ATTACHMENT A 

Technical Support Document 

for 

Redesignation of the Boston-Manchester-Portsmouth (SE), NH 

8-Hour Ozone (1997 Standard) Nonattainment Area 
Technical Support Document 

for 

Redesignation of the Boston-Manchester-Portsmouth (SE), NH 

8-Hour Ozone (1997 Standard) Nonattainment Area 

September 2010 

~ NEW HAMPSHIRE 

DEPARTMENT OF 

Environmental 

= ° Services 

Air Resources Division 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page i 

Table of Contents 

1 . INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 

2. NATURE OF OZONE AIR QUALITY PROBLEM IN THE NORTHEAST . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 

2.1 OZONE PRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 

2.2 AIR POLLUTION TRANSPORT MECHANISMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 

2.2 .1 High-Elevation Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 

2 .2 .1 .1 Aircraft Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 

2 .2 .1 .2 Mt. Washington, New Hampshire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 

2.2 .1 .3 Pack Monadnock Mountain - Miller State Park, New Hampshire . . . . . . . . . . . . . . . . . . . . 9 

2.2 .2 Mid-Elevation Transport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 

2.2 .3 Low-Elevation Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 

2.2 .3 .1 Sea Breeze . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 

2.2 .3 .2 Offshore Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 

2.3 THE DEVELOPMENT OF AN OZONE EPISODE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 

2.4 NOx vs. VOC CONTROL STRATEGIES EFFECTIVENESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 

3. ATTAINMENT MODELING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 

3.1 MODELING METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 

3 .1 .1 Identification of Models and Domain Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 

3 .1 .2 Emissions Processing Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 

3 .1 .3 Meteorology Processing Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

3 .1 .4 Model Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 

3 .1 .5 Establishing Estimates of Future Design Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 

3 .2 CMAQ AND CALGRID MODELING RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 

3 .3 EPA's CAIR MODELING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page ii 

List of Figures 

Figure 2-1 Major Transport Regimes in the Northeast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 

Figure 2-2 Typical Day/Night Ozone Cycle at Ground Level and Aloft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 

Figure 2-3 Number of 8-Hour Ozone Events Exceeding 85 ppb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 

Figure 2-4 How Upper-Level Transport Works. . . . . . . . . : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 

Figure 2-5 Observed Vertical Ozone Profile Measured Above Poughkeepsie, NY . . . . . . . . . . . . . . . . . . . . .6 

Figure 2-6 Aircraft Ozone Observations in the Northeast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 

Figure 2-7 Comparison of Average and Hourly Summer Ozone Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Figure 2-8 Computer Model Illustration of the Low-Level Jet in the Northeast . . . . . . . . . . . . . . . . . . . . . . . . . .9 

Figure 2-9 How the Sea Breeze Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 

Figure 2-10 Offshore Ozone Measurements from the Scotia Prince . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 

Figure 2-11 Bermuda High Synoptic Scale Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 

Figure 3-1 Map of the CMAQ/CALGRID Modeling Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 

Figure 3-2 Map of the RPO National Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 

Figure 3-3 QA/QC Plot of Surface Source CO Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 

Figure 3-4 QA/QC Plot of Surface Source VOC Emissions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 

Figure 3-5 QA/QC Plot of Point Source NOx Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 

Figure 3-6 QA/QC Plot of Point Source S02 Emissions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 

Figure 3-7 QA/QC Plot of Humidity Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 

Figure 3-8 QA/QC Plot of Temperature Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Figure 3-9 QA/QC Plot of Rainfall Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 

Figure 3-10 Relative Bias between Maximum 8-Hour Ozone Concentrations Predicted 

with CALGRID and Observed Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 

Figure 3-11 Comparison of Modeled Maximum 8-Hour Ozone Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . 24 

Figure 3-12 CMAQ SIP-Quality Modeling Results for 2009 OTB/OTW vs. 2002 

Design Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 

Figure 3-13 Plot of 2009 Estimated Design Values for the OTC 2009 OTB/OTW Strategy . . . . . . . 27 

Figure 3-14 Plot of Differences in Predicted Maximum 8-Hour Ozone Concentrations 

between 2002 Base Case and the OTC 2009 OTB/OTW Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 

List of Tables 

Table 2-1 Night and Daytime Patterns of Ozone at Mt. Washington . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Table 3-1 Modeling Emissions Inventory: State-by-State Anthropogenic NOx . . . . . . . . . . . . . . . . . . . . . . .18 

Table 3-2 CMAQ Maximum Modeling Statistics for 2002 Base and 2009 OTB/OTW . . . . . . . . . . . 25 

Table 3-3 CALGRID Maximum Modeling Statistics for 2002 Base, 2009 OTB/OTW, 

and 2009 Sensitivity Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

Table 3-4 Modeling Summary for New Hampshire Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

Table 3-5 CAIR Modeling Results for New Hampshire for 8-hour Ozone (ppb) . . . . . . . . . . . . . . . . . . . . . 29 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 1 

1 . INTRODUCTION 

This document is provided in support of New Hampshire's request to EPA to redesignate the 

Boston-Manchester-Portsmouth (SE), NH nonattainment area (hereinafter referred to as the 

Southeast New Hampshire Nonattainment Area) to attainment status . On June 15, 2004, EPA 

officially classified this portion of New Hampshire as a moderate nonattainment area for the 1997 

8-hour ozone Ambient Air Quality Standard (NAAQS) of 0 .08 parts per million (ppm) (Federal 

Register, 69 FR 223857). For several years since this classification was made, the Southeast New 

Hampshire Nonattainment Area has been monitoring attainment for the 8-hour ozone standard under 

EPA's Clean Data Policy .* This nonattainment area is therefore eligible for redesignation to 

attainment in accordance with the provisions of the Clean Air Act (CAA). 

The information presented in this report is presented in two parts. The following section provides a 

conceptual description of the formation and transport of ozone in the Northeast. This information is 

useful in setting the context for New Hampshire's ozone redesignation request. Section 3 discusses 

a photochemical air quality modeling assessment that was undertaken in 2007 by New Hampshire 

and other Ozone Transport Region states . This modeling effort was performed in support of states' 

attainment demonstrations and for other SIP planning purposes, and is therefore not a specific 

component of this redesignation request. Nevertheless, it is presented here because it supports the 

conclusion that the improvement in New Hampshire's air quality is due to permanent, enforceable 

emissions control measures and is not simply an anomaly (due to cooler weather conditions, for 

example). 

* Using monitoring data for the period 2002-2007, EPA determined that the Southeast New Hampshire 8-hour Ozone 

Nonattainment Area (moderate) had reached attainment of the 8-hour ozone NAAQS. A final rule published on March 

18, 2008 (73 FR 14387), effective on that date, suspended the requirements for this area to submit an attainment 

demonstration, a reasonable further progress plan, contingency measures, and other State Implementation Plan elements 

related to attainment of the 8-hour ozone NAAQS. This determination is consistent with EPA's Clean Data Policy, which 

exempts the state from certain SIP requirements if the area has three consecutive years of air quality data showing it 

meets the NAAQS, for as long as the area continues to attain the standard. 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 2 

2. NATURE OF OZONE AIR QUALITY PROBLEM IN THE NORTHEAST 

In order to form an effective ozone reduction plan for the State of New Hampshire, an 

understanding of ozone formation, source areas, wind patterns, and transport is necessary. The 

formation and transport of ground level ozone is a complex phenomenon affected by several 

variables. 

2.1 Ozone Production 

Ozone is formed in the atmosphere when NOx combines with VOCs in the presence of sunlight. 

Consequently, solar energy, mixing conditions, and relative NOx and VOC concentrations within an 

air mass are paramount to ozone formation. 

Typically, high pressure systems cause an air mass to flow downward, a phenomenon which 

increases ground level ozone concentrations in at least four ways: 1) the sinking motion of the air 

mass under high pressures stabilizes the air mass, reducing cloud formation and resulting in an 

increase in solar energy, thus increasing photochemical activity ; 2) the sinking motion tends to keep 

locally produced precursor emissions nearer to the surface, thus limiting upward movement and 

dilution of the air mass; 3) ozone and its precursors, present at higher elevations (500 to 1500 

meters) as a result of transport, are pushed down toward the ground; and 4) the sinking air raises the 

ground level pressure, generating more heat at ground level. The result is a greater supply of ozone 

and precursors at or near ground level, more reaction energy in the form of heat and sunlight, and 

relatively limited dilution in the air mass. Additionally, the clockwise airflow pattern around a high 

pressure system transports pollutants northward and then eastward from the industrial Midwest or 

along the Northeast Urban Corridor to New England. These meteorological conditions are typical 

when New Hampshire monitors elevated levels of ground level ozone . 

2.2 Air Pollution Transport Mechanisms 

The predominant transport patterns in the Northeast were observed and documented in a study 

conducted by the North American Research Strategy for Tropospheric Ozone - Northeast 

(NARSTO/NE) entitled "Initial Results on Transport and Mixing Based on NARSTO-Northeast 

Data," and dated January 28, 1997 . This study identified three basic flow regimes : synoptic, 

channeled, and near surface (Figure 2-1) . 

0 

The Synoptic flow is the pattern of airflow at higher elevations (above 2600 feet). Synoptic 

flows are unaffected by large-scale frictional ground-level objects such as mountains, 

valleys, and lakes. 

Channeled flows occur at lower elevations (650 to 2600 feet) where synoptic flow patterns 

are interrupted by large objects such as mountains, hills, and valleys but are not affected by 

lower, smaller objects such as trees and buildings. 

Low-level jets occur nocturnally along the eastern edge of the Appalachians. Although they 

somewhat resemble channeled flow, low-level jets are compact, relatively high-speed 

airflows that occur just above ground level. The speed of flow is made possible by the 

compression of converging airflows and the frictionless surface caused by the nocturnal 

thermal inversion, which the jet rides on. 

Near-surface flows (below 650 feet) are affected by nearly all surface frictional objects, 

including trees and buildings. 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 3 

Synoptic flows are generally from west to east, transporting pollution from the Midwest to the 

Northeast, while channeled flows generally follow the Appalachian Mountains from southwest to 

northeast, transporting pollution from the Northeast urban corridor toward northern New England. 

Figure 2-1 - Major Transport Regimes in the Northeast 

Synoptic (higl}level) 

10 

Channeled (mid-levet) 

Low-Level 

-

Jets (nocturnal) 

Adapted from NARSTO 2000 and Research 

conducted bv the Un'wersitv of Marviand 

Long-range (synoptic scale) transport occurs from west to east across the Appalachian 

Mountains. Regional scale transport in channeled flows also occurs from west to east through 

gaps in the Appalachian Mountains and in nocturnal low level jets from southwest to northeast 

over the Northeast Corridor . Daytime sea breezes can affect local coastal areas by bringing in 

air pollution originally transported near the surface across water parallel to the coast (e .g ., 

along the Maine coastline) . Figure from NARSTO, 2000, citing Blumenthal et al., 1997. 

Absent transport, ground-level ozone concentrations increase during sunlight hours as a result of 

photochemical production and decrease substantially at night when ozone removal exceeds 

production (this is also known as diurnal variation or fluctuations within the daily cycle) . However, 

in areas such as New Hampshire, which are downwind of large urban regions, ozone concentrations 

often rise through the evening and/or early morning hours and peak between 6 :00 p .m. and 6:00 

a.m. due to transport from upwind sources. At higher elevations, concentrations of ozone and ozone 

precursors may remain high at night, since there is minimal downward mixing of the atmospheric 

transport layers at night. During daylight hours when solar energy heats the ground, the resulting 

warm air near the ground begins to rise . Rising air creates an unstable atmospheric situation 

resulting in the upward and downward mixing of air masses (including ozone transport layers) . 

Thus, ground level ozone concentrations typically rise for several hours immediately after sunrise 

(Figure 2-2). 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 4 

Figure 2-2 - Typical Day/Night Ozone Cycle at Ground Level and Aloft 

Solar ultraviolet energy helps to create ozone 

which is present in high quantities late in the day. 

At night, there is no ultraviolet sunlight to create 

ozone and ground level objects and gases act to 

remove ozone, resulting in the curve in blue, 

which represents ozone at ground level. Ozone at 

higher elevations, conversely, is often not 

depleted at night and may remain at elevated 

concentrations throughout the day (red curve) . 

NHDES investigated weather conditions that lead to poor air days in the state. Generally, the 

majority of the ozone transported into the state comes from the Northeast corridor (Washington, 

DC, Baltimore, Philadelphia, New York, and Boston regions) (see Figure 2-3) . On certain days, the 

Boston area provides the greatest amount of ozone along the immediate New Hampshire seacoast . 

The non-New England portion of the corridor provides the majority of the ozone for the remainder 

of New Hampshire. Air pollution contributions from the Midwest are significant and on some days 

provide the vast majority of pollution reaching New Hampshire . New Hampshire has its worst air 

pollution days when low-elevation winds come from the cities to our southwest (Northeast 

Corridor) and mid-elevation winds come from the Midwest. The smoggiest days occur when there 

is a slow airflow from the Midwest. 

Figure 2-3 - Number of 8-Hour Ozone Events Exceeding 85 ppb 

and Corresponding Wind Direction (1995-2002) 

45 .0- 

-73.0 -72.0 -71.0 

~: - Monitor Meets the 8-Hour 

Ozone Standard for Health . 

" - Monitor Does NOT Meet the 8-Hour, 

Ozone Standard )r Health 

44.0- 

43 .0'1 

Rochester starts 1996 

Miller S P . (elev=228 

upper-level 

ezene 

ground-level 

azare -

1 -- 

Scairise 51.aiset 

'l3ml:ottlay 

remont 

6 

Keene 

tt !li 

avarhill 

o Conway 

1& 

Lacon? 

Conc8rd Rochester 

Nknohester P"rCf~~ 

Miller S.P. 

7 

© 

Note: Brentwood starts 1999 

13 

ran 

starA 8/2002 

ou 

26 ' 42 . 

5.0 

4 .o 

iye 

41 

3.0 

42 .0 

Wind directions at the time 

unhealthy ozone levels were 

measured in New Hampshire 

between 1995 and 2002: There is 

an overwhelming trend of winds 

coming into the state from the 

southwest, with the exception of 

the seacoast area which also 

suffers from a sea breeze that 

brings pollution from the Boston 

metro area to coastline 

communities. (Numbers indicate 

the number of unhealthy days.) 

Source : NHDES 

-73.0 -72.0 -71.0 

Longitude 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 5 

2.2 .1 High-Elevation Transport 

Pollution transport should not be thought of only as a horizontal phenomenon. Pollutants can move 

upwards in the air and then travel downward in sinking air currents after being transported over 

great distances at elevations above 2,500 feet (Figure 2-4). 

Figure 2-4 - How Upper-Level Transport Works 

Air pollutants get picked up and carried by the 

upper level wind s . ® 

Pollutants can 

mix down the 

same way they 

came up 

Pollution 

Sources 

2.2 .1 .1 Aircraft Measurements 

Measurements several thousand feet above the ground may record much higher ozone overnight than 

that measured at ground level. For example, ozone aloft concentrations above Poughkeepsie, NY and 

New Haven, CT approached levels of 120 ppb or greater on the night of July 14 (Zhang & Rao, 1999). 

Figure 2-5 displays the aircraft measurements above Poughkeepsie, NY around 4 a.m. EST. 

Aircraft measurements by the NARSTO-NE during the July 1995 ozone episode also demonstrate 

the existence of significant transport into and within the region, contributing to exceedances of the 

ozone standard in Maine (Blumenthal et al ., 1997) . Several "spiral" flights a few thousand feet 

above Poughkeepsie, NY, Gettysburg, PA, and Shenandoah, VA, recorded ozone levels of 100 ppb 

or greater in the early morning (4 AM) on two days. One aircraft actually recorded an ozone 

concentration well above 120 ppb at an elevation of approximately 2600 feet above Poughkeepsie 

on July 14, 1995, when ground level ozone measured about 30 ppb. Another flight during the early 

morning of July 14, 1995, from Virginia to Maine recorded ozone levels in the range of 70 to 100 

ppb at an elevation of 1600 feet throughout the Northeast corridor. 

These elevated ozone concentrations measured in the early morning at high elevations suggest that 

the ozone and its precursors originated during the active times of the previous day (or days) and 

traveled up and away from the source locations. Spiral flights in the afternoon over the same three 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 6 

cities, measured uniform ozone levels from ground level to 2600 feet, showing that the air had 

become well mixed during the day and had thus brought transported ozone aloft down to the 

surface. A second flight along the length of the entire corridor showed that ozone levels at 1600 feet 

had risen well above 120 ppb in the Baltimore-Washington and New York metropolitan areas. 

Being well above the ground, this ozone was presumably destined to be transported further 

downwind overnight. 

Figure 2-5 - Observed Vertical Ozone Profile Measured Above Poughkeepsie, NY 

at about 4 AM EST on July 14,1995 

1600 

1200 

800 

w 

Q 

400 

8-hour standard 

. 

0 20 40 60 80 100 120 140 

fJzone (Ppb) 

Note . The fipm inchuies a ver&aI hue at $5 pPb for comparing alatt measurem=ts with the 

S-h= ozow hiAAQS (observed ozone data from Zhang & Rao* 1999). 

On behalf of the Mid-Atlantic Northeast Visibility Union (MANE-VU), additional aircraft 

measurements were taken to track a regional haze event in the Northeast in August of 2002 (Figure 

2-6). The aircraft measured light scattering from particles as well as ozone. Like the earlier 

NARSTO-NE measurements, the MANE-VU study found high levels of ozone aloft which were 

blowing toward the northeastern states . In most cases, the ozone measured aloft exceeded 

measurements collected at ground level, indicating that the ground-level ozone was not all created 

locally. It is also noteworthy that the preliminary measurements collected above Baltimore, MD 

were already rich in ozone, suggesting that a large amount of the pollutant was blowing into the 

region from upwind areas. It should be noted that ozone aloft is depleted much more slowly than 

ozone at ground level, which comes into contact with various surfaces and obstructions . This means 

that, once ozone is present at high elevations, it becomes more likely to travel long distances 

downwind without breaking down. 
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1) 

Figure 2-6 - Aircraft Ozone Observations in the Northeast 

Ozone Concentrations in ppb 

from MANE VU Flight 

August 14, 2002 

CnriC b( MaMU W.EStt6 

MEDEP.BAG 

Ozone measurements from 

aircraft observations 

compared to ground-based 

measurements. 

Source: MEDEP 

d00 m AGL47 PM RANGE OF 

W IND DIRECPIONS 

WIND PROFILER SITES 

Other aircraft measurements reinforce these observations . Clarke and Ching (1983) during the 

summer of 1979 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 

Hudson River Valley north of New York City down across eastern Pennsylvania and into Maryland 

just west of Baltimore. The measurements also observed NOx aloft during the overnight hours that 

could contribute to additional ozone formation in the Ozone Transport Region as it mixed down 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 just above the nocturnal inversion boundary. 

The pollutants in this reservoir are not subject to destruction at the surface and can be transported 

long distances in the wind flows created by the synoptic scale weather patterns conducive to ozone 

formation and transport. 

2.2 .1 .2 Mt. Washington, New Hampshire 

Mt. Washington in Pinkham Notch, New Hampshire, is tall enough (elev. 6288 feet) to reach well 

up into the upper ozone transport layers with minimal obstruction by other terrain features. Ozone 

levels recorded at the summit mirror NARSTO-NE findings, showing consistently elevated levels of 

ozone with little diurnal 'variation during most episodes - clear evidence of long range transport. As 

further evidence of long range transport, Camp Dodge (elev. 2400 feet), located at the base of Mt. 

Washington, usually records lower ozone concentrations than those seen contemporaneously at the 

summit. 
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Both monitors have no major NOx sources within 75 miles and no major sources upwind in the 

direction of prevailing winds for approximately 150 miles. Transport from more distant upwind 

sources is the primary source of ozone monitored at these sites. Since the summit of Mt. 

Washington is high enough to be exposed to high elevation transport (synoptic flows), downward 

mixing is not a factor in creating the peak ozone values it experiences . In fact, transport time from 

upwind source areas appears to be the single largest factor in determining the time at which the 

maximum ozone level occurs at the summit. Daily maximum ozone levels at Camp Dodge are 

dependent on inversion breakup caused by downward mixing from upper transport elevations, and 

thus are typically recorded during the afternoon hours. On the contrary, maximum ozone levels at 

the summit occur most often during the overnight hours, when no ozone is produced locally. The 

percent of daily one-hour ozone maxima which occur during the daylight heating hours and during 

the overnight hours on the summit of Mt. Washington and at Camp Dodge are listed in Table 2-1 . 

Table 2-1 - Night and Daytime Patterns of Ozone at Mt. Washington 

Mt. Washington Percent of Hourly Maxima Percent of Hourly Maxima 

Monitor Location During Daylight Hours During Overnight Hours 

(9 a.m. to 5 p.m.) (6 p.m. to 8 a.m.) 

Summit 18% 82% 

Base (Camp Dodge) 80% 20% 

Note: Daylight heating hours are hours of the day when solar energy drives vertical mixing of 

transport layers 

The difference in ozone concentrations at the summit and base can also be seen when looking at 

plots of maximum ozone levels at each site . The graph in Figure 2-7 is typical of summertime 

ozone at Mount Washington. 

Figure 2-7 - Comparison of Average and Hourly Summer Ozone Concentrations . 

at the Base and Summit of Mt. Washington 

Monitor Data for Mt. Washington, NH 

(Summit and Base) for 1996 

-IN. Wuhingtrm 

(ppb) 

-tn~vblo a 

-M Washiryem 

+"-as+Icvbl 

----C-P DAV 

puray. (ovb) 

Comparison of mountaintop 

(elev. 6288 ft) ozone with 

mountain base (elev. 2000± ft) 

hourly ozone: Often the ozone 

is higher in concentration at the 

summit due to pollution 

transport from distant sources. 

Many times the ozone at the 

base is driven by downward 

mixing from the upper transport 

layers during the day: 

Source : NHDES (Data: AMC) 
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2.2 .1 .3 Pack Monadnock Mountain - Miller State Park, New Hampshire 

A similar mountaintop air pollution monitor was established in 2002 in Miller State Park at, the 

summit of Pack Monadnock Mountain in Peterborough, NH (elevation 2288 feet) . The mountain is 

located in the south-central portion of New Hampshire in an ideal location to track air pollution 

transport into the state. The monitor is only a short distance from the heavily visited and hiked Mt. 

Monadnock. The early findings from this monitor are similar to those of Mt. Washington in that 

when an ozone or PM2.5 episode begins to build into the region, it is detected at higher elevations 

first where the stronger transport currents are located. The new Miller State Park monitor has been 

useful in tracking air pollution events entering the populated Merrimack Valley area (Nashua, 

Manchester, and Concord). 

2.2 .2 Mid-Elevation Transport 

Mid-elevation transport is usually dominated by the effects of large topographical features, such as 

mountains, which redirect airflows and cause a channeling of the wind. In the Northeast, channeled 

airflows may occur on either side (east or west) of the Appalachian Mountain range and also 

between the subranges that comprise the Appalachian chain. Unhealthy air quality can be present 

on one side of a mountain while just a few miles away on the other side, the air quality is 

substantially cleaner. This mid-layer is generally heavily influenced by the airshed layers above and 

below that mix polluted, or clean air into it . Pollutants can also be injected directly into this layer by 

some of the very tall smoke stacks (around 1000 feet tall) commonly found in the Midwest. 

Mid-level transport is often affected by a phenomenon known as the low-level jet (LLJ). It is called 

"low-level" because it is lower relative to the well known Jet Stream, a high elevation airflow that 

drives the movement of weather systems around the world. Recent advances in remote sensing 

instruments (i .e ., radar profilers) have allowed the LLJ phenomena to be observed. During the 

overnight and early morning hours, a LLJ frequently forms just east of the Appalachian Mountains. 

Once formed, the LLJ is a strong west to southwest wind flow that develops at low altitudes just 

above the nocturnal boundary layer. These winds typically reach speeds of 40-50 mph and are 

located at approximately 1,000-2,000 feet above the ground. Figure 2-8 depicts the LLJ observed 

during an August 2002 ozone event. 

Figure 2-8 - Computer Model Illustration of the Low-Level Jet in the Northeast 

9AOmb WkM(es/s) 0B/12/02 032 _ . 960mb Yind(m/s) OB/12/02 C42 

The low level jet 

(shown in red, orange, 

and yellow) normally 

sets up along the , 

eastern side of the 

Appalachian Mountains 

and flows from 

southwest to northeast. 

Source : 

University of Maryland 
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2.2 .3 Low-Elevation Transport 

A number of one-day and multi-day transport mechanisms- have been observed along the 

northeastern coastal plain. Blumenthal et al ., (1997) described several transport mechanisms, 

including near-surface flows that act within a thousand feet of the ground and are capable of 

transporting ozone and its precursors along the urban corridor as far as 160 miles during the daylight 

hours. Near surface flows are especially useful in explaining the transport and presence of the 

elevated ozone concentrations monitored aboard the MS Scotia Prince in the Gulf of Maine 

(Portland, Maine ferry to Yarmouth, Nova Scotia, Canada) . 

Other transport mechanisms, including boundary layer synoptic (upper level) flows and channeled 

(mid-level) nighttime flows are capable of transporting ozone and precursors as far as 600 km in a 

24-hour period and are responsible for longer range transport from the south and west (Blumenthal 

et al ., 1997). 

Residence time (or the time a pollutant stays in the air) analysis (Wishinski and Poirot, 1995) is a 

technique whereby the spatial characteristics of long-term trajectory climatology can be analyzed by 

keeping track of the residence time (in hours) for selected back trajectories . This was done for 

several New England sites during the summers from 1989 through 1995 . Back trajectories from 

Port Clyde, Maine show that for days on which Maine exceeds the ozone national ambient air 

quality standard (NAAQS), the wind is invariably from the south and west. These trajectories also 

show that the Northeastern Corridor is principally responsible for nonattainment in New Hampshire 

and Maine, with areas to the south and west of the Corridor having lesser, but still significant impacts. 

2.2 .3 .1 Sea Breeze 

The Atlantic Ocean produces changes in wind directions and wind speeds along the shoreline, 

especially in New England. While most inland areas experience regional wind patterns with only 

small variations due to terrain features and other frictional effects; coastal locations are far more 

variable. Sea breezes develop during the heating of the day when the ground heats up, warming the 

onshore air mass. This air mass then rises, causing cooler air near the surface to flow in from over 

the ocean (Figure 2-9). Sea breezes are actually a subset of the NARSTO-NE near-surface flows 

that are driven by temperature differences between land and water, which also affects changes in 

mixing heights . Daytime sea breezes flow from the relatively cool waters of the ocean towards the 

coast, and diminish over a short distance due to mixing with regional wind patterns persisting 

further inland and with diurnal mixing. 

Figure 2-9 - How the Sea Breeze Works 

Sun Heats 

the Earth 

SEABREEZE 

Low Pressure High Pressure 

Hot Air Rises (- Cool Onshore Breeze 

The sea breeze is developed 

through the temperature 

differences between the 

ground and the water. As the 

sun warms the ground, it 

begins a cycle by causing the 

air to rise . This air cools as it 

moves over the water, sinks 

and then blows back towards 

the shore. 
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Onshore breezes are the primary reason that high ozone concentrations occur along the New 

Hampshire coast, while substantially lower concentrations are recorded just a few miles farther 

inland . The afternoon sea breeze shifts the wind direction to the south and east, bringing ozone from 

over the ocean onshore. As documented by the NHDES and the Maine Department of Environmental 

Protection, these sea breezes develop suddenly and can drive ozone concentrations sharply upward. 

The offshore ozone blown in by sea breezes appears to originate from precursors emitted in the 

metropolitan Boston area. 

2.2 .3 .2 Offshore Transport 

Offshore, just beyond the strongest coastal sea breezes, larger scale wind fields develop that may 

differ in direction from the inland regional wind pattern. Lower mixing heights, differing 

temperature gradients, and lower frictional effects cause this differential . Off the New Hampshire 

and Maine coasts (Figure 2-10), it is not uncommon for the over-water wind field to come from the 

south, while the inland regional wind field is more from the southwest. This pattern allows transport 

of the ozone plume from the metropolitan Boston area to travel over the Gulf of Maine to the New 

Hampshire coast, even when inland wind observations suggest this should not be happening. 

The North Atlantic Regional Experiment (NARE) measured surface level ozone and precursor 

concentrations at both coastal and offshore locations in the Gulf of Maine during August and 

September of 1993 (Ray et al ., 1996). The researchers observed ozone plumes in the Gulf of Maine 

ranging in width from 55 to 93 km and extending the entire length of the New Hampshire and 

Maine coastlines . The timing of the observed peak ozone concentrations, the presence of elevated 

ozone levels only along the coast, and low NOx concentrations all suggest that urban plumes 

transported over the Gulf of Maine are brought inland by sea breezes to the coastal regions, and that 

regional control strategies will be needed to reduce ozone concentrations along the coast. 

Recent photochemical modeling utilizing the California Photochemical Grid Model (CALGRID) 

model (Earth Tech, 2006) serves to confirm the presence of an urban plume moving northeastward 

over the Gulf of Maine, where it is then carried by afternoon sea breezes to the coast. 

Along the New Hampshire and Maine coastlines, ozone levels have not been observed to exceed the 

NAAQS unless there is at least a moderate westerly to southwesterly wind at the surface. Typical 

ozone episodes are characterized by the concentration of transported ozone and precursors in the 

Gulf, of Maine during the morning and mid-day hours, with afternoon sea breezes bringing high 

concentrations of ozone ashore in the afternoon and evening. Monitored ozone concentration data 

and measured wind vectors show ozone exceedances in Maine and New Hampshire to be the direct 

result of a large mass of both ozone and unreacted precursors being transported into the Gulf of 

Maine from areas to the south and west. Here, precursors react and are then transported ashore, a 

conclusion supported by data collected by monitors on both the MS Scotia Prince (see Figure 2-10) 

in the Gulf of Maine and on land-based monitors that show significantly decreased levels of ozone 

at inland sites (AIRS) . 

Ozone air quality monitors within Maine and New Hampshire also confirm the presence and 

significance of transported ozone and its precursors . The ozone monitoring network in Maine 

extends along the coast from the photochemical assessment monitoring station (PAMS) located in 

Kittery, Maine (operated by the State of New Hampshire Department of Environmental Services) to 

as far north as Bar Harbor. Maximum ozone concentrations along the Maine coast almost always 

follow a sequential pattern, with the most southerly sites monitoring daily ozone maximums in the 
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mid to late afternoon, and downwind sites experiencing maximum readings later in the day and into 

the evening hours. 

Figure 2-10 - Offshore Ozone Measurements from the Scotia Prince 

The Scotia Prince ferry is a scheduled passenger and vehicle ferry that runs between Portland, Maine, and 

Yarmouth, Nova Scotia, Canada. This ferry has an ozone monitor that tracks air pollution levels during its 

journey between ports. The ferry often identifies distinct air pollution areas or plumes offshore over the Gulf 

of Maine. Source : MEDEP 

2.3 The Development of an Ozone Episode 

Since the late 1970s, a wealth of information has been collected concerning the regional nature of 

the Northeast's ground-level ozone air quality problem. Scientific studies have uncovered a rich 

complexity in the interaction of meteorology and topography with ozone formation and transport. 

The evolution of severe ozone episodes in the eastern U.S . often begins with the passage of a large 

high pressure area from the Midwest to the middle or southern Atlantic states, where it assimilates 

into and becomes an extension of the Atlantic (Bermuda) high pressure system (see example in 

Figure 2-11). During its passage east, the air mass accumulates air pollutants emitted by large coalfired power plants and other sources located outside the region . These expansive weather systems 

favor the formation of ozone by creating a vast area of clear skies and high temperatures . These two 

prerequisites for abundant ozone formation- are further compounded by a circulation pattern 

favorable for pollution transport over large distances. In the worst cases, the high pressure systems 

stall over the eastern United States for days, creating ozone episodes of strong intensity and long 

duration . 
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Figure 2-11 - Bermuda High Synoptic Scale Transport 

'[ Plymouth State Weather Center .'X 

Surface Winds (mfs) WXP flrldysis for l8Z 4 JUL 99 

Sea L-vel Pressure ti mb} __ 11fXP ardysis for 13Z 4 JUL <J9 

100010021074100610ClB 1310 1012 17U 1016 10181=0=1021 1026 LO= 1001.7 Ht 1025.3 

With the knowledge of the different transport scales into and within the region, a conceptual picture 

of bad ozone days emerges. After sunset, the ground cools faster than the air above it, creating a 

nocturnal temperature inversion. This stable boundary layer extends from the ground to only a few 

hundred meters in altitude . Above this layer, a nocturnal low level jet can form with higher velocity 

winds relative to the surrounding air. It forms from the fairly abrupt removal of frictional forces 

induced by the ground that would otherwise slow the wind. Absent this friction, winds at this height 

are free to accelerate, forming the nocturnal low level jet. Ozone above the stable nocturnal 

inversion layer is likewise cut off from the ground, and thus it is not subject to removal on surfaces 

or chemical destruction from low level emissions. Ozone in high concentrations can be entrained in 

the nocturnal low level jet and transported several hundred kilometers downwind overnight. The 

next morning as the sun heats the Earth's surface, the nocturnal boundary layer begins to break up, 

and the ozone transported overnight mixes down to the surface where concentrations rise rapidly, 

partly from mixing and partly from ozone generated locally. By the afternoon, abundant sunshine 

combined with warm temperatures promotes additional photochemical production of ozone from 

local emissions . As a result, ozone concentrations reach their maximum levels through the 

combined effects of local and transported pollution. 

Ozone moving over water is, like ozone aloft, isolated from destructive forces . When ozone gets 

transported into coastal regions by bay, lake, and sea breezes arising from afternoon temperature 

contrasts between the land and water, it can arrive highly concentrated . 
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During severe ozone episodes associated with high pressure systems, these multiple transport 

features are embedded within a large ozone reservoir arriving from source regions to the south and 

west of the OTR. Thus a severe ozone episode can contain elements of long range air pollution 

transport from outside the Northeast, regional scale transport within the OTR from channeled flows 

in nocturnal low level jets, and local transport along coastal shores due to bay, lake, and sea breezes. 

The recognition that ground-level ozone in the eastern United States is a regional problem requiring 

a regional solution marks one of the greatest advances in air quality management in the United 

States . During the 1990s, air quality planners began developing and implementing coordinated 

regional and local control strategies for NOx and VOC emissions that went beyond the previous 

emphasis on urban-only measures. These measures have resulted in significant improvements in air 

quality across the OTR. Measured NOx emissions and ambient concentrations have dropped 

between 1997 and 2005, and the frequency and magnitude of ozone exceedances have declined 

within the OTR. 

2.4 NOx vs. VOC Control Strategies Effectiveness 

The effectiveness of a NOx-focused or VOC-focused control strategy to reduce ozone is not 

constant by location; rather, it is a changing chemical characteristic of an air parcel affecting a 

particular location. As a result, the effectiveness of a NOx or VOC-focused control strategy can 

vary within an air parcel as it dynamically evolves over time with transport, dispersion, and 

photochemical aging (NARSTO, 2000). 

On a regional basis, OTAG (Ozone Transport Assessment Group), Clean Air Interstate Rule 

(CAIR), and other modeling studies have consistently shown that NOx reductions have the greatest 

impact on regional ozone concentrations, while VOC reductions have more local impacts. This is 

largely a result of significant naturally occurring VOC emissions (especially isoprene) in large 

forested regions of the eastern U.S. Real-world results from regional NOx reductions at power 

plants (i .e ., the NOx SIP Call) are now indicating that significant ozone reductions are occurring on 

a regional basis as a result of regional NOx strategies . 

As a general rule, VOC reductions may be effective at reducing urban-scale ozone pollution in lieu 

of or in combination with local NOx reductions, while regional NOx controls are most effective at 

reducing regional ozone. While a general approach can be outlined in evaluating the potential 

effectiveness of NOx and VOC-focused control strategies, the optimal strategy for a specific 

location will depend on the particular circumstances of that location. Exceptions to a VOC-only 

strategy for an urban area can occur when the urban area has large natural VOC emissions, ozone is 

transported from upwind, or there is recirculation of aged local pollution (e.g ., sea breeze effect). 

Furthermore, because the conditions causing individual ozone episodes can vary, a given urban area 

may change in sensitivity between a NOx and VOC-focused strategy depending on a particular 

episode's conditions (NARSTO, 2000). Therefore, the appropriate combination of NOx and VOC 

controls at the local level depends on local circumstances with the realization that a single approach 

focusing on NOx- or VOC-only controls is not necessarily effective for all episode types. It is clear, 

however, that regional NOx reductions provide regional ozone reductions, and this will influence 

ozone levels being transported into local urban areas. Thus, the most effective controls for New 

Hampshire are NOx based regional controls with local NOx and VOC based controls. 
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3. ATTAINMENT MODELING 

Air quality modeling to demonstrate New Hampshire's attainment of the 8-hour ozone standard uses 

a regional photochemical modeling platform capable of estimating the distribution and magnitude of 

air pollutant concentrations within a reasonable range of error. Base-year and projected future year 

emissions inventories are used as input into the air quality model. Emission reduction strategies are 

applied as needed. . The results of the air quality modeling are applied in a relative sense by 

calculating the percent ratio of the future year modeling results (which reflect the emissions 

reduction strategies) to the base-year modeling results. This ratio is then applied to the observed 

base year design value to obtain a corresponding estimated future year design value. Known as the 

relative reduction factor (RRF) technique, this method follows EPA guidance; for further 

description see Section 3.1 .5 . 

3.1 Modeling Methodology 

For the 8-hour ozone analyses, New Hampshire relied on the regional photochemical air quality 

modeling that was conducted by the New York State Department of Environmental Conservation 

(NYSDEC) and other modeling centers on the Community Multiscale Air Quality (CMAQ 

modeling platform. In addition, New Hampshire and other states used the California Photochemical 

Grid Model (CALGRID) screening-level modeling platform to evaluate additional emissions control 

scenarios and perform sensitivity runs. The general methodologies that were used in running both 

of these modeling platforms for the evaluation of 8-hour ozone are described in the sections below. 

3.1 .1 Identification of Models and Domain Used 

The SIP-quality modeling that was done for the 8-hour ozone analyses was performed on the 

CMAQ modeling platform. Additional modeling was done on the CALGRID screening-level 

platform. The CMAQ and CALGRID platforms were run on the same modeling domain using a 

common set of model inputs . Specifically, the OTC ozone modeling domain was set up on a 

Lambert Conic Conformal projection and covers the eastern United States and parts of Canada. The 

southwest corner of the domain was set at 264 km, -888 km and the northeast corner was set to 2328 

km, 1176 km. A 12-km grid cell resolution was used with 172 grid cells in the east-west direction 

and 172 grid cells in the north-south direction. For the vertical grid definition, 22 layers were used 

in the CMAQ simulations . For CALGRID, processing programs were used to reformat the 

boundary conditions, meteorology, and emissions; these mapped the 22 layers used for CMAQ to a 

total of nine vertical layers for the CALGRID modeling. The OTC CMAQ/CALGRID modeling 

domain is shown in Figure 3-l . The OTC 12-km ozone modeling domain is a subset of the 36-km 

national domain which was used by the Regional Planning Organizations (RPOs) for regional haze 

analysis. The 36-km national grid is shown in Figure 3-2 . 

For the CMAQ modeling, boundary conditions were derived from GEOS-Chem (Goddard Earth 

Observing System) global atmospheric simulations by running CMAQ on the 36-km continental 

grid. For the CALGRID platform, initial conditions, side boundary conditions, and top layer 

concentrations were derived from the CMAQ boundary conditions files by means of a processing 

program. This program mapped the 22 vertical layers used in the CMAQ simulations to the nine 

layers used with CALGRID. It produced the necessary side boundary file and top layer 

concentration file for each modeled episode day. It also produced an initial conditions file for each 

episode day processed; these files could be retained so that the CALGRID user could begin a 
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simulation on any desired episode day. It should be noted that the default option of using 2002 

boundary conditions was employed for all of the base case and future year CMAQ and CALGRID 

simulations. 

Further details regarding the technical options used in the CMAQ simulations are available in 

NYSDEC's. technical support document TSD-ld, 8hr Ozone Modeling using the SMOKE/CMAQ 

system, February 1, 2006. Additional information on the CALGRID modeling platform can be 

found in NHDES' Modeling Protocol for the OTC CALGRID Screening-Level Modeling Platform 

for the Evaluation of Ozone, May 23, 2007. 

Figure 3-1 - Map of the CMAQ/CALGRID Modeling Domain 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 17 

Figure 3-2 - Map of the RPO National Domain 

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3.1 .2 Emissions Processing Methodology 

The base year and future year emissions inventories that were used in the regional photochemical air 

quality modeling for the 8-hour ozone analyses were prepared by the RPOs and their contractors. 

These inventories were processed for input into the CMAQ air quality model using the Sparse 

Matrix Operator Kernel Emissions (SMOKE) model. The SMOKE modeling was performed by 

NYSDEC and other modeling centers, including NESCAUM and the Virginia Department of 

Environmental Quality (VADEQ). Emissions processing was done for the 2002 Base Year and 

2009 On The Books/On The Way (OTB/OTW) modeling scenario . The OTB/OTW scenario 

accounted for those emissions control measures that were either on the books or reasonably 

anticipated to occur. The 2002 Base Year and 2009 OTB/OTW emissions are summarized by state 

in Table 3-1 . Further details on the SMOKE processing that was done in support of the 8-hour 

ozone analyses are provided in NYSDEC's technical support document TSD-lc, Emission 

Processing for the Revised 2002 OTC Regional and Urban 12 km Base Case Simulations, 

September 19, 2006 . 
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Table 3-1 - Modeling Emissions Inventory: State-by-State Anthropogenic NOx 

State 

2002 

Baseline 

(tons/day) 

2009 

OTW/OTB 

(tons/day) 

Percent Reduction 

from 2002 Baseline 

Connecticut 232 .16 149.41 35 .64% 

Delaware 101 .20 91 .53 9.56% 

D.C . 29.13 18.30 37 .18% 

Maine 170.64 109.75 35.68% 

Maryland 548 .58 312 .77 42.99% 

Massachusetts 483 .18 312 .68 35.29% 

New Hampshire 131 .02 84.22 35.72% 

New Jersey 625 .68 397 .32 36.50% 

New York 1199.32 831 .85 30.64% 

Pennsylvania 1614.24 1020.05 36.81% 

Rhode Island 89.78 57 .60 35.84% 

Vermont 54.44 34 .62 36.41% 

Virginia 975.74 673.39 30.99% 

Alabama 732.86 492 .41 32.81% 

Arkansas 519.30 268.22 48.35% 

Georgia 1153 .90 874.75 24.19% 

Kentucky 1043 .23 641 .29 38.53% 

Illinois 1797.25 1067.17 40.62% 

Indiana 1329.23 926.42 30.30% 

Michigan 902.07 812.06 9.98% 

Mississippi 356.48 271 .04 23 .97% 

Missouri 733 .00 438.76 40.14% 

North Carolina 1141 .21 744.30 34.78% 

Ohio 1379.28 848.93 38 .45% 

South Carolina 660.35 481 .35 27.11% 

Tennessee 1045 .52 710.79 32.02% 

West Virginia 902.95 432.65 52.08% 

I Wisconsin ~ 667.49 ~ 447.50 ~ 32 .96% 

For the CALGRID modeling effort, the pre-merged SMOKE emissions files were obtained from the 

modeling centers and re-formatted for input into EMSPROC, the emissions pre-processor for the 

CALGRID modeling system. EMSPROC allows the CALGRID user to adjust emissions 

temporally, geographically, and by emissions category for control strategy analysis. The pre-merged 

SMOKE files that were obtained from the modeling centers were broken down into the biogenic, 

point, area, non-road, and on-road emissions categories. These files by component were then 

converted for use with EMSPROC, thus giving CALGRID users the flexibility to analyze a wide 

variety of emissions control strategies. QA/QC plots were generated during the re-formatting of the 

emissions data to ensure that an accurate modeling inventory was generated for the CALGRID 

platform. Example emissions QA/QC plots are shown in Figures 3-3 through 3-6. 
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Figure 3-3 - QA/QC Plot of Surface Source CO Emissions 

CO Bmlsriom: {4ou per Sq Mile ) a the CLLM 2.45 Nadding Domain 

UPD11$D 2002 Ban 

Haur 18 on July 29, 2002 

SON 

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0 .0e 

3 .07 

0 .0s 

0.05 

:. 0.04 

0.03 

0.02 

0.01 

0 

Figure 3-4 - QA/QC Plot of Surface Source VOC Emissions 

8urfae WC Emissions (faoA per 3q L{ile) on the CALCRiD 2.4b Modeliq Domain 

UPD118D TA02 Baee 

soM 

48N 

48N 

44H 

42N 

40N 

98N 

869 

94u 

32N 

Haar 18 on July 29, 2002 

gas DOW 87F 84W 81W 98W 75i 42Y 69W 

0.4 

0.2 

0.15 

0.1 

0.09 

0.08 

0.07 

0.00 

0.05 

0.04 

0.03 

0.025 

0.02 

1 ').015 

0.01 

0,008 

a.o03 

0.002 

0 
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Figure 3-5 - QA/QC Plot of Point Source NOx Emissions 

Polnt Souee HOx gmLafons Nns' on the CILQBID 2.45 Hadelia` Domain 

UPDL'fBD OM Due Cue 

H4ur 14 on July 19, 2002 

B3W BOW B7R BdY all 7mP 751 7ZW on 

18 

14 

12 

10 

8 

8 

4 

2 

1 

0.8 

~ 0.8 

0.4 

0.2 

;a 0 .18 

~ 0.18 

0.14 

0 .12 

0.1 

0 

Figure 3-6 - QA/QC Plot of Point Source S02 Emissions 

Point Sauce 902 BmissLoea (tons) on the CLI.CRD3 2.45 MAW Domain 

UPDI'lED 2002 One Cax 

Hour 19 on July 19, 2002 

4 

2 

1 

0.9 

'l.8 

J .7 

0 .8 

0 .5 

OA 

0 .3 

a.z 

9.1 

a 

BaW MW am MW all 7e® 7sia zBW am 
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3.1 .3 Meteorology Processing Methodology 

The meteorological modeling that was done for the CMAQ platform was performed by the 

University of Maryland (UMD) in conjunction with staff at NYSDEC. UMD used the Penn 

State/National Center for Atmospheric Research (NCAR) 5th Generation Mesoscale Model (MM5) 

Version 3.6 to generate year 2002 meteorological inputs . The MM5 modeling domain was set up on 

a two-way nested grid that followed the RPO national domain. The 36-km coarse mesh grid 

consisted of 149 grid cells in the east-west direction and 129 grid cells in the north-south direction. 

The 12-km fine mesh grid consisted of 175 grid cells in both the east-west and north-south 

directions . A total of 29 vertical layers were used in the MM5 simulations. An extensive analysis 

was undertaken to compare the MM5 predictions with observations for the period of May through 

September 2002. An assessment was made to compare MM5 outputs with surface observations 

from the National Weather Service and CASTNet, wind-profiler measurements from the 

Cooperative Agency Profilers (CAP) network, satellite cloud image data from the UMD Department 

of Atmospheric and Oceanic Science, and precipitation data from the Earth Observing Laboratory at 

NCAR. Technical details regarding the 2002 MM5 simulations and the assessment to compare 

them with observations are described in NYSDEC's Technical Support Document TSD-la, 

Meteorological Modeling Using Penn State/NCAR 5th Generation Mesoscale Model (MM5), 

February 1, 2006 . 

For the CALGRID modeling platform, a processing program was used to interpolate the MM5 

outputs to the CALGRID modeling grid and map them to CALGRID's vertical layer structure. 

QA/QC plots were generated during the processing to ensure the accuracy of the interpolated data. 

Figures 3-7 through 3-9 show example QA/QC plots from the re-formatting of the meteorological 

data for use with the CALGRID modeling platform. 

Figure 3-7 - QA/QC Plot of Humidity Data 

August 6, 2002 Hour 12 

Humidity Layer 1 

CALGRID 2.45 Modeling Domain 

c 0 

z 

U 

U 

J 

400 600 800 1000 1200 1400 1600 1800 2000 2200 

Humidity (ppm) 

soooo 

28000 

26000 

24000 

22000 

20000 

18000 

16000 

14000 

12000 

10000 

8000 

000 

4000 

2000 

0 

NHDES 

7/18/O6 

LCC Easting (km) 
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Figure 3-8 - QA/QC Plot of Temperature Data 

August 6, 2002 Hour 18 

Temperature Layer 1 

CALGRID 2.45 Modeling Domain 

400 600 800 1000 1200 1400 1600 1800 2000 2200 

LCC Easting (km) 

Figure 3-9 - QA/QC Plot of Rainfall Data 

August 12, 2002 Hour 17 

Rain 

CALGRID 2.45 Modeling Domain 

Temp (K) 

' 310 

306 

306 

302 

300 

1 

304 

298 

296 

294 

292 

290 

2865 

284 

282 

280 

0 

NHDES 

7/23106 

Rain (inches) 

1.5 

1.4 

1.3 

1.2 

1.1 

1.0 

09 

0.8 

0.7 

0.6 

~ 0.5 

i 

_ , ~ 0.4 

03 

02 

01 

00 

NHDES 

7/17/O6 

LCC Easting (km) 
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3.1 .4 Model Testing 

NYSDEC did an extensive quantitative analysis to evaluate predicted concentrations of ozone, as 

well as other gaseous and aerosol pollutants, against 2002 observations . This work is described in 

their technical support document TSD-le, CMAQ Model Performance and Assessment, 8-Hr OTC 

Ozone Modeling, February 23, 2006: The authors used a wide variety of statistical metrics to assess 

the correlation of model predictions and observations, including: 

. 

. 

. 

Correlation coefficient 

Normalized mean error 

Root mean square error 

Fractional error 

Mean absolute gross error 

Mean normalized gross error 

Mean bias 

Mean normalized bias 

Mean fractionalized bias 

Normalized mean bias 

NYSDEC also evaluated the diurnal patterns for those pollutant species that are reported hourly . 

With respect to 8-hour ozone, NYSDEC's model performance evaluation showed that the CMAQ 

model performed reasonably and that it adequately reproduced the pattern of observations, 

especially in urban areas and along the northeast corridor. Their analysis showed some model 

under-prediction during the mid-August period . Their analysis also showed that the diurnal 

predictions for ozone tracked fairly well with observations . Detailed tables and figures illustrating 

the CMAQ modeling platform's performance evaluation are shown in NYSDEC's technical support 

document TSD-le. 

NHDES performed a qualitative and quantitative assessment of the CALGRID screening platform's 

ability to reproduce observed ozone concentrations . To assess its performance, the CALGRID 

screening platform was run for the 2002 Base Case for the July 31 to August 16, 2002 modeling 

episode. Predicted maximum 8-hour ozone concentrations at monitor locations were compared 

against observations for 2002. Figure 3-10 shows the relative bias between maximum 8-hour ozone 

observations and predicted CALGRID 8-hour ozone concentrations for the 2002 Base Case for the 

episode from July 30 through August 12 . Figure 3-11 shows a plot of predicted 2002 Base Case 

ozone concentrations against 2002 observations for an example episode day. Although the 

CALGRID model has a tendency to over-predict, especially in the urban core areas of northern 

Virginia, Maryland, southeastern Pennsylvania, New York City and Boston, it does a reasonable job 

of reproducing the pattern of the 2002 maximum ozone observations . 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 24 

Figure 3-10 - Relative Bias between Maximum 8-Hour Ozone Concentrations Predicted with 

CALGRID and Observed Values 

Relative Bias (CALGRID minus Observed) 

Based on Model Data for 

July 30 - August 12, 2002 

2002 Base Case Emissions 

versus Observed Data 

Green Circles are where 

CALGRID Underpredicts 

Red Triangles are where 

CALGRID Overpredicts 

NHDES 11/21/06 

Figure 3-11 - Comparison of Modeled Maximum 8-Hour Ozone Concentrations 

for August 13, 2002 

Maamnmn8-Hour 0loone Conce~aobons Maximum 8-Hour Ozone Concentrations 

Gbanvatioms - 2002 Base Case CALGRID - 2002 Base Case 

OTC M odebmg Doanain - August 13, 2002 OTC Modeling Domain - August 13, 2002 

Ozone 

Concentrations 

(PPB) 

--

A V; 

0 to 40 

40 to 50 

50 to 60 

60 to 70 

70 to 80 

80 to 90 

90 to 100 

100 to 150 

NHDES 

11/27/O6 
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3.1 .5 Establishing Estimates of Future Design Values 

In accordance with EPA guidance, future design values for regional modeling were estimated using 

the relative reduction factor (RRF) technique. This technique uses a statistically valid number of 

before-and-after modeling results for each monitoring location to calculate the RRF. Briefly, RRFs 

were calculated from the average strategy model predicted concentration divided by the average 

base model predicted concentration for the same grid cell location. This calculation was performed 

for the full ozone season (for CMAQ. A shorter, but representative period of time was used in 

some CALGRID modeling cases after proving to provide valid estimates based on comparisons to 

similar modeling for the full ozone period. In most cases, the RRF is less than 1 .0, indicating that 

the emission control strategy lowers the future design value. In order to relate model predictions to 

monitored values, the grid cells and actual monitor geographic locations must be paired . This was 

performed according to EPA guidance by using the maximum value of the block of the nearest 9 

grid cells to each monitor location as it is overlaid on the modeling grid. The resulting RRF is then 

multiplied by the corresponding base 3-cycle (2000-2002, 2001-2003, 2002-2004) average design 

value for each monitor to calculate an estimated future year design value for comparison to the 

NAAQS. 

3.2 CMAQ and CALGRID Modeling Results 

Statistical summaries of peak 8-hour ozone concentration for each CMAQ and CALGRID model 

run are provided below in Tables 3-2 and 3-3 . These results reflect the July 31 to August 16, 2002, 

modeling episode (the model was run for July 30 to August 16, but July 30 is considered to be a 

model warm-up day). Included in the summary tables are peak modeled ozone concentrations for 

five New Hampshire monitoring locations that routinely record elevated ozone levels (Keene, 

Manchester, Nashua, Portsmouth and Rye) and a more general statistic, "Grid Cell Hours" (Table 

3-3), providing a dynamic domain-wide response to emission reductions . Model predicted ozone 

concentrations at the five New Hampshire locations are averages of a 9-grid cell area surrounding 

each of the monitor locations (note that these are the absolute model-predicted concentrations and 

not the RRF-processed estimated future year design values used to determine future attainment -

these values can be found in Table 3-4 below) . 

In all, there are 29,584 grid cells in the modeling domain (172 x 172) . "Grid Cell Hours" is a count 

of the number of grid cells exceeding the indicated thresholds (80 ppb, 100 ppb, and 120 ppb) in a 

given hour. This value is presented in order to show the depth of ozone exposure and how it 

improves under various emission reduction strategies. The maximum grid cell hour count possible 

is 710,016 for the full domain over a 24-hour day (172 x 172 x 24), although due to nighttime hours 

and geographically distinct areas within the domain, maximum expected Grid Cell Hour counts is 

about 400,000. 

Table 3-2 - CMAQ Maximum Modeling Statistics for 2002 Base and 2009 OTB/OTW 

CMAQ Run 

Peak 8-Hour Ozone Concentration (ppb) 

Keene Manchester Nashua Portsmouth Rye 

2002 Base Case 85 79 87 133 133 

2009 OTW/OTB 73 68 74 114 114 
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Table 3-3 - CALGRID Maximum Modeling Statistics for 2002 Base, 2009 OTB/OTW, 

and 2009 Sensitivity Runs 

Peak 8-Hour Ozone Concentration (ppb) Gri d Cell Hours CALGRID R un 

Keene Manchester Nashua Portsmouth Rye >70ppb >85ppb >100ppb 

2002 Base Case 89 100 102 130 130 86,751 30,576 8,266 

2009 OTW/OTB 79 92 93 124 124 56,234 15,444 3,447 

2009 NH Zero-Out 77 85 95 119 119 55,686 15,307 3,441 

2009 90% NOx 

Reduction 42 49 47 62 62 40 0 0 

2009 90% VOC 

Reduction 79 93 94 120 120 55,643 15,540 3,325 

Note: Grid cell hours are based on the full modeling domain. 

Table 3-4 summarizes the modeling results for New Hampshire by listing current design values and 

2009 modeled design values for all monitors in the state. 

Table 3-4 - Modeling Summary for New Hampshire Monitors 

8-hour Ozone Design Values (ppb) 

Current Predicted Desig n Value (DVF) 

AIRS ID Name Design Value 

(DVC) 

2009 

OTB/OTW 

CMA 

2009 

OTB/OTW 

CALGRID 

330012004 Laconia 76.5 nc 66 

330031002 Conway 67 nc 61 

330050007 Keene 74.3 64 68 

330090008 Haverhill 70.3 nc 64 

330110020 Manchester 75 .5 na 70 

330111010 Nashua 86 74 80 

330115001 Peterborough 84 73 73 

330130007 Concord 74.7 nc 66 

330150012 Rye 83 .5 72 78 

330150013 Brentwood 80 68 72 

330150015 Portsmouth 68 59 63 

330173002 Rochester 78 .5 67 73 

330190003 I Claremont 74 .3 nc 67 

Notes: 

1 . "nc" indicates that a future design value was not calculated because of the limitation of the 

relative reduction factor (RRF) methodology. 

2. The Manchester monitor was not included in the CMAQ results; this is indicated by "na" in 

the table. 
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The figures below show the geographical distribution of 8-hour ozone design values for the 2002 

Base Case and 2009 OTB/OTW scenario for ozone monitor locations in the Ozone Transport 

Region. Figure 3-12 displays the CMAQ-predicted 2009 design values versus the actual 2002 

design values . For comparison, Figure 3-13 shows CALGRID-predicted design values for the 2009 

OTB/OTW scenario . 

Figure 3-12 - CMAQ SIP-Quality Modeling Results for 2009 OTB/OTW vs. 2002 Design Values 

OTR Domain 

72 77 82 87 92 97 

Figure 3-13 - Plot of 2009 Estimated Design Values for the OTC 2009 OTB/OTW Strategy 

EPISODES 

July 7 - 23, 2002 

July 31 -August 16, 2002 

DESIGN VALUES 

(Revised 2/23107) 

Average of 2000-2002, 

2001-2003,2002-2004 

RRFTHRESHOLDS 

86 PPB, 70 PPB 

EMISSIONS BASE 

2002 Base 
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Figure 3-14 shows the CALGRID-modeled differences (improvements) in the maximum 8-hour 

ozone concentration between the 2009 OTB/OTW scenario and the 2002 base case. 

Figure 3-14 - Plot of Differences in Predicted Maximum 8-Hour Ozone Concentrations 

between 2002 Base Case and the OTC 2009 OTB/OTW Strategy 

17 

16 

15 

14 

13 

12 

11 

10 

9 

80 

70 

60 

50 

40 

30 

20 

10 

0 

0 10 20 30 40 50 60 70 80 90 100110120130140150160170 

Ozone 

Concentrations 

I 

_1 

40 

30 

25 

20 

15 

Note : 

10 

A positive 

5 number 

3 denotes a 

decrease in 

1 ozone conc . 

'i--{ -1 

-5 

-10 

-20 

-30 

NHDES 6/29/07 

CALGRID 2.45 

Modeling Domain 

After completion of the model runs, NHDES discovered that the 2009 on-road emission estimates 

for New Hampshire that were inputs to the modeling had been understated (by about 10% for VOC 

and 15% for NOx). To evaluate the uncertainty introduced by this situation, NHDES performed 

sensitivity modeling with CALGRID in which all New Hampshire on-road OTW/OTB NOx and 

VOC emission inputs were boosted by 25% for the July 31 to August 16, 2002, high ozone event. 

The results of this analysis showed that the adjusted inputs would have negligible effect on the 

modeled 8-hour design ozone values . 

3.3 EPA's CAIR Modeling 

On May 12, 2005, EPA promulgated the Clean Air Interstate Rule (CAIR). Under CAIR, 28 states 

across the eastern United States and the District of Columbia are expected to make reductions in 

NOx and S02 emissions. EPA performed technical analyses in support of CAIR, including air 

quality modeling to evaluate ambient levels of ozone and PM2,5. The CAIR modeling is described 

in EPA's Technical Support Document for the Final Clean Air Interstate Rule, Air Quality 

Modeling, March 2005 . The air quality modeling for ozone was performed with the Comprehensive 

Air Quality Model with Extensions (CAMx) version 3 .10 on a modeling domain covering much of 

the eastern United States . Three summer 1995 meteorological episodes were used in the modeling. 

The analysis years and emissions scenarios that were assessed included: 

" 2001 Base Year . 2010 CAIR Controls . 2015 BART Only 

" 2010 Base Case . 2015 CAIR Controls 

" 2015 Base Case 0 2015 CAIR + BART 
TSD for Redesignation of the Boston-Manchester-Portsmouth (SE), NH Nonattainment Area Page 29 

The 2010 and 2015 Base Cases reflect expected economic growth and the anticipated benefits 

associated with existing emissions control programs. 

The CAMx model predictions were used in a relative manner. Weighted-average 1999-2003 design 

values were applied as the basis of the observed 8-hour ozone concentrations . Using this 

methodology, EPA estimated maximum 8-hour ozone design values for each future-year scenario 

for each county in the modeling domain with an ozone monitor. Table 3-5 lists the maximum 

estimated future 8-hour design values for New Hampshire. These results show that, even without 

the emissions benefits associated with CAIR, all New Hampshire counties were predicted to be in 

attainment for 8-hour ozone for the 2010 and 2015 analysis years . 

Table 3-5 - CAIR Modeling Results for New Hampshire for 8-hour Ozone (ppb) 

1999-2003 Average Estimated Maximum 8-hour Future Design Value 

County Design Value 2010 Base 2010 CAIR 2015 Base 2015 CAIR 

Belknap 78.0 68 .5 68.2 65 .8 65 .0 

Carroll 66.5 60.3 60.0 58.6 58 .0 

Cheshire 73 .7 65 .2 64.9 63 .1 62 .0 

Hillsborough 85 .0 76.7 76 .6 74 .1 73 .9 

Merrimack 73 .0 64.8 64 .6 62 .3 61 .8 

Rockingham 82.7 75 .2 75 .1 73 .3 72.9 

Strafford 77.3 69.2 69 .1 66.8 66.5 

Note: Data taken from Appendix E of EPA's Technical Support Document for the Final Clean Air Interstate Rule, 

Air Quality Modeling, March 2005. 

References 

1 . Blumenthal, D.L ., F. Lurmann, N. Kumar., T. Dye, S . Ray, M. Korc, R. Londergan, and G. 

Moore. Transport and mixing phenomena related to ozone exceedances in the northeast U.S. 

EPRI Report TR-109523, Electric Power Research Institute, Palo Alto, CA, 1997 . 

2 . Clarke, J.F ., and J.K.S. Ching. "Aircraft observations of regional transport of ozone in the 

northeastern United States ." Atmos. Envt. 17, 1703-1712, 1983. 

3 . Earth Tech, Inc. Calgrid User Instructions. November 2006. 

4 . NARSTO . An Assessment of Tropospheric Ozone Pollution. NARSTO, July 2000. 

5 . Ray, J ., R. Heavner, M. Flores, and C. Michaelson . "Surface Level Measurements of Ozone and 

Precursors at Coastal and Offshore Locations in the Gulf of Maine." J. Geophys. Res. 101 

(D22), 29005-29011, 1996. 

6. Wishinski, P. and R. Poirot. Air Trajectory Residence Time Analysis Investigation of Ozone 

Transport Pathways: 1989-95. 1995 . 

7. Zhang J. and S.T. Rao. "The role of vertical mixing in the temporal evolution of groundlevel 

ozone concentrations ." J. Applied Meteor. 38, 1674-1691, 1999 .