# 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 033021.0 Introduction

The Ozone Transport Commission (OTC) has sponsored the development of a photochemical modeling system to assist st ates in the preparation of their State Implementation Plans (SIPs) for attaining the eight-hour National Ambient Air Quality Standard (NAAQS) for ozone. The Commun ity Multiscale Air Quality Model (CMAQ) is the basis of the OTC SIP-qua lity modeling platform that is being used in states’ eighthour ozone attainment SIPs.

Running the CMAQ modeli ng platform is very resource intensive and usually requires the use of a Unix-based operating system. Therefore, the CMAQ modeling that is being done in support of the eight-hour ozone SIPs is limited to a handful of modeling centers that have the necessary expertise and com puter resources. Similarly, because of the substantial effort, time, and storage sp ace required to run the SIP-quality CMAQ platform, it is impractical to assess a large number of run scenarios.

Consequently, OTC sponsored the development of an additional grid-based photochemical modeling platform that states could use as a screen ing tool for running additional emissions control strategies or performing 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 this manner, a larger number of run scenarios could be modeled, allowing states to screen a wider variety of potential control strategies.

The California Grid Model (CALGRID) was se lected as the basis of this screening platform. CALGRID is a grid -based photochemical modeling platform that is designed to be run in a Windows environment. CA LGRID has recently undergone a series of improvements and enhancements, with the most recent version being designated CALGRID Version 2.45. CALG RID Version 2.45 is being used as the screening platform for the OTC eight-hour ozone atta inment SIPs. This document outlines the manner in which CALGRID will be used in these efforts.

2.0 Platform Description and Model Inputs

To make the CALGRID modeling platform the best possible tool to supplement the SIPquality CMAQ platform, it was decided th at 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 writte n to convert these inputs into a format useable by the CALGRID model. The modeli ng 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. The

1southwest 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, the processing programs that were used to reformat the boundary conditions, meteorology, and emissions mapped the 22 layers used for CM AQ to a total of nine vertical layers for the CALGRID modeling. The OTC CMAQ/ CALGRID modeling domain is shown in Figure 1.

Figure 1: Map of the OTC CMAQ/CALGRID Modeling Domain



## 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 condi tions were derived from GEOS-Chem (Goddard Earth Observing System) global atmospheric simulations by running CMAQ on the 36-km continental grid. For the CA LGRID platform, initial conditions, side

2boundary conditions, and top layer concentrations were derived from the CMAQ boundary conditions files by means of a pro cessing program. This program mapped the 22 vertical layers used in th e 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 user could begin a CALGRID simulation on any desired episode day.

2.3 Meteorology

The meteorological modeling that was done in support of the OTC CMAQ SIP-quality modeling platform was performed by the Un iversity of Maryland (UMD) in conjunction with staff at the New York State Department of Environmental Conservation (NYSDEC). UMD used the Penn State/National Center for Atmospheric Research 5 th Generation Mesoscale Model (MM5) Version 3.6 to gene rate year 2002 meteorological inputs. The details of this work are described in NYSDEC’s Technical Support Document TSD-1a, Meteorological Modeling Using Penn State/NCAR 5 th Generation Mesoscale Model (MM5), February 1, 2006. For the CALGRID modeling pl atform, 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 in terpolated data. Figures 2 through 4 show example QA/QC plots from the re-formatting of the meteorological 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 30000

3Figure 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 Eastin g ( 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 1.5

42.4 Emissions

The Regional Planning Organizations (RPOs) and their contractors were responsible for preparing modeling emissions inventorie s 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 Ca se and three future years, 2009, 2012, and 2018. For the future years, emissions inve ntories were prepared for two emissions control scenarios: one reflecting those emissions controls that are in place or likely to be in place by 2009, and another th at reflects additional contro l strategies that may be needed to demonstrate attainment with the ei ght-hour ozone standard. The first scenario is referred to as “On The Books/On The Way” (OTB/OTW), and the second is referred to as “Beyond On The Way” (BOTW). These inventories were broken down into the following general emissions source categories: biogenic, point, area, non-road mobile, and on-road mobile.

Using these inventories, NYSDEC and the other modeli ng centers, the Virginia Department of Environmental Quality (VADE Q) and Northeast States for Coordinated Air Use Management (NESCAUM), generate d the necessary emissions inputs for CMAQ using the Sparse Matrix Op erator Kernel Emissions (SMOKE) model. For the CALGRID modeling effort, the pre-merged SM OKE emissions files were obtained from the modeling centers and re-formatted for input into EMSPROC, the emissions preprocessor for the CALGRID modeling system. The pre-merged SMOKE files that were obtained from the modeling centers were br oken down into the biogenic, point, area, nonroad, and on-road categories mentioned earlie r. These files by component were then converted for use with EMSPROC, thus givi ng users of the CALGRID modeling system the flexibility to analyze a wide variety of emissions control strategies. QA/QC plots were generated during the re-for matting 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 5 through 8.

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

Figure 6: QA/QC Plot of Surface Source VOC Emissions

6Figure 7: QA/QC Plot of Point Source NOx Emissions

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

73.0 CALGRID Model Outputs

A variety of post-processing programs have been develope d to assist users of the CALGRID modeling platform in visualizing and tabulating model results. These postprocessors are designed to take the h ourly concentration output generated by the CALGRID model and produce st atistical results for desi red averaging periods and geographic areas. CALGRID can also generate output suitable for plotting with standard graphical packages such as the Center for Ocean-Land-Atmosphere Studies’ Grid Analysis and Display System (GrADS) or Golden Software’s SURFER.

As with the CMAQ SIP-quality modeling pl atform, it was decided that the CALGRID screening results should be us ed in a relative manner. Ra tios of model-predicted base case and future scenario concentrations w ould be applied to current monitored ozone design values to generate estimated future design values (DVFs) for the future-year scenario of interest. It is these DVFs that are used in the determination of attainment.

4.0 Episode Selection

For the CMAQ SIP-quality modeling analysis, the five-month ozone season of 2002 was selected for modeling because it met EPA’s episode selection criteria of containing episode days that are meteorologically repr esentative of typical high ozone exceedance days and that are severe e nough that any control strategy th at is predicted to reach attainment on those days would reach a ttainment on other less severe days.

Similarly, the CALGRID screening platform was run for the summer period from May 15 to September 15, 2002 for the 2002 Base Case and 2009 OTB/OTW and BOTW scenarios. However, running the full summer episode, even with the CALGRID screening platform, is very time-consuming a nd resource intensive. In order to increase production and maximize the number of scen arios that can be evaluated with the CALGRID screening platform, it was decided that shorter modeling episodes would be selected that adequately re produced the results obtained by running the full summer episode. An extensive analysis was undert aken to run a number of shorter summer episodes and compare the resulting predicte d DVFs with those obtained for the full summer episode. The 2002 Base Case and 2009 OTB/OTW scenarios were used in this evaluation. It was found that the combined DV Fs calculated from th e July 6 to July 23, 2002 and July 30 to August 16, 2002 modeling ep isodes 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 concentrations. To assess its performance, the CALGRID screening platfo rm was run for the 2002 Base Case for the July 30 to August 16, 2002 modeling episode. Predicted maximum eight-hour ozone concentrations at monitor locations were co mpared against observations for 2002. Figure

89 shows the relative bias between maximum eight-hour ozone observa tions and predicted CALGRID eight-hour ozone con centrations for the 2002 Base Case for the episode from July 30 through August 12. Figures 10 through 13 show plots of predicted 2002 Base Case ozone concentrations against 2002 observations for selected episode days. Although the CALGRID model has a tendency to over-predict, especially in the urban core areas of northern Virginia, Maryland, s outheastern Pennsylvania, New York City and Boston, it does a reasonable job of re producing the pattern of the 2002 maximum ozone observations.

Figure 9: Relative Bias Between Maximum 8-hour Ozone 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 11/21/06

9Figure 10: Comparison of Maximum 8-hour Ozone Concentrations 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 Concentrations 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 150

10Figure 12: Comparison of Maximum 8-hour Ozone Concentrations 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 Concentrations 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 150

116.0 CALGRID Model Runs

The OTC CALGRID modeling platform w ill be run for the 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 shorter summer modeling episodes described earlier. A variety of control scenarios and sensitivity runs will be performed for the shorter episodes as requested by th e OTC Modeling 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 required, thus re lieving the technical burden on the CMAQ modeling centers. CALGRID scr eening results may also be used in individual states’ weight-of-evidence (WOE) an alyses. If states request it, the CALGRID modeling platform will be delivered so that they may run additional modeling scenarios at their discretion.

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