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Atmospheric Composition

Satellite instruments provide the means of multi-year observations of tropospheric NO2 and O3 over North America with sufficient temporal and spatial resolutions. These observations provide valuable constraints on understanding the factors influencing tropospheric air quality. We propose to apply the regional chemical transport model (REAM) and global GEOS-Chem model to analyze OMI, GOME2, MLS, and TES summertime observations over the United States. We will improve OMI and GOME2 tropospheric NO2 vertical column retrievals by conducting detailed comparisons of the algorithms used by NASA Goddard and Dutch KNMI. Preliminary analysis indicates that adopting high-resolution regional model NO2 profiles as a priori significantly improves the retrieval results. Lightning is the dominant source of NOx in the upper troposphere in summer. We improve model parameterizations of lightning NOx production by conducting process-based modeling using flash characteristics observed by the VHF lightning mapping systems in addition to NLDN measurements and satellite climatology. The research objectives are: (1) Characterize the observed distributions and variability of tropospheric NO2. Quantify the retrieval uncertainties of tropospheric NO2 and assess the impacts on modeling analysis. (2) Characterize the observed distributions and variability of lightning flash rates. Improve lightning NOx production parameterizations used in 3-D models through process-based modeling using available observations of cloud-ground (CG) flash rate, (intra-cloud) IC/CG ratio, and channel length and altitude. (3) Apply the model simulations to assess the impacts of surface and lightning NOx emissions on tropospheric NO2 columns and attribute the observed distributions and variability to emissions and atmospheric processes. (4) Characterize the observed distributions and variability of tropospheric O3. Analyze the contributions to the observed spatial variability of tropospheric O3 by production from surface and lightning NOx emissions and long-range transport.

The proposed research address NASA’s research objectives (3A.1), i.e., “(to) understand and improve predictive capability for changes in the ozone layer, climate forcing, and air quality associated with changes in atmospheric composition”. Specifically, the proposed research addresses the Area A of the ACMAP program (factors influencing tropospheric air quality).

In this project, we expect to improve the tropospheric NO2 vertical column retrievals for air quality/atmospheric chemistry studies over the United States. We also expect to improve lightning NOx parameterizations through process-based modeling constrained by the observations of flash characteristics. The modeling analysis of satellite measurements will be used to quantify the factors contributing to tropospheric NOx and O3 over the United States in summer.

Project PI:Yuhang Wang/Georgia Institude of Technology

Office: ES&T;, Rm. 3254, Dept of Earth & Atmospheric Sciences Georgia Institute of Technology POBox 0340

Phone: (404) 894-3995

Fax: (404) 894-5638

Email: ywang@eas.gatech.edu

http://apollo.eas.gatech.edu/people.html#Wang

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Started: Sep 03, 2010

Last Activity: Feb 02, 2011

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