1 0 3 0 1 0The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 17



# Appendix D: 8 -hour o zone des ign values i n the OTR, 1997-2005DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 18



## Appendi x D: 8-hour o z one des ign values in the OTR, 1997-2005
Tables of the valid 8-hour ozone design values (3-ye ar averages of the ozone season 4 th maxi mu m 8-hour ozone concentrations) recorded at individual moni tors in OTR nonattain me nt/ att ainm en t areas for the 1997-2005 ozone season s. Hourl y data were downloaded from the U SEPA Air Qualit y Sy ste m (A QS) database in J anuar y 2006. The 8-hour averages and design values were calcula ted u sing procedures specified in EPA’s “ Guideline on Data Handling Conventions for the 8-hour Ozone N AAQ S” ( OAQP S, EPA-454/R-98-017, Dec. 1998) with flagged data (due to a regional fore st fire smoke event) eli mi nated from the anal ys is. “***” indicat es ye ars during which a monitor wa s not in operation or had less than 90 percent data collection ( with a design value less than 85 ppb) for the respective 3-y ea r period. Red s hading indicates averages ≥ 85 ppb (violating the 8-hr ozone NA AQS), orange shading indicat es averages between 80 and 84 ppb, y el low shading indicates average between 75 and 79 ppb and green shading indicates averages < 75 ppb. While these tables are derived from the publicl y available data downloadedin Januar y 2006 from the USEPA A QS database, states ma y have monitor ing data that differfrom these. For examp le, de sign values for New Jer se y were provided b y the New Jer se y Departmen t of Environ menta l Protection and differ in s ome instances from the derived values based on the U SEPA A QS database.

Philad elphi a- W i l m ington- Atlantic C ity, PA-NJ-M D-DE (C lassification: M ODERATE ) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 100 01 00 02 Kent Kil lens Pond DE 99 97 93 92 89 84 80 100 03 10 03 New Castle Bellefonte DE 90 91 91 92 *** *** *** 100 03 10 07 New Castle Lums Pond DE 100 97 97 96 93 84 80 100 03 10 10 New Castle Brandy wi ne Creek DE 99 96 95 96 93 89 82 100 03 10 13 New Castle W i l m ington (Belle font e2) DE *** *** *** *** 90 85 82 100 05 10 02 Sussex Seaford DE 99 98 95 94 91 85 82 100 05 10 03 Sussex Lew es DE *** 95 90 87 88 85 84 240 15 00 03 Cecil Fairhil l M D 110 106 106 104 98 91 89 340 01 00 05 Atlantic Nacote C reek NJ 101 94 95 91 91 8 5 82 340 07 00 03 Camden Camden Lab NJ 104 101 104 101 102 93 85 340 07 10 01 Camden Ancora NJ 111 106 108 104 102 96 92 340 11 00 07 Cumberlan d M ill vi lle NJ 104 101 102 98 98 91 86 340 15 00 02 Glouces ter C larksboro NJ 106 105 105 104 100 94 88 340 21 00 05 Mercer R ider Univ

. NJ 112 109 112 102 99 91 85DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 19

Philad elphi a- W i l m ington- Atlantic C ity, PA-NJ-M D-DE (C lassification: M ODERATE ) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 340 29 00 06 Ocea n Coll iers M ills NJ 113 114 115 113 109 99 94 420 17 00 12 Bucks Bristol PA 103 102 105 104 100 93 86 420 29 00 50 Chester W e st Chester PA *** *** *** *** 95 *** *** 420 29 01 00 Chester New Garden PA *** *** *** 95 98 91 87 420 45 00 02 Delaw are Chester PA 100 96 94 95 92 88 82 420 91 00 13 Montg omery Nor ristow n PA 104 102 100 97 92 88 86 421 01 00 04 Philad elphi a Philadelp hia – Downto wn PA 72 72 71 74 75 68 63
421 01 00 14 Philad elphi a Philadelp hia – Ro xborou gh PA 90 87 88 93 93 86 81 421 01 00 24 Philad elphi a Philadelp hia – NE Airport PA *** *** *** 98 97 95 90
421 01 01 36 Philad elphi a Philadelp hia – El mwo od PA 86 89 88 87 84 80 ***

Baltimore, M D (Classi fication: MO DERATE) 8-hr Ozon e DESIGN VALUE (ppb) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 240 03 00 14 Ann e Arund el Da vidsonville M D 109 107 103 102 98 94 89 240 03 00 19 Ann e Arund el Fort Meade M D 107 100 100 101 97 93 *** 240 05 10 07 Baltimore Pado nia M D 95 92 93 92 89 85 77 240 05 30 01 Baltimore Essex M D 99 93 93 93 93 88 83 240 13 00 01 Carroll South Carroll M D 95 94 93 92 89 85 82 240 25 10 01 Harford Edge wo od M D 105 100 104 104 103 94 91 240 25 90 01 Harford Aldino M D 106 97 98 100 98 93 86 245 10 00 53 Baltimore (City) Baltimore-Ponc a St M D *** *** *** *** *** *** *** 245 10 00 50 Baltimore (City) Baltimore-005 0 M D *** *** *** *** *** *** ***
245 10 00 51 Baltimore (City) Baltimore-005 1 M D 90 *** *** *** *** *** ***

New York- N. New Jersey- Long Island, NY- N J-C T ( Classi fication: MODERA TE) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 900 10 01 7 Fairf ield Greenwic h C T 99 93 96 95 100 92 87 900 11 12 3 Fairf ield Danbur y C T 101 96 97 98 96 93 91 900 13 00 7 Fairf ield Stratford C T 98 94 96 98 102 95 90DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 20

New York- N. New Jersey- Long Island, NY- N J-C T ( Classi fication: MODERA TE) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 900 19 00 3 Fairf ield W e stport C T 103 94 97 93 97 92 89 900 10 11 3 Fairf ield Bridgep ort C T *** *** *** *** *** *** *** 900 70 00 7 Middlesex M iddlet ow n C T 99 95 99 97 98 92 90
900 91 12 3 & 900 90 02 7 New Ha ven New Haven C T 86 *** *** *** *** *** ***

900 93 00 2 New Ha ven Madison C T 103 96 97 98 102 95 90 900 99 00 5 New Ha ven Hamden C T *** *** 95 94 98 *** *** 340 03 00 05 Berge n T eaneck NJ *** *** *** 92 95 89 86 340 03 00 01 Berge n C lif fs ide Park NJ *** *** *** *** *** *** ***
340 13 00 11 & 340 13 00 16 Essex Newark Lab NJ 93 *** *** *** *** *** ***

340 17 00 06 Hudso n Bay on ne NJ 107 99 100 86 87 82 84 340 19 00 01 Hunterd on F lemingt on NJ 106 103 104 97 97 92 90 340 23 00 11 Middlesex Rutgers Univ

. NJ 113 109 111 101 98 89 86 340 25 00 05 Monmout h Monmouth Univ

. NJ 100 102 101 97 97 93 89 340 27 30 01 Morris Chester NJ 102 100 101 98 98 90 82 340 31 50 01 Passaic Ramapo NJ *** 89 94 88 88 84 81 340 39 00 08 Union Plainfield NJ *** *** *** *** *** *** *** 360 05 00 80 Bronx NYC-Morrisania Center NY 84 *** *** *** *** *** *** 360 05 00 83 Bronx NYC-200 t h St & Sout hern Bl vd NY 88 80 83 81 84 83 75 360 05 01 10 Bronx NYC-IS52 NY *** *** *** *** *** 80 76 360 61 00 10 New York NYC-Mabel Dean HS NY *** 69 *** *** *** *** *** 360 61 00 63 New York NYC-Roof W T C NY 106 98 98 *** *** *** *** 360 81 00 04 Que ens NYC-Que ens College NY *** *** *** *** *** *** *** 360 81 00 97 Que ens NYC-QBORO NY *** 88 86 *** *** *** *** 360 81 00 98 Que ens NYC-College Pt NY *** *** 68 74 75 72 69 360 81 01 24 Que ens NYC-Que ens NY *** *** *** *** *** *** *** 360 85 00 67 Richmond NYC-Susa n W ag ner HS NY 105 96 98 96 94 89 87 361 03 00 02 Suffolk Babyl on NY 97 91 87 92 95 94 91 361 03 00 04 Suffolk R ive rhea d NY 98 94 91 85 *** *** *** 361 03 00 09 Suffolk Holts vil le NY *** *** *** 97 100 94 ***DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 21

New York- N. New Jersey- Long Island, NY- N J-C T ( Classi fication: MODERA TE) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 361 19 20 04 W es tchester W h it e Plains NY 98 92 92 90 94 90 88

W a sh ingto n, D C-M D-VA ( Classif ication : MODERATE ) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005
110 01 00 25 Distr ict of Columbia (all) T akoma DC 95 96 93 93 88 85 78

110 01 00 41 Distr ict of Columbia (all) R ive r T er race DC 91 88 88 91 92 84 77

110 01 00 43 Distr ict of Columbia (all) M cMil lian Reservoir DC 100 96 94 95 94 89 82

240 09 00 10 & 240 09 00 11 Calve rt Cal vert M D 90 91 89 *** *** *** ***

240 17 00 10 Charles S. Ma ryla nd M D 104 101 96 94 94 91 88 240 21 00 37 Frederick F rederick Municipal Ai rport M D *** 92 91 91 88 83 78 240 31 30 01 Montg omery Rock vil le M D 95 90 89 89 88 83 80 240 33 00 02 Prince Georg e's Greenb elt M D 106 99 97 95 93 *** *** 240 33 80 01 Prince Georg e's Suitland M D 99 94 93 *** *** *** *** 240 33 80 03 Prince Georg e's Equestria n Center M D *** *** *** *** *** 94 91 510 13 00 20 Arlingto n Co Aurora Hi lls VA 97 92 92 96 99 95 87 510 59 00 05 Fairfa x Chantilly ( Cub Run) VA 91 91 88 88 89 84 79 510 59 00 18 Fairfa x Mount Verno n VA 96 97 95 97 97 96 91 510 59 00 30 Fairfa x F ranco nia VA *** 90 89 92 97 96 89
510 59 10 04 & 510 59 10 05 Fairfa x Seven Corners & Ann an dale VA 95 90 *** *** *** 94 86

510 59 50 01 Fairfa x M cLea n – Le winsville VA 86 86 86 90 88 86 79 511 07 10 05 Lou do un Ashburn VA *** 89 86 90 92 88 *** 511 53 00 09 Prince W i ll ia m James S. Long PARK VA 91 88 85 85 87 83 79
515 10 00 09 Alexandria ( City) Ale xandria VA 91 89 88 90 92 88 81

Jeffe rson Co., NY (C lassif ication : MODERATE ) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 22

360 45 00 02 Jeffe rson Perch Ri ver NY 90 82 87 91 97 86 81

Greater Connectic ut, C T ( Classi fication: MODERA TE) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 900 31 00 3 Hartford East Hartford C T 91 84 88 90 90 84 80 900 50 00 5 Litchfield Cornwall (Mohawk Mt) C T *** *** *** *** *** 89 87 900 50 00 6 Litchfield T or ringto n C T 97 93 *** *** *** *** *** 901 10 00 8 New Lond on Groton C T 94 87 90 89 93 88 85
901 31 00 1 To lland Staf ford C T 95 89 90 94 95 88 86

Bosto n- Lawre nce- W o r cester (E. MA), MA (Classi fication: MO DERATE) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 250 01 00 02 Barnst able T ru ro MA 95 89 96 93 95 88 86 250 05 10 02 Bristol Fairhaven MA 91 87 93 90 95 88 86 250 05 10 05 Bristol Easton MA 88 81 84 *** *** *** ***

250 07 00 01 Dukes W a m panoa g Labora tor y

– Martha’s Viney ard MA *** *** *** *** *** *** ***

250 09 50 05 Essex Lawre nce- Haverhill MA 74 68 63 70 *** *** *** 250 09 20 06 Essex Lyn n MA 93 86 86 90 93 87 83 250 09 40 04 Essex Newbur y MA 87 82 83 86 89 83 78

250 17 00 09 Middlesex USEPA Region 1 Lab – Chelms ford MA *** *** *** *** *** *** ***

250 17 11 02 Middlesex Stow MA *** 86 88 89 89 79 75 250 17 18 01 Middlesex Sudb ury MA *** *** *** *** *** *** *** 250 17 40 03 Middlesex W a lt ham MA 93 *** *** *** *** *** *** 250 21 30 03 Norfolk E Milton (Blue Hi ll) MA *** *** *** *** *** 91 85 250 25 00 41 Suffolk Boston- Long Island MA *** *** 84 89 91 86 81 250 25 00 42 Suffolk Boston- Ro xbury MA *** *** 66 72 76 71 68 250 25 10 03 Suffolk Chelsea MA 82 *** *** *** *** *** ***
250 27 00 15 W o rc ester W o r cester MA 94 88 85 85 86 *** 79

Providence (Al l RI ), RI ( Classif ication : MODERATE ) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 23

440 03 00 02 Kent W G reen wich RI 92 88 94 97 95 87 84 440 07 10 10 Providence E Providence RI *** *** 87 91 93 *** 82
440 09 00 07 W as hington Nar raga nse tt RI *** 85 92 93 95 90 89

Springfield ( W es tern MA), MA (C lassification: MO DERATE) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 250 03 40 02 Berkshire Adams MA *** *** *** *** 87 *** *** 230 13 00 03 Hampde n Agaw am MA 84 77 77 83 *** *** *** 250 13 00 08 Hampde n Chicopee MA 91 86 85 92 94 90 84 250 15 01 03 Hampshire South Hadle y (Amherst) MA 82 76 77 78 77 69 67
250 15 40 02 Hampshire W a r e MA 99 89 89 89 87 84 82

Poug hke epsie
, NY ( Classi fication: MODERA TE) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 360 27 00 07 Dutchess M illbrook NY 90 87 87 93 94 89 79 360 71 50 01 Orang e Valley Central NY 90 86 87 84 87 83 84
360 79 00 05 Putn am Mt N inham NY 94 89 89 92 93 89 86

Bosto n- Manchest er- Portsmouth (SE), N H (Classi fication: MODERA TE) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005
330 11 00 16 & 330 11 00 19 & 330 11 00 20 Hil lsborou gh Manchest er NH *** *** *** *** *** 75 70

330 11 10 10 & 330 11 10 11 Hil lsborou gh Nashua NH 89 81 83 85 87 84 80

330 15 00 09 & 330 15 00 15 & 330 15 00 14 Rockingh am Portsmouth NH 87 80 *** *** *** 80 75

330 15 00 13 Rockingh am Brentw oo d NH *** 69 76 80 *** *** ***
330 15 00 12 & 330 15 00 16 Rockingh am Rye NH 90 79 81 83 84 78 73

330 17 30 02 Strafford Rochester NH 81 76 75 77 80 *** ***DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 24

Kent and Quee n Ann e’s Cos., MD ( Classif ication : MARGINAL) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 240 29 00 02 Kent M ill ingt on M D 100 101 100 102 95 89 82

Lanc ast er, PA (C lassification: MA RGINAL) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 71 00 07 Lanc ast er Lancas ter PA 101 97 96 94 92 86 83

Portlan d, ME (C lassif ication : MARGINAL) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 230 05 00 27 Cumberlan d Portland ME *** *** *** *** *** *** *** 230 05 20 03 Cumberlan d Cape Eliza bet h ME 89 77 80 86 88 79 71
230 23 00 03 & 230 23 00 04 Sag ad ah oc Phippsb urg/ Ge orget ow n ( Reid State Park) ME 92 84 *** *** *** 79 70

230 31 30 02 Y ork Kittery ME 88 81 81 84 88 84 77 230 31 20 02 Y ork Kenn eb unk port ME 92 82 86 90 91 84 74
230 31 00 37 & 230 31 00 38 Y ork Holl is ME 76 72 *** *** *** 75 73

Buffalo-Niagara Falls, NY (C lassification: SUBPAR T 1) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 360 29 00 02 Erie Amherst NY 85 89 92 97 99 91 86
360 63 10 06 Niagara M iddlep ort NY 86 85 87 91 95 89 86

Yo un gsto wn- W a r ren-Sharon
, OH-PA ( Classif ication : SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 390 99 00 09 & 390 99 00 13 Mahoni ng Yo un gsto wn - Oakhill OH 91 89 86 87 89 85 80DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 25

391 55 00 08 & 391 55 00 11 Tr umbull W a r ren-T ru mbull Count y OH 95 91 88 90 95 91 86

391 55 00 09 Tr umbull Kinsman OH 95 91 87 87 90 87 83
420 85 01 00 Mercer Far rell PA 96 92 88 92 94 88 83

Pittsburg h- Beaver Valle y, PA ( Classi fication: SUBPART 1) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005

420 03 00 08 Allegh en y Lawre nceville PA 91 88 85 89 92 87 81

420 03 00 10 Allegh en y Pittsburg PA *** 91 92 93 93 86 84 420 03 00 67 Allegh en y South Faye tte PA 99 96 90 90 91 87 82 420 03 00 88 Allegh en y Penn H ills PA 92 91 88 *** *** *** *** 420 03 10 05 Allegh en y Har rison Township PA 101 94 92 95 92 87 81 420 05 00 01 Armstrong Kittanni ng PA 86 93 92 91 93 88 84 420 07 00 02 Beaver Hookstow n PA 92 89 88 90 94 90 84 420 07 00 05 Beaver Brighton Township PA 91 90 89 90 92 87 81 420 07 00 14 Beaver Beaver Fal ls PA 90 89 85 88 86 81 75 421 25 00 05 W as hington Charleroi PA 101 94 87 86 89 84 80
421 25 02 00 W as hington W a sh ingto n PA 91 88 86 86 88 82 81 421 25 50 01 W as hington F lorenc e PA 91 90 88 88 87 82 78
421 29 00 06 W es tmo relan d Mur rysville PA 85 81 80 81 84 81 80
421 29 00 08 W es tmo relan d Greensb urg PA *** *** 86 86 91 87 82

Jamesto wn , NY ( Classi fication: SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 360 13 00 06 Chaut au qu a Dunkirk NY *** *** 89 92 94 93 89
360 13 00 11 Chaut au qu a W e st fie ld NY 89 88 85 87 89 85 79

Hancock, Knox, Lincoln & W a ldo Cos., ME (Classi fication: SUBPART 1)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 230 13 00 04 Knox Port C lyd e ME 82 76 80 83 87 81 77 230 09 04 01 Hancock Schoo dic Point ME *** *** *** *** *** *** ***DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 26

230 09 00 01 Hancock Seaw all ME *** *** *** *** *** *** ***
230 09 01 01 & 230 09 01 03 Hancock Acadia National Park - M cFarland H ill ME 85 83 85 84 87 80 75

230 09 01 02 Hancock Acadia National Park - Cadillac M tn. ME 89 87 89 93 94 88 82

Franklin Co., PA ( Classif ication : SUBPART 1) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 55 00 01 Franklin Methodist H ill PA 97 95 92 94 93 85 75

Erie, PA (Classi fication: SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 49 00 03 Erie Erie PA 93 90 87 88 92 87 83

Essex Co. ( W h ite face Mtn.), NY (Classi fication: SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 360 31 00 02
360 31 00 03 Essex ( Wh ite face Mount ain above 1,90 0 foot elevation ) W h it eface Mountain Summit NY 80 *** *** 87 91 89 ***
W h it eface Mtn. Base NY 79 76 78 82 88 83 77DRAFT

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Allentow n- Bethl eh em-East on, PA ( Classif ication : SUBPART 1) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 77 00 04 Lehi gh Allentow n PA 100 97 96 93 91 88 85 420 95 00 25 Northampt on F reemans bur g PA 87 95 97 92 90 88 87
420 95 01 00 & 420 95 80 00 Northampt on Easton PA 93 90 91 89 89 86 82

Reading
, PA (C lassification: SUBPAR T 1) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 11 00 01 Berks Kutz to wn PA 92 89 90 87 84 *** ***
420 11 00 09 & 420 11 00 10 Berks Reading PA 96 92 95 92 91 83 80

Clearf ield and India na Cos., PA ( Classif ication : SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 63 00 04 India na Strongst ow n PA *** *** *** *** *** *** ***
420 33 40 00 Clearf ield Moshann on PA 93 87 83 87 90 85 82
Green e Co., PA (Classi fication: SUBPAR T 1) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 59 00 02 Green e Holbrook PA 97 96 92 90 89 84 81

York, PA ( Classi fication: SUBPART 1) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 01 00 02 Adams Bigler ville PA *** *** *** *** *** 80 76
421 33 00 08 Y ork York PA 94 93 90 92 89 86 82

Rochest er, NY ( Classi fication: SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 28

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 360 55 10 04 & 360 55 10 07 Monroe Rochester NY *** *** *** 85 88 79 73

361 17 30 01 W ayne W i l li am son NY 86 81 81 83 88 81 71

Alban y- Schenec ta dy- T roy, NY ( Classi fication: SUBPART 1) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 360 01 00 12 Alban y Albany

- Loud onville NY 80 77 80 83 86 80 76 360 83 00 04 Renssela er Gra fton State Park NY *** *** *** *** *** 86 80 360 91 00 04 Sarat og a Stillwater NY 84 80 84 *** 87 84 82
360 93 00 03 & 360 93 00 93 Sche nect ad y Schen ecta dy NY 75 71 75 76 81 76 74

Harrisburg-Leb an on- Car lisle, PA ( Classi fication: SUBPART 1) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 43 04 01 Daup hin Har risburg PA 92 90 86 87 86 82 78 420 43 11 00 Daup hin Hershey PA 94 93 94 91 88 81 78
420 99 03 01 Perry Little Buffalo Stat e Park PA 90 85 84 83 87 80 78

Johnst ow n, PA ( Classi fication: SUBPART 1) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 21 00 11 Cambria Johnst ow n PA 93 91 88 88 87 80 77DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 29

Scrant on- W i lk es -Barre, PA (Classi fication: SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 69 01 01 Lacka wa nn a Peckv ille PA 90 87 86 85 85 80 75 420 69 20 06 Lacka wa nn a Scranto n PA 88 84 84 83 84 79 76 420 79 11 00 Lu zern e Nanticoke PA 82 81 82 83 84 78 73 420 79 11 01 Lu zern e W i l ke s-Barre PA 92 84 84 84 86 81 77

State College, PA ( Classi fication: SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 27 01 00 Centre State College PA *** *** *** 85 86 82 79
420 27 40 00 Centre Penn Nursery PA 90 84 80 82 88 84 ***

Ti oga Co., PA ( Classi fication: SUBPART 1) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 421 17 40 00 Ti oga T ioga PA *** *** *** 84 86 85 81

Altoo na, PA (C lassif ication : SUBPART 1) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 13 08 01 Blair Altoon a PA 95 89 84 84 85 81 77

W as hington Co. ( Hagerst ow n), M D (C lassification: SUBPAR T 1) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 240 43 00 09 W as hington Hagerstow n M D *** *** 85 87 86 83 78DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 30

New York ( Classi fication: AT TAIN MENT ) 8-hr Ozon e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 360 15 00 03 Glouces ter Elm ira NY 79 79 79 81 83 77 70 360 41 00 05 Hamilton Piseco Lake NY 79 77 77 79 81 76 73 360 43 00 05 Herkimer N icks Lake NY 72 70 72 74 76 72 69 360 53 00 06 Madison Camp Georg et ow n NY 79 78 78 80 82 77 73 360 65 00 04 Oneid a Camden NY 76 73 76 78 83 78 72 360 67 10 15 Ono nd ag a East Syrac use NY 82 80 81 83 85 *** 74 360 75 00 03 Oswe go Fulton NY *** *** *** *** *** *** 82
361 11 10 05 Ulster Belleayr e Mountain NY 83 80 81 81 83 80 79

Maine (Classi fication: A TT AINMEN T) 8-hr Oz on e DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 230 11 20 05 Ken ne bec Gardiner ME 77 73 75 78 80 76 70 230 09 03 01 Hancock Castine ME *** *** *** *** *** 75 70 230 21 00 03 Piscata quis Do ver-Fo xcroft ME *** 62 65 *** *** *** *** 230 19 40 08 Pen obsc ot Holden ME 75 *** 76 *** 83 75 68 230 17 30 01 Ox ford North Lovell ME 59 58 61 60 62 60 61 CC0040 00 2 NB CA N Roosevelt-Campob ello IP NB 62 60 61 60 61 54 54 230 19 40 07 Pen obsc ot Howlan d ME 71 68 69 68 68 64 61
230 03 80 01 Aroost ook Ashland ME 65 62 64 65 64 63 60

Pen nsylvani a (Classi fication: A TT AINMEN T) 8-hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 420 73 00 15 La wrenc e New Castle PA 83 78 78 78 80 77 73 420 81 01 00 Lyc oming Montoursville PA *** *** *** *** *** 82 79 420 81 04 03 Lyc oming W i l li am sport PA 74 71 71 *** *** *** ***
420 81 40 00 Lyc oming T iadagh to n PA *** 77 76 79 80 77 ***

Vermont (Classi fication: A TT AINMEN T) 8-hr Oz on e DESIGN VALUE (ppb)DRAFT

– The Nature of the Ozone Air Quality Problem in the Northeast: A Conceptual D escription Page 31

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 500 03 00 04 Ben ning to n Bennin gt on VT 80 76 79 80 80 78 73
500 07 00 07 Chitten de n Underhill VT 74 74 75 77 78 76 71

New Hampshire (C lassification: A TT AINMEN T) 8- hr Ozo ne DESIGN VALUE (ppb)

AQS MONIT OR ID COUN TY MO NITOR NAME ST 1997- 199 9 199 8-

2000 1999-

200 1 200 0-

2002 2001-

200 3 200 2-

2004 2003-

2005 330 01 20 03 & 330 01 20 04 Belkna p Laconi a NH 68 *** *** *** 78 75 73

330 03 10 02 Carroll Conwa y NH 67 64 66 67 *** *** *** 330 05 00 07 Cheshire Keen e NH 75 71 72 73 76 74 71 330 07 40 02 Coos Mt W a sh ingto n Base NH *** *** *** *** *** *** 67 330 07 40 03 Coos Pittsburg NH *** *** *** *** *** *** 60
330 09 00 08 & 330 09 20 05 Grafton Ha verhill-Leba no n NH 70 70 69 68 72 72 71

330 11 50 01 Hil lsborou gh Peterb orou gh ( Miller State Park) NH *** *** *** *** *** *** 77

330 17 00 07 & 330 17 10 07 Strafford Concord NH 74 71 70 74 75 75 71

330 19 00 03 Sullivan C laremont NH 73 70 72 73 75 77 72The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



# Appendix E: The s ea bre e ze and fl ow ove r

the oc ean in-dep thThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2



## Appendi x E: The sea br ee z e and f lo w over the ocean in- depth

Figure E-1 displa ys a general de scription of ozone transport in coastal New England. This figure sho ws 90 th percenti le ozone concentration wind direction plots at four sites along the coast. For the first site, L yn n, M A, high ozone day s are affected

ma inl y by wind s from the southwest bringing ozone up the coast to the site. At the second site, Newbury
, M A, winds arrive to the site from two directions, up the coast, in a simi lar pattern seen at L yn n, but also from the ocean. The high ozone da ys therefore can result from ozone and its precursors com ing from inland or from the ocean in the sea breeze. At the two northern sites in Maine, Cape Elizabe th and Acadia National Park, winds on high ozone day s come mostl y off the ocean. This is main l y due to the orientat ion of the Maine coastline, as s um me rti me winds generall y co me from the southwest, therefore traveling over the ocean before arriving to these sites.

A G E D TR A N S PO RT

LONG RA

NG E

TR A NSP OR T 9 0 th percen t i l e O zon e co n cen tr a tio n w in d dir e ct i o n fr eq u en cy plot s Lo ca l and tr an sp orte d
ozon e/ p r ec ur so r s i n the lan d / s eab r ee ze
r ecir cu lat ion p a tt e r n

A G E D TR A N S PO RT

LONG RA

NG E

TR A NSP OR T 9 0 th percen t i l e O zon e co n cen tr a tio n w in d dir e ct i o n fr eq u en cy plot s Lo ca l and tr an sp orte d
ozon e/ p r ec ur so r s i n the lan d / s eab r ee ze
r ecir cu lat ion p a tt e r n

A G E D TR A N S PO RT

LONG RA

NG E

TR A NSP OR T 9 0 th percen t i l e O zon e co n cen tr a tio n w in d dir e ct i o n fr eq u en cy plot s Lo ca l and tr an sp orte d
ozon e/ p r ec ur so r s i n the lan d / s eab r ee ze
r ecir cu lat ion p a tt e r n

Figur e E- 1. 90th percentile o zone concentration wind direction frequen c y plots at four coastal sites in northern New England

(figu re provided by Tom Downs, Maine Department of Environmental Protection).

Figure E-2 displa ys wind directions at Newbury
, M A on June 29, 1997 w here hourl y ozone concentrat ions ranged from 88 ppb to 107 ppb during the afternoon hour s and a sea breeze can be identified. The forward trajector y starting in Boston at 6 a.m. show s winds pushing air from the Boston m etro area out into the harbor throughout theThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

da y. The hourl y

ozone wind rose at Newbur y, MA show s the afternoon wind s hift that occurred on this da y w here vector direction indicates wind direction and magn itude indicat es ozone concentrat ions. Morning winds came from a west/northwesterl y direction when hourl y ozone concentrat ions at the site ranged from 47 to 68 ppb. At 1 p.m., the wind shifted direction, now coming off the ocean from the southeast, accomp anied by a 20 ppb increase in hourly ozone. Hourl y ozone levels then continued to increase in the earl y afternoon, peaking at 107 ppb at 3 p.m. This increase in ozone levels acco mpan y in g
a s hift in winds pushing air m asses from the ocean to a coastal site illustrat es ho w the sea breeze can contribute to poor air qualit y along the coast. The poor air qualit y could be a result of polluted

air from Boston being pu shed back to the site in the sea breeze. Sea breezes, however, are not alway s associated with worsening air qualit y as the afternoon sea breeze doesn’t alway s bring in polluted air.

0 0

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1 8 1 1 8 2 1 8 3 1 8 4 1 8 5 1 8 6 1 8 7 1 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8 1 9 9 2 00 2 01 2 0 2 2 0 3 2 0 4 2 0 5 2 06 2 0 7 2 0 8 2 0 9 2 1 0 2 1 1 2 1 2 2 1 3 2 1 4 2 1 5 2 1 6 2 1 7 2 1 8 2 1 9 2 2 0 2 2 1 2 2 2 2 2 3 2 2 4 2 2 5 2 2 6 2 2 7 2 2 8 2 2 9 2 3 0 2 3 1 2 3 2 2 3 3 2 3 4 2 3 5 2 3 6 2 3 7 2 3 8 2 3 9 2 4 0 2 4 1 2 4 2 2 4 3 2 4 4 2 4 5 2 4 6 2 4 7 2 4 8 2 4 9 2 5 0 2 5 1 2 5 2 2 5 3 2 5 4 2 5 5 2 5 6 2 5 7 2 5 8 2 5 9 2 6 0 2 6 1 2 6 2 2 6 3 2 6 4 2 6 5 2 6 6 2 6 7 2 6 8 2 6 9 2 7 0 2 7 1 2 7 2 2 7 3 2 7 4 2 7 5 2 7 6 2 7 7 2 7 8 2 7 9 2 8 0 2 8 1 2 8 2 2 8 3 2 8 4 2 8 5 2 8 6 2 8 7 2 8 8 2 8 9 2 9 0 2 9 1 2 9 2 2 9 3 2 9 4 2 9 5 2 9 6 2 9 7 2 9 8 2 9 9 3 0

0 3 0 1 3 02 3 0 3 3 0 4 3 0 5 3 0 6 3 0 7 3 0 8 3 0 9 3 1 0 3 1 1 3 1 2 3 1 3 3 1 4 3 1 5 3 1 6 3 1 7 3 1 8 3 1 9 3 2 0 3 2 1 3 2 2 3 2 3 3 2 4 3 2 5 3 2 6 3 2 7 3 2 8 3 2 9 3 3 0 3 3 1 3 3 2 3 3 3 3 3 4 3 3 5 3 3 6 3 3 7 3 3 8

3 3 9 3 4 0 3 4 1 3 4 2 3 4 3 3 4 4 3 4 5 3 4 6 3 4 7 3 4 8 3 4 9 3 5 0 3 5 1 3 5 2 3 5 3 3 5 4 3 5 5 3 5 6 3 5 7 3 5 8 3 5 9

3 6 0

6 A M

- 1 2 P M
1 P M

- 5 P M

F o r w ar d T raje c to r

y f ro m Bo ston Start T im e: 6 A M Boston, M A Ne w bur y , M A

0 0.02 0.04 0.06 0.08 0.1 0.12

6 A M

- 12 P M
1 P M

- 5P M 0 0

. 0 2 0

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3 0 3 1 3 2 3 3

3 4 3 5 3 6

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1 4 0 1 4 1

1 4 2 1 4 3

1 4 4 1 4 5

1 4 6 1 4 7 1 4 8

1 4 9 1 5 0 1 5 1 1 5 2

1 5 3 1 5 4 1 5 5 1 5 6 1 5 7 1 5 8 1 5 9 1 6 0 1 6 1 1 6 2 1 6 3 1 6 4 1 6 5 1 6 6 1 6 7 1 6 8 1 6 9 1 7 0 1 7 1 1 7 2 1 7 3 1 7 4 1 7 5 1 7 6 1 7 7 1 7 8 1 7 9 1 8 0

1 8 1 1 8 2 1 8 3 1 8 4 1 8 5 1 8 6 1 8 7 1 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8 1 9 9 2 00 2 01 2 0 2 2 0 3 2 0 4 2 0 5 2 06 2 0 7 2 0 8 2 0 9 2 1 0 2 1 1 2 1 2 2 1 3 2 1 4 2 1 5 2 1 6 2 1 7 2 1 8 2 1 9 2 2 0 2 2 1 2 2 2 2 2 3 2 2 4 2 2 5 2 2 6 2 2 7 2 2 8 2 2 9 2 3 0 2 3 1 2 3 2 2 3 3 2 3 4 2 3 5 2 3 6 2 3 7 2 3 8 2 3 9 2 4 0 2 4 1 2 4 2 2 4 3 2 4 4 2 4 5 2 4 6 2 4 7 2 4 8 2 4 9 2 5 0 2 5 1 2 5 2 2 5 3 2 5 4 2 5 5 2 5 6 2 5 7 2 5 8 2 5 9 2 6 0 2 6 1 2 6 2 2 6 3 2 6 4 2 6 5 2 6 6 2 6 7 2 6 8 2 6 9 2 7 0 2 7 1 2 7 2 2 7 3 2 7 4 2 7 5 2 7 6 2 7 7 2 7 8 2 7 9 2 8 0 2 8 1 2 8 2 2 8 3 2 8 4 2 8 5 2 8 6 2 8 7 2 8 8 2 8 9 2 9 0 2 9 1 2 9 2 2 9 3 2 9 4 2 9 5 2 9 6 2 9 7 2 9 8 2 9 9 3 0

0 3 0 1 3 02 3 0 3 3 0 4 3 0 5 3 0 6 3 0 7 3 0 8 3 0 9 3 1 0 3 1 1 3 1 2 3 1 3 3 1 4 3 1 5 3 1 6 3 1 7 3 1 8 3 1 9 3 2 0 3 2 1 3 2 2 3 2 3 3 2 4 3 2 5 3 2 6 3 2 7 3 2 8 3 2 9 3 3 0 3 3 1 3 3 2 3 3 3 3 3 4 3 3 5 3 3 6 3 3 7 3 3 8

3 3 9 3 4 0 3 4 1 3 4 2 3 4 3 3 4 4 3 4 5 3 4 6 3 4 7 3 4 8 3 4 9 3 5 0 3 5 1 3 5 2 3 5 3 3 5 4 3 5 5 3 5 6 3 5 7 3 5 8 3 5 9

3 6 0

6 A M

- 1 2 P M
1 P M

- 5 P M

F o r w ar d T raje c to r

y f ro m Bo ston Start T im e: 6 A M Boston, M A Ne w bur y , M A

0 0.02 0.04 0.06 0.08 0.1 0.12

6 A M

- 12 P M
1 P M

- 5P M

Figur e E- 2. E xample of

a sea breeze effect

occurrin g i n Newbury , MA on J une 29, 1997 (figu re data provided by To m Downs, Maine Department of Environmental Protection).

At sites further north in Maine, the sea breeze effect is less drama tic due to the orientat ion of the Maine coastline. Figure E-3 show s a similar ozone wind rose plot for Cape Elizabeth, ME on the same day illustrat ed in Figure E-2. With the exception of the winds at 6 a.m. that ca me from the northwest, the winds arrived to the site fromthe southwest direction. There are some slight shifts in wind direction, particularl y a shift after 5 p.m. that began to bring wind s from the inland side of the coast, but it is difficult to determ ine whether these shifts are due to a sea breeze effect or if the evening s hift is due to the weakened

sea breeze. Winds are generall y mov ing up the coast, over water,The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

and wind s in the same direction of the sea breeze can bring poor air qualit y

. O n this day
, ozone concentrations ranged between 89 and 102 ppb between 3 p.m. and 7 p.m.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

0 0

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. 0 8 0. 1 0

. 1 2

6A M

- 1 2P M 1P M

- 4 PM 5P M

- 6 PM

Forw ard Tr a je ctory f r o m Boston

S t ar t Time: 6A M Ca p e Eliz a be t h, M E

Bo s ton , MA 0 0

. 0 2 0

. 0 4 0

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. 1 2

6 A M- 1 2 P M 1 P M- 4 P M 5 P M- 6 P M 0 0

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. 0 6 0

. 0 8 0. 1 0

. 1 2

6A M

- 1 2P M 1P M

- 4 PM 5P M

- 6 PM

Forw ard Tr a je ctory f r o m Boston

S t ar t Time: 6A M Ca p e Eliz a be t h, M E

Bo s ton , MA 0 0

. 0 2 0

. 0 4 0

. 0 6 0

. 0 8 0. 1 0

. 1 2

6A M

- 1 2P M 1P M

- 4 PM 5P M

- 6 PM

Forw ard Tr a je ctory f r o m Boston

S t ar t Time: 6A M 0 0

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. 0 6 0

. 0 8 0. 1 0

. 1 2

6A M

- 1 2P M 1P M

- 4 PM 5P M

- 6 PM

Forw ard Tr a je ctory f r o m Boston

S t ar t Time: 6A M 0 0

. 0 2 0

. 0 4 0

. 0 6 0

. 0 8 0. 1 0

. 1 2

6A M

- 1 2P M 1P M

- 4 PM 5P M

- 6 PM

Forw ard Tr a je ctory f r o m Boston

S t ar t Time: 6A M Ca p e Eliz a be t h, M E

Bo s ton , MA 0 0

. 0 2 0

. 0 4 0

. 0 6 0

. 0 8 0

. 1 0

. 1 2

6 A M- 1 2 P M 1 P M- 4 P M 5 P M- 6 P M

Figur e E- 3. W ind directions and o zone concentrations at Cape Eli zabeth, ME on J une 29, 1997 (figu re data provided by To m Downs, Maine Department of Environmental Protection).

Transport over the ocean is co mm onl y ob served down wind of the New Y ork Cit y
me tropoli tan area during the summ er months due its proximit y to the Atlantic Ocean and the Long Island Sound. The four pollution rose plots presented in Figure E-4 represent the frequenc y of wind direction on the highest 10 percenti le ozone concentration day s from A pril 1 to October

31 during the ye ars 1997 to 2005. The wind s on the highest

ozone day s point at

the N ew York City m etropol itan area at all locations along the Connecticu t shoreline. Going along the Connecticut s horeline to the east (towards Groton), the predomin ant wind frequenc y direction s hifts increasingl y to the west, tracking the upwind location of the New Y ork Cit y metropo lit an area.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6

Figur e E- 4. W ind rose p lots along Connecticut shoreline for t he t ime period April 1 to October31 during the y ea rs 1997 t

hrough 2005. The elongated red ou tlines point ing to the southwest to west are wind directions on t

he highest 10 percentile oz one concentration da ys at four Connecticut coastal locations. For comparison, the blue outl ines are the wind rose plo ts for all day s over the same period. The h igh ozone da y wind rose plo ts indicate pol lution flow over Lo ng I sland Sound that tracks the upwind location of the New York C it y metropolitan area (figure from Tom Downs, Maine Department of the Environment). Eac h plo t s ho ws f

r eque nc y
o f hig h o zo ne incre a s e s a s the wind po ints up L IS to w a r ds em is sio n

- rich a r e a s
o f the Northe a s t c o r

rido r

.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



# Appendix F : O bserv ed noc turnal l ow l eve l je t

acros s the OTR, July 2002The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2



## Appendi x F: Observed nocturnal lo w level jet acr oss the OTR, July 2002

An examp le of the nocturnal low level jet across the OTR can be seen on the nights of J ul y 22 through July 24, 2002, as night time winds at altitud es between 450 m and 1500 m were observed at several coastal sites. Figure F-1 show s wind profiler data on the night of J ul y 22-J ul y 23, 2002 for five sites along the east coast: Fort Meade, MD (FME), Orange, MA ( ORE), Sto w, MA ( STW), Appledore Island, ME ( ADI), and Pease Air Force Ba se, N H (PSE). These wind “barb” plots show wind direction (direction of arrow indicat ing where wind is com ing from), wind speed ( wind barb color), ti me of day (UTC ti me, x-axis), and altitude (met ers, y- axis). The location of the nocturnal low level jet appears within the circle in each wind barb plot of Figure F-1. The figure s hows a weak nocturnal low level j et at the southernmost site, Fort Meade, with wind speeds of 15 to 25 knots between 300 m and 500 m in the earl y part of the night. F urther north, the nocturnal low level j et is more pronounced with wind speeds between 500 m and 1500 m above ground reaching 40 knots. Figure F-1 sho ws on this da y the nocturnal low level jet extending from Mary la nd up through s outhern Maine. In addition, the wind barb plots show the northeasterl y direction of the nocturnal low level jet. Above this jet, we see slower winds coming from the we st to all the sites.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

7. 2 2

. 0 2

- 7.2 3

. 0 2

FM E OR E S T W A D I PSE

D ir ec t io n o f LL J

7. 2 2

. 0 2

- 7.2 3

. 0 2

FM E OR E S T W A D I PSE

D ir ec t io n o f LL J

Figur e F

- 1 . Nocturnal low level je t on Ju l y 22 – 23, 2002 . Note: Circles i n the wind barb plots ind icate the location of

t he nocturnal l ow level jet.
Figure F -1 show s that throughout the night, the nocturnal low level jet travels in a northeasterl y direction along the east coast. The pollution imp lic ations of this nocturnal low level jet episode can be seen in Figure F-2. The Cadillac M ountain ozone monitor is located on the coast of Maine at an elevation of 466 m. At this elevat ed position, we can see how the nocturnal low level jet affects overnight and earl y morning ozone levels. Between midn ight and 4 a.m. during the northeasterl y nocturnal low level jet, hourly

ozone concentrations at Cadillac M ountain are between 70 ppb and 80 ppb. Ozone levelsThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4

had begun to increase earl y in the evening on J ul y 22 and continued to increase throughout the night and peak at 3 a.m. This increasing nighttim e ozone at an elevated position corresponds to the nocturnal low level jet channeling air up the coast during the night. Conversely
, at Cape Elizabeth, a ground level site relativel y close to Cadillac Mountain, night time ozone levels are much lower than on top of Cadilla c Mountain. This difference in ozone at

upper and lower levels s hows ho w the nocturnal inversion can isolate air masses above and below the inversion.

A DI PSE

D ire ction of L L J C a dillac

M o u nta in

C a pe E li z a be th 0 2 0 4 0 6 0 8 0 1 0 0 1 2 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00

7/22/20 0 2 7/2 3 / 2 0 02OzoneConcentration(ppb)

C adi l l ac M o u n t a i n C ape E l i z abet h T ime of LLJ

A DI PSE

D ire ction of L L J C a dillac

M o u nta in

C a pe E li z a be th 0 2 0 4 0 6 0 8 0 1 0 0 1 2 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00

7/22/20 0 2 7/2 3 / 2 0 02OzoneConcentration(ppb)

C adi l l ac M o u n t a i n C ape E l i z abet h T ime of LLJ

A DI PSE

D ire ction of L L J C a dillac

M o u nta in

C a pe E li z a be th 0 2 0 4 0 6 0 8 0 1 0 0 1 2 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00

7/22/20 0 2 7/2 3 / 2 0 02OzoneConcentration(ppb)

C adi l l ac M o u n t a i n C ape E l i z abet h T ime of LLJ

Figur e F- 2. Nocturnal low level je t with hourl y ozone concentrations at Cadillac Moun tain, ME and Cape Eli zabeth, ME on J uly 22 – 23, 2002. Note: C ircles in the wind barb p lots indicate t he l ocation of the nocturnal low level jet.

The air m ass affecting earl y morning ozone concentrations in Figure F-2 can be roughl y tracked u sing wind s peed and wind direction informat ion from Cadillac Mountain, Pease, Appledore I sland, and Orange. As suming the nocturnal low level j et occurs for five hours that night (based on neighboring wind barb plots), the air mass arriving at Cadillac M ountain at 3 a.m. during peak ozone conditions wa s over central Massachusetts around 11 p.m. on July 22 when the nocturnal low level jet began to form. Tracking this farther

back sho ws that the air mass affecting Cadillac Mountain wa s over western Connecticu t around 6 p.m. on J ul y 22. Looking at ozone levels in Corn wall, CT, we see that high ozone conditions existed in this region during the afternoon of July 22 with the average hourl y ozone at 112 ppb between 4 p.m. and 7 p.m. Elevated ozone from this region first slo wl y traveled up the coast in the evening. When the nocturnal low levelThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 5

jet formed, it quickl y pushed ozone up the coast affecting ozone levels at Cadillac Mountain, an elevated site in the jet, in the earl y morning hour s (~3 a.m.). Figure F -3 show s wind profiler inform ation for the next da y, July 24, 2002. In this

case we see a stronger nocturnal low level j et between midn ight and 8am that originates furtherto the s outh. The Fort Meade and Rutgers (RUT) sites s how the nocturnal low level jet in the earl y part of the evening with flow in the northeasterl y direction. At higher altitud es slo wer wind s from the west pass over the nocturnal low level jet. Further north,

a strong nocturnal low level j et can be s een at Stow, Appledore I sland, and Pease. It is difficult to deter mine if a nocturnal low level j et exists at O range as high winds continue at the upper

altitudes and data are missing for the highest altitud es. Figure F-3 demonstr ates an exampl e of the nocturnal low level jet pas sing along the east coast as far south as Mar yl and and as far north as southern Maine.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 6

Figur e F- 3. Nocturnal low level je t on Ju l y 23

– 24, 2002. Note: Circles i n the wind barb plots ind icate the location of

t he nocturnal l ow level jet. Data are inconclusive for identify in g a nocturnal l ow level jet at Oran ge, MA. FME OR E S T W A D I P SE

R UT

Direc

tio n o f LLJ FME OR E S T W A D I P SE

R UT

Direc

tio n o f LLJThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 7

Figure F -3 show s that the nocturnal low level jet occurred on the night of July 23- 24 as it did on the previous night. Figure F-4 s hows ozone levels overnight on the July 23-24 at Cadillac M ountain and Cape Elizabe th. In this case, we see that low ozone is occurring at both sites during the earl y hours of J ul y 24. A ppl yi ng the same me thods utiliz ed earlier, wind s peed and wind direction infor mat ion from Cadilla c Mountain indicat e that the air arriving at Cadillac Mountain was also roughly over central Massachusetts at 10 p.m. on July 23 (same wind direction and wind speed a s previous da y)

. Wind profiler

data sho w that winds moved this air mass from eastern New York and w estern Connecticut

in the late afternoon. Average ozone levels between 4 p.m. and 7 p.m. were 53 ppb at Cornwall, CT. Therefore, much like on the previous day
, air

masses were tracked back to the we stern Connecticut area upwind. In this case, however, low levels of ozone existed in the air mass.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 8

Figur e F- 4. Nocturnal low level je t with hourl y ozone concentrations at Cadillac Moun tain, ME and Cape Eli zabeth, ME on J uly 23 – 24, 2002. Note: C ircles in the wind barb p lots indicate t he l ocation of the nocturnal low level jet. Data are inconclusive for identify in g a nocturnal low level jet at Orange, MA.

Exa mining the wind profiler data from 4 p.m. to m idnight on J ul y 23 (Figure F-1 and Figure F-3), we s ee high winds at all altitud es developing throughout the region. Figure F -5 show s that these high winds are part of a weather front that passed through the region in the afternoon of J ul y 23. This corresponds with the sharp drop in ozone levels at Cornwall, CT, Cadillac Mountain, ME, and Cape Elizab eth, ME (Figure F -6 ) as the front pushed ozone out of the region. This explains the low levels of ozone seen at Cadillac Mountain during the nocturnal low level jet in the earl y hour s of Jul y 24. This exampl e demonstr ates that not all nocturnal low level j ets are associated with high ozone levels at elevated sites. A necessary condition for the transport of ozone in a nocturnal low level jet is the presence of upwind elevat ed ozone levels. The front that pushed through the region on the previous day resulted in “clean” air being transported in the nocturnal low level jet. FM E O RE ST W

RUT

Dire c tio n of

LLJ C adi llac

M ountai n

Ca pe El iz ab eth 0 2 0 4 0 6 0 8 0 10 0 12 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00

7 /23 /2 0 0 2 7 /2 4 /2 00 2OzoneConcentration(ppb)

Ca di l l ac M oun t a i n

Ca pe El i z a b e t h T ime o f L L J

FM E O RE ST W

RUT

Dire c tio n of

LLJ C adi llac

M ountai n

Ca pe El iz ab eth 0 2 0 4 0 6 0 8 0 10 0 12 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00

7 /23 /2 0 0 2 7 /2 4 /2 00 2OzoneConcentration(ppb)

Ca di l l ac M oun t a i n

Ca pe El i z a b e t h T ime o f L L J

0 2 0 4 0 6 0 8 0 10 0 12 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00

7 /23 /2 0 0 2 7 /2 4 /2 00 2OzoneConcentration(ppb)

Ca di l l ac M oun t a i n

Ca pe El i z a b e t h T ime o f L L JThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 9

8 AM 7 .23.0 2 8P M 7.2 3.02

Figur e F- 5. Weather map display in g a front passing t hrough t he East on Ju l y

23, 2002.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 10

0 2 0 4 0 6 0 8 0 1 0 0 1 2 00:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00OzoneConcentration(ppb)

C o r n w a l l C T C a pe E l i z a be t h
, M E C a di l l ac M o u n t a i n

Figur e F- 6. Hourl y o zone concentr ations on J uly 23, 2002 at three sites.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



# Appendix G: Contr ibutions t o the ozone res ervoi rThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 1



## Appendi x G: Contribution s to the o zone r eservoir
Contributions to the ozone reservoir can come from two sources. The first is from the residual local ozone and precursor s in the at mosphere at sun set. The s econd is from transport of ozone and precursor s from outside of the local region. To identif y these outside sources, Taubman et al . (2006) have mad e an anal y sis of the co mplet e set of aircraft flights undertaken b y RAM MPP between 1992 and 2003. Initiall y , the data were divided into morning and afternoon profiles to identif y diurnal patterns. Little diurnal variation wa s observed in the carbon monoxide and sulfur dioxide profiles. The ozone values were greater

in the afternoon than the morning, w hile ozone in the lower free troposphere (i.e., above the boundar y level), where long range transport is possible, wa s consistentl y ~55 ppb. Transport patterns and source regions during s um me rti me haze and

ozone episodes were anal yz ed with a cluster anal ys is of backtrajector y data. Eight clusters were identified, w hich were then divided into morn ing and afternoon profiles. Table G-1 lists the characterist ics of each cluster, and Figure G-1 sho ws the back trajectories calcula ted for each profile divided b y cluster at an altitude of 2000 meters. The medi an profile values were calculated and statistica l differences were deter min ed using a nonparametr ic procedure. When the greatest trajector y densit y lay over the northern Ohio River Valle y , which ha s large NO X and sulfur dioxide sources, the results were large ozone values, a large SO 2 /CO ratio, large s cattering particles, and high aerosol optical depth over

the mid- Atlantic U.S. In contrast, relativel y clean conditions over the mid- Atlantic occurred when the greatest trajector y den sit y la y over the s outhern O hio RiverValle y and nearl y missed man y large NO X and SO 2 sources. The greatest afternoon

ozone values occurred during periods of stagnation that were most conducive to photoche mi cal production. The least pollution occurred when flow from the northnorthwest w as too fast for pollution to accu mul ate and when flow wa s from the north, where there are few urban or industrial sources.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 2

Figure G- 1: Map s of

the 2 km , 48 hr HY-SPLIT back trajectory clusters f or mi d- Atlantic region

Note: Cluster groupin gs ar e a) cluster 1 , b) cluster 2 , c ) cluster 3, d) cluster 4, e) c luster 5 , f) cluster 6, g) cluster 7, and h) cluster 8. Figure from Taubman et al.
, 2006

.The Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 3

Ozone transport over several hundred kilo met ers into the mid- Atlantic U.S. wa s esti mat ed b y

calcula ting the ratio of the residual la ye r ozone between 500 m and 2 km in the upwind morning profiles to the down wind afternoon boundary lay er values between 100 m and 2 km. The greatest level of transported ozone (69-82 percent) occurred when the maxi mu m trajector y densit y lay over the southern and northern Ohio River Valle y (clusters 1, 2, 4, and 6); ~59 percent of the total profiles). The least amoun t of transported

ozone (55-58 percent) wa s associated with fast southwesterl y flow (cluster 8; ~3 percent of the total profiles), fast north-northwesterl y flow or clean northerl y flow from regions with relativel y few urban or industrial pollution sources (clusters 5 and 7; ~6 percent of the total profiles), and stagnant conditions within the mid- Atlantic conducive to greater local ozone production (cluster 3; ~27 percent of the total profiles). The average amount of ozone transported into the Baltim ore- Washington urban corridor is 64 percent of the total ob served ozone in the afternoon boundary la ye r. If the background ozone is

remov ed, then this value is lowered to 55 percent. When trajector y den sit y plots were overlaid on maps with the largest annual N O X and S O 2 emi tters, specific source regions were identified. The results indicate that the

areas of maxi mu m trajector y densit y together with wind speed are effective predictors of regional pollution and loadings. A dditional l y, due to the Lagrangian nature of the dataset, the regionall y transported contribution to the total afternoon boundary la ye r column

ozone content

in each cluster

could be quantified.
Table G-1. Cluster group s for air ma ss trajectories into m id -Atlantic Region

Cluster Descrip tion Upw ind Region

1 L ar ge o zone values, large SO 2 / CO ratio, large h ighl y scatterin g particles. Moderate northwesterl y flow – ag ed point source air. Northern Ohio R iver Valle y

2 Small o zone values, large SO 2 / CO ratio. Northwesterl y flow at higher

wind speeds than Clu ster 1 – aged poin t

source air. Northern Ohio R iver Valle y,
e xtending into t he Great La kes region

3 L ar ge o zone values, smal l SO 2 /CO ratio. Stagnant conditions with l ight southerly flow. Central mid-Atlantic region

4 Small o zone values, smal l SO 2 /CO ratio. Moderate southwesterl y flow, small po llution l oading – fewer point sources. S outhern Ohio R iver Valle y

5 Fairl y fast north-northwesterl y flow. Flow too fast for pollut ion to accumulate from source region. Northern GreatL akes

6 Moderatel y larg e ozone values, S O 2 /CO ratio ver y larg e, smaller less scattering particles. Northwesterl y flow, bu t faster wind s peeds than Clus ters 1 and 2. Crosses several large S O 2 and NO X sources. Northern Ohio R iver Valle y

7 L ea st pol lution of an y of the clusters. Flow is out of the north. Relativel y

cool, dr y continental air. Eastern Ontario, western Quebec

8 Small o zone values, smal l SO 2 /CO ratio. Fast southwest flow. Ver y few trajectories. Vicini t y of Te xasThe Nature of the Ozone Air Qualit y Problem in the Northeast: A Conceptual Description Page 4



### Reference
Taub man, B.F., J.C. Hains, A .M. Thompson, L.T. Marufu, B.G. D oddridge, J.W. Stehr, C.A. Peit y, and R.R. Dickerson. “A ircraft vertical profiles of trace ga s and aerosol pollution over the m id- Atlantic U nited States: Statistics and meteoro logica l cluster anal y sis. ” J

. Geophys

. Res

. 111 , D10S07, doi:10.1029/2005JD006196, 2006.