Modelin the Transport and Chemical Evolution of Onshore and Offshore Emissions and Their Impact on Local and Regional Air Quality Using a Variable-Grid-Resolution Air Quality Model

Adel Hanna

关键词: AIR POLLUTION;    AIR QUALITY;    BOUNDARY LAYERS;    CLOUDS;    COASTAL REGIONS;    COMPLEX TERRAIN;    EXPLORATION;    GULF OF MEXICO;    MOISTURE;    OZONE;    POLLUTANTS;    POLLUTION;    REMOTE SENSING;    RESOLUTION;    SEAS;    TROPOSPHERE;    URBAN AREAS;   

DOI  :  10.2172/962694
RP-ID  :  None
PID  :  OSTI ID: 962694
Others  :  TRN: US200917%%89

学科分类：环境科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

The overall objective of this research project was to develop an innovative modeling technique to adequately model the offshore/onshore transport of pollutants. The variable-grid modeling approach that was developed alleviates many of the shortcomings of the traditionally used nested regular-grid modeling approach, in particular related to biases near boundaries and the excessive computational requirements when using nested grids. The Gulf of Mexico region contiguous to the Houston-Galveston area and southern Louisiana was chosen as a test bed for the variable-grid modeling approach. In addition to the onshore high pollution emissions from various sources in those areas, emissions from on-shore and off-shore oil and gas exploration and production are additional sources of air pollution. We identified case studies for which to perform meteorological and air quality model simulations. Our approach included developing and evaluating the meteorological, emissions, and chemistry-transport modeling components for the variable-grid applications, with special focus on the geographic areas where the finest grid resolution was used. We evaluated the performance of two atmospheric boundary layer (ABL) schemes, and identified the best-performing scheme for simulating mesoscale circulations for different grid resolutions. Use of a newly developed surface data assimilation scheme resulted in improved meteorological model simulations. We also successfully ingested satellite-derived sea surface temperatures (SSTs) into the meteorological model simulations, leading to further improvements in simulated wind, temperature, and moisture fields. These improved meteorological fields were important for variable-grid simulations, especially related to capturing the land-sea breeze circulations that are critical for modeling offshore/onshore transport of pollutants in the Gulf region. We developed SMOKE-VGR, the variable-grid version of the SMOKE emissions processing model, and tested and evaluated this new system. We completed the development of our variable-grid-resolution air quality model (MAQSIP-VGR) and performed various diagnostic tests related to an enhanced cloud parameterization scheme. We also developed an important tool for variable-grid graphics using Google Earth. We ran the MAQSIP-VGR for the Houston-Galveston and southern Louisiana domains for an August 23 to September 2, 2002, episode. Results of the modeling simulations highlighted the usefulness of the variable-grid modeling approach when simulating complex terrain processes related to land and sea close to an urban area. Our results showed that realistic SST patterns based on remote sensing are critical to capturing the land-sea breeze, in particular the inland intrusion of the reversed mesoscale circulation that is critical for simulating air pollution over urban areas near coastal regions. Besides capturing the correct horizontal gradient between land and sea surface temperatures, it is important to use an adequate ABL scheme in order to quantify correctly the vertical profiles of various parameters. The ABL scheme should capture the dynamics of the marine boundary layer, which is not often considered in a typical simulation over land. Our results further showed the effect of using satellite-derived SSTs on the horizontal and vertical extent of the modeled pollution pattern, and the increase in hourly ozone concentrations associated with changes in ABL characteristics resulting from the enhanced mesoscale circulation in the lower troposphere.