This project addresses the Air Quality Application Area, and its purpose is to improve the performance of the air quality management Decision Support Tools (DSTs) used in the State Implementation Plan (SIP) process for development and evaluation of emission controls under the provisions of the Clean Air Act. The specific DST targeted is the U.S. EPA?s developed CMAQ modeling system used by many State and Local air quality management agencies to determine future compliance with the National Ambient Air Quality Standards (NAAQS). Satellite data will be used to improve the quality and accuracy of retrospective baseline simulation in which proposed emission reductions are tested. Nationally, billions of dollars in emission reduction scenarios are tested using these DSTs. Thus, accuracy in the DST is critical to determining efficient cost effective strategies for attaining the NAAQS. Two critical areas in the DSS will be targeted for improvement. The fi rst is in improving model location and timing of clouds. Clouds have a profound role in photolysis activity, boundary-layer development and deep vertical mixing of pollutants and precursors. Satellite products to be incorporated or used for evaluation are GOES Vis and IR, CLOUDSAT liquid water, and Aqua/Terra thermodynamic profiles. Also, a new NASA Lightning NO-production Model (LNOM) that accounts for lightning NO production in convective clouds will be tested. The second area targeted is in improving chemical transboundary and initial conditions in the air quality model. The satellite products include MODIS aerosol and newly available OMI ozone profiles that can significantly impact the realization of the chemical state of the atmosphere. The project will facilitate routine utilization of NASA satellite products in the DST. The applied partner in this project is EPA?s Atmospheric Modeling Division (AMD) at the National Environmental Research Laboratory (NERL). Additionally, Georgia and Texas will serv e as test-beds for end users.