2011b Overview

Overview

The Western Air Quality Study (WAQS) conducted a CAMx 2011b base case simulation using a 36 km resolution CONUS, 12 km resolution WESTUS and 4 km resolution Intermountain West (i.e., CO, UT, WY and northern NM) modeling domains with two-way grid nesting. The CAMx 2011b 36/12/4 km base case simulation results are available on the Intermountain West Data Warehouse (IWDW ) that includes model documentation , including a model performance evaluation. The modeling platform input and output files can be accessed through the IWDW Data Request Page , and a model-to-observation tool on the IWDW website allows users to compare and download paired PGM model output and observational data for specific monitor locations and time periods.

Ozone and PM source apportionment (SA) modeling was also conducted using an “a” and “b” versions of the CAMx 2011 database with results available through a SA wiki on the IWDW that includes an interactive Source Apportionment Visualization Tool (SA Vis Tool). Several rounds of SA were performed, due to resource constraints the ozone SA modeling (Round 2, 2011b version) was performed on the 36/12 km CONUS/WESTUS domains and the PM SA modeling was conducted on the 36 km CONUS domains, thus the CAMx SA modeling results will not exactly match the CAMx 2011b 36/12/4 km base case modeling results because different domains were used. Even the WAQS Round 2 CAMx 2011b 36/12 km ozone SA modeling results for the 12 km domain will not match the CAMx 2011b 36/12/4 km base case 12 km results because the two-way nesting will replace the 12 km modeling results by the 4 km results in the CAMx 2011b 36/12/4 km base case simulation.

Recommendations

The Intermountain West Data Warehouse – Western Air Quality Study (IWDW-WAQS) produced an updated air quality model platform for year 2011 (hereafter referred to as “2011b”). The 2011b model platform and individual components, as described below, have been reviewed and approved by the IWDW-WAQS Cooperating Agencies. The model products are released for use in regional air quality modeling studies by the cooperating agencies and for external users accepting the terms of the IWDW Data Use RecommendationsAgreement and authorized by the Cooperators.

One important improvement in the 2011b platform is in the consideration of how snow cover impacts ozone formation. Base11b uses WRF meteorology that includes SNODAS snow cover/snow depth data and versions of WRFCAMx and CAMx with specialized dynamical and chemical parameterizations for areas covered by snow. Simulation Base11b used a winter configuration for both WRF and CAMx for the months December 2010 through March 2011. The rest of the simulation year (April-Decebember 2011) used the same WRF data and the same version of CAMx as simulation Base11a.

Oil and gas emissions for the Williston Basin in Montana and the Great Plains Basin in the Dakotas are missing from simulation Base11b. The IWDW generated Base11b_v2 CAMx and CMAQ-ready emissions that include the missing Montana/Dakotas oil and gas sources. While the Base11b_v2 emissions data have been QA'd, they have not been run through an air quality model by the IWDW.

When ordering the Base11b Modeling Platform from the IWDW, the distribution package includes both the standard (v6.10) and winter version of CAMx and WRFCAMx. To reproduce the WAQS Base11b simulation, the winter configuration should only be used for December 2010 though March 31, 2011.

Please see the 2011b Release Memo for details about the 2011b model platform, including refinements to emissions, known model performance issues, and recommendations for use in user initiated modeling studies.