# Modeling Protocol for the OTC CALGRID

Screening-Level Modeling Platform for the

Evaluation of Ozone

May 23, 2007

New Hampshire Department of Environmental Services

Air Resources Division 29 Hazen Drive Concord, NH 033021

1.0 Introduction

The Ozone Transport Commission (OTC) has sponsored the development of a photochemical modeling system to assist states in t he preparation of their State Implementation Plans (SIPs) for attaining the eight -hour National Ambient Air Quality Standard (NAAQS) for ozone. The Community Multisca le Air Quality Model (CMAQ) is the basis of the OTC SIP-quality modeling platfo rm that is being used in states’ eighthour ozone attainment SIPs.

Running the CMAQ modeling platform is very resource intensive and usually requires the use of a Unix-based operating system. Therefor e, the CMAQ modeling that is being done in support of the eight-hour ozone SIPs is lim ited to a handful of modeling centers that have the necessary expertise and computer reso urces. Similarly, because of the substantial effort, time, and storage space require d to run the SIP-quality CMAQ platform, it is impractical to assess a large numbe r of run scenarios.

Consequently, OTC sponsored the development of an a dditional grid-based photochemical modeling platform that states could u se as a screening tool for running additional emissions control strategies or performi ng sensitivity runs. The requirements for this additional modeling platform were that it be flexible, portable, and easily accessible to agencies that wish to use it. In thi s manner, a larger number of run scenarios could be modeled, allowing states to scre en a wider variety of potential control strategies.

The California Grid Model (CALGRID) was selected as the basis of this screening platform. CALGRID is a grid-based photochemical mo deling platform that is designed to be run in a Windows environment. CALGRID has re cently undergone a series of improvements and enhancements, with the most recent version being designated CALGRID Version 2.45. CALGRID Version 2.45 is bein g used as the screening platform for the OTC eight-hour ozone attainment SI Ps. This document outlines the manner in which CALGRID will be used in these effor ts.

2.0 Platform Description and Model Inputs

To make the CALGRID modeling platform the best poss ible tool to supplement the SIPquality CMAQ platform, it was decided that CALGRID would be run on the same modeling domain using a common set of model inputs. All boundary conditions, meteorology, and emissions inputs were the same as those used for the SIP-quality CMAQ platform. Processing programs were written to convert these inputs into a format useable by the CALGRID model. The modeling domain and model inputs are described in the sections below.

2.1 Modeling Domain

The OTC CMAQ/CALGRID modeling domain was set up on a Lambert Conic Conformal projection and covers the eastern United States and parts of Canada. The2

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 resolut ion was used with 172 grid cells in the east-west direction and 172 grid cells in the n orth-south direction. For the vertical grid definition, 22 layers were used in the CMAQ si mulations. For CALGRID, the processing programs that were used to reformat the boundary conditions, meteorology, and emissions mapped the 22 layers used for CMAQ to a total of nine vertical layers for the CALGRID modeling. The OTC CMAQ/CALGRID modelin g domain is shown in Figure 1.

Figure 1: Map of the OTC CMAQ/CALGRID Modeling Doma in



## 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160

2.2 Boundary Conditions

For the OTC CMAQ modeling, boundary conditions were derived from GEOS-Chem (Goddard Earth Observing System) global atmospheric simulations by running CMAQ3

on the 36-km continental grid. For the CALGRID pla tform, initial conditions, side boundary conditions, and top layer concentrations w ere 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 to p layer concentration file for each modeled episode day. It also produced an initial c onditions file for each episode day processed; these files could be retained so that th e user could begin a CALGRID simulation on any desired episode day.

2.3 Meteorology

The meteorological modeling that was done in suppor t of the OTC CMAQ SIP-quality modeling platform was performed by the University o f Maryland (UMD) in conjunction with staff at the New York State Department of Envi ronmental Conservation (NYSDEC). UMD used the Penn State/National Center for Atmosph eric Research 5 th Generation Mesoscale Model (MM5) Version 3.6 to generate year 2002 meteorological inputs. The details of this work are described in NYSDEC’s Tech nical Support Document TSD-1a, Meteorological Modeling Using Penn State/NCAR 5 th Generation Mesoscale Model (MM5), February 1, 2006. For the CALGRID modeling platform, a processing p rogram was used to interpolate the MM5 outputs to the CALG RID 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 interpolat ed data. Figures 2 through 4 show example QA/QC plots from the re-formatting of the m eteorological data.

Figure 2: QA/QC Plot of Humidity Data

August 6, 2002 Hour 12 Humidity Layer 1 CALGRID 2.45 Modeling Domain

Humidity (ppm)

NHDES 7/18/06

400 600 800 1000 1200 1400 1600 1800 2000 2200 LCC Easting (km) -800 -600 -400 -200 0 200 400 600 800 1000LCC Northing (km)

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 26000 28000 300004

Figure 3: QA/QC Plot of Temperature Data

August 6, 2002 Hour 18 Temperature Layer 1 CALGRID 2.45 Modeling Domain

Temp (K)

NHDES 7/23/06

400 600 800 1000 1200 1400 1600 1800 2000 2200 LCC Easting (km) -800 -600 -400 -200 0 200 400 600 800 1000LCC Northing (km)

0 280 282 284 286 290 292 294 296 298 300 302 304 306 308 310

Figure 4: QA/QC Plot of Rainfall Data

August 12, 2002 Hour 17

Rain CALGRID 2.45 Modeling Domain

Rain (inches)

NHDES 7/17/06

400 600 800 1000 1200 1400 1600 1800 2000 2200 LCC Easting (km) -800 -600 -400 -200 0 200 400 600 800 1000LCC Northing (km)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.55 2.4 Emissions

The Regional Planning Organizations (RPOs) and thei r contractors were responsible for preparing modeling emissions inventories for use in the OTC CMAQ SIP-quality modeling. The RPOs prepared a set of accurate, up- to-date, and quality assured emissions inventories for the 2002 Base Case and th ree future years, 2009, 2012, and 2018. For the future years, emissions inventories were prepared for two emissions control scenarios: one reflecting those emissions c ontrols that are in place or likely to be in place by 2009, and another that reflects additio nal control strategies that may be needed to demonstrate attainment with the eight-hou r ozone standard. The first scenario is referred to as “On The Books/On The Way” (OTB/OT W), and the second is referred to as “Beyond On The Way” (BOTW). These inventories w ere broken down into the following general emissions source categories: biog enic, point, area, non-road mobile, and on-road mobile.

Using these inventories, NYSDEC and the other model ing centers, the Virginia Department of Environmental Quality (VADEQ) and Nor theast States for Coordinated Air Use Management (NESCAUM), generated the necessa ry emissions inputs for CMAQ using the Sparse Matrix Operator Kernel Emissions ( SMOKE) model. For the CALGRID modeling effort, the pre-merged SMOKE emiss ions files were obtained from the modeling centers and re-formatted for input int o EMSPROC, the emissions preprocessor for the CALGRID modeling system. The pre -merged SMOKE files that were obtained from the modeling centers were broken down into the biogenic, point, area, nonroad, and on-road categories mentioned earlier. Th ese files by component were then converted for use with EMSPROC, thus giving users o f the CALGRID modeling system the flexibility to analyze a wide variety of emissi ons control strategies. QA/QC plots were generated during the re-formatting of the emis sions data to ensure that an accurate modeling inventory was generated for the CALGRID pl atform. Example emissions QA/QC plots are shown in Figures 5 through 8.6

Figure 5: QA/QC Plot of Surface Source CO Emissions

Figure 6: QA/QC Plot of Surface Source VOC Emission s7

Figure 7: QA/QC Plot of Point Source NOx Emissions

Figure 8: QA/QC Plot of Point Source SO2 Emissions8

3.0 CALGRID Model Outputs

A variety of post-processing programs have been dev eloped to assist users of the CALGRID modeling platform in visualizing and tabula ting model results. These postprocessors are designed to take the hourly concentr ation output generated by the CALGRID model and produce statistical results for d esired averaging periods and geographic areas. CALGRID can also generate output suitable for plotting with standard graphical packages such as the Center for Ocean-Lan d-Atmosphere Studies’ Grid Analysis and Display System (GrADS) or Golden Softw are’s SURFER.

As with the CMAQ SIP-quality modeling platform, it was decided that the CALGRID screening results should be used in a relative mann er. Ratios of model-predicted base case and future scenario concentrations would be ap plied to current monitored ozone design values to generate estimated future design v alues (DVFs) for the future-year scenario of interest. It is these DVFs that are us ed in the determination of attainment.

4.0 Episode Selection

For the CMAQ SIP-quality modeling analysis, the fiv e-month ozone season of 2002 was selected for modeling because it met EPA’s episode selection criteria of containing episode days that are meteorologically representati ve of typical high ozone exceedance days and that are severe enough that any control st rategy that is predicted to reach attainment on those days would reach attainment on other less severe days.

Similarly, the CALGRID screening platform was run f or the summer period from May 15 to September 15, 2002 for the 2002 Base Case and 20 09 OTB/OTW and BOTW scenarios. However, running the full summer episod e, even with the CALGRID screening platform, is very time-consuming and reso urce intensive. In order to increase production and maximize the number of scenarios tha t can be evaluated with the CALGRID screening platform, it was decided that sho rter modeling episodes would be selected that adequately reproduced the results obt ained by running the full summer episode. An extensive analysis was undertaken to r un a number of shorter summer episodes and compare the resulting predicted DVFs w ith those obtained for the full summer episode. The 2002 Base Case and 2009 OTB/OT W scenarios were used in this evaluation. It was found that the combined DVFs ca lculated from the July 6 to July 23, 2002 and July 30 to August 16, 2002 modeling episod es best represented those from the full summer episode (note that July 6 th and July 30 th are considered to be model warm-up days).

5.0 CALGRID Model Performance Evaluation

A qualitative and quantitative assessment was made of the CALGRID screening platform’s ability to reproduce observed ozone conc entrations. To assess its performance, the CALGRID screening platform was run for the 2002 Base Case for the July 30 to August 16, 2002 modeling episode. Predi cted maximum eight-hour ozone concentrations at monitor locations were compared a gainst observations for 2002. Figure9

9 shows the relative bias between maximum eight-hou r ozone observations and predicted CALGRID eight-hour ozone concentrations for the 200 2 Base Case for the episode from July 30 through August 12. Figures 10 through 13 s how plots of predicted 2002 Base Case ozone concentrations against 2002 observations for selected episode days. Although the CALGRID model has a tendency to over-p redict, especially in the urban core areas of northern Virginia, Maryland, southeas tern Pennsylvania, New York City and Boston, it does a reasonable job of reproducing the pattern of the 2002 maximum ozone observations.

Figure 9: Relative Bias Between Maximum 8-hour Ozon e Concentrations Predicted with CALGRID and Observations 

# Relative Bias (CALGRID minus Observed)

-20 to -15
-15 to -10
-10 to -5
-5 to -2
-2 to 2
2 to 5
5 to 10
10 to 15
15 to 20
20 to 50 

### 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 11/21/0610

Figure 10: Comparison of Maximum 8-hour Ozone Conce ntrations for August 11, 2002

Maximum 8-Hour Ozone Concentrations CALGRID - 2002 Base Case OTC Modeling Domain - August 11, 2002

Ozone Concentrations (PPB)

NHDES 11/21/06 0 to 40
40 to 50
50 to 60
60 to 70
70 to 80
80 to 90
90 to 100
100 to 150

Figure 11: Comparison of Maximum 8-hour Ozone Conce ntrations for August 12, 2002

Maximum 8-Hour Ozone Concentrations CALGRID - 2002 Base Case OTC Modeling Domain - August 12, 2002

Ozone Concentrations (PPB)

NHDES 11/21/06 0 to 40
40 to 50
50 to 60
60 to 70
70 to 80
80 to 90
90 to 100
100 to 15011

Figure 12: Comparison of Maximum 8-hour Ozone Conce ntrations for August 13, 2002

Maximum 8-Hour Ozone Concentrations CALGRID - 2002 Base Case OTC Modeling Domain - August 13, 2002

Ozone Concentrations (PPB)

NHDES 11/27/06 0 to 40
40 to 50
50 to 60
60 to 70
70 to 80
80 to 90
90 to 100
100 to 150

Figure 13: Comparison of Maximum 8-hour Ozone Conce ntrations for August 14, 2002

Maximum 8-Hour Ozone Concentrations CALGRID - 2002 Base Case OTC Modeling Domain - August 14, 2002

Ozone Concentrations (PPB)

NHDES 11/27/06 0 to 40
40 to 50
50 to 60
60 to 70
70 to 80
80 to 90
90 to 100
100 to 15012

6.0 CALGRID Model Runs

The OTC CALGRID modeling platform will be run for t he 2002 Base Case, 2009 OTB/OTB, and 2009 BOTW. These simulations will be run for the full summer (May 15 to September 15, 2002) episode as well as for the s horter summer modeling episodes described earlier. A variety of control scenarios and sensitivity runs will be performed for the shorter episodes as requested by the OTC Mo deling Committee or individual state agencies. The results of these runs may be used to evaluate, at a screening level, any additional emissions reductions that may be require d, thus relieving the technical burden on the CMAQ modeling centers. CALGRID screening re sults may also be used in individual states’ weight-of-evidence (WOE) analyse s. If states request it, the CALGRID modeling platform will be delivered so that they ma y run additional modeling scenarios at their discretion.