Air Quality Modeling Sensitivity to PBL Scheme
Qi Mao, Tennessee Valley Authority, Muscle Shoals, AL; and L. L. Gautney, T. M. Cook, M. E. Jacobs, S. N. Smith, and J. J. Kelsoe
The Community Multiscale Air Quality (CMAQ) modeling system developed by the United States Environmental Protection Agency (USEPA) was used along with the PSU/NCAR mesoscale modeling system MM5 model to study air quality modeling sensitivity to various planetary boundary layer (PBL) schemes implemented in MM5. Two 37-day periods, representing typical summer and winter periods, were selected for the simulations. The MM5 domain covered the continental U. S. while the CMAQ domain covered much of the central and eastern U. S. There were 34 vertical layers in MM5 and 18 in CMAQ. The horizontal resolution was 36 km for both. First, MM5 was run with five of the seven commonly used PBL schemes to generate a series of gridded meteorological fields. The data were then processed and converted by the meteorology-chemistry interface processor (MCIP) to produce meteorological input for CMAQ, in conjunction with the emission data prepared by the Sparse Matrix Operator Kernel Emissions (SMOKE) System.
The sensitivity of MM5-CMAQ modeling to the various PBL schemes was assessed and quantified by comparing model output against observations from the meteorological and the air quality monitoring networks within the CMAQ domain. The meteorological variables evaluated include surface and 850-mb temperature and wind, 2-meter mixing ratio, surface pressure, and cloud fraction over 50 surface sites and 21 sounding sites. The CMAQ variables include NO2, SO4, O3, and PM2.5 over several hundred monitoring locations. Results from statistical analysis indicate that domain-wide the performance of neither model is sensitive to the PBL scheme used in MM5. In addition, although model performance differences occur at a regional scale, the choice of PBL scheme does not appreciably affect the performance. Detailed results will be presented at the joint conference.
Extended Abstract (308K)
Session 2, ADVANCED MODELING OF DISPERSION AND AIR QUALITY ON ALL SCALES: Part II
Monday, 30 January 2006, 1:30 PM-2:30 PM, A407
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