THE PRIMARY GOAL OF THIS PROJECT IS TO USE NASA RETRIEVALS OF BOUNDARY-LAYER CONCENTRATIONS OF AMMONIA (NH3) FROM THE CROSSTRACK INFRARED SPECTROMETER (CRIS) ABOARD THE SUOMI NATIONAL POLAR-ORBITING PARTNERSHIP SATELLITE TO PROVIDE IMPROVED EMISSION INVENTORIES OF NH3 TO AIR QUALITY MANAGERS FORECASTERS AND OTHER STAKEHOLDERS WHO NEED TO DETERMINE THE HUMAN HEALTH IMPACTS OF PM2.5 PRECURSORS LIKE NH3. AIR QUALITY MANAGERS HAVE INCREASINGLY FOCUSED ON CONTROLLING THE GROWING EMISSIONS OF NH3 AS A POTENTIAL STRATEGY TO REDUCE THESE HEALTH IMPACTS. FOR EXAMPLE THE LATEST EPA REGULATORY GUIDANCE ON ASSESSING THE IMPACTS OF NEW SOURCES OF PM2.5 PRECURSORS REQUIRES THAT EMISSIONS OF NH3 BE ADDRESSED. HOWEVER CURRENT NH3 EMISSION INVENTORIES ARE TOO UNCERTAIN TO PROVIDE CREDIBLE ESTIMATES OF THE ASSOCIATED HEALTH IMPACTS. OUR PROJECT TEAM HAS DEMONSTRATED THAT A FINITE-DIFFERENCE MASS-BALANCE APPROACH CAN USE CRIS NH3 OBSERVATIONS TO CONSTRAIN NH3 EMISSIONS AT THE RESOLUTIONS TYPICAL OF REGIONAL AIR QUALITY MODELING. IN THIS PROJECT WE WILL USE THESE NASA EARTH OBSERVATIONS TO PRODUCE IMPROVED MODEL-READY EMISSION FILES FOR NH3 (COVERING THE CURRENT AND FUTURE CRIS DATA RECORD) FOR THE MAIN US AND CANADIAN REGIONAL AIR QUALITY MODELS (CMAQ CAMX AND GEM-MACH). GIVEN OUR SUCCESSFUL PROOF-OF-CONCEPT TEST OUR PROPOSED APPLICATION IS CURRENTLY AT APPLICATION READINESS LEVEL (ARL) 3. IN THIS PROJECT WE WILL: (1) INTEGRATE THE NASA CRIS NH3 RETRIEVED PRODUCT AND OUR CMAQ-BASED INVERSION METHODOLOGY INTO A PROTOTYPE APPLICATION SYSTEM ON THE AMAZON CLOUD (ARL 4) (2) DEVELOP MODEL-READY UPDATED NH3 EMISSION FILES FOR CMAQ CAMX AND GEM-MACH AND BETA-TEST THEM IN THE END-USER APPLICATIONS (ARL 5) (3) DEMONSTRATE THAT THE PROTOTYPE APPLICATION IMPROVES THE SIMULATION OF NH3 AND INORGANIC PM2.5 IN END-USER MODELING AND LEADS TO BETTER DECISION MAKING (ARL 6) (4) FULLY INTEGRATE THE PROTOTYPE APPLICATION INTO END-USER DECISION-MAKING (ARL 7) WE WILL DESIGN OUR APPLICATION SO THAT THE EMISSION FILES CAN BE EASILY INCORPORATED INTO EXISTING MODELING ACTIVITIES BY GOVERNMENT AIR QUALITY MANAGERS (SUCH AS US EPA THE CENTRAL STATES AIR RESOURCE AGENCIES THE WESTERN REGIONAL AIR PARTNERSHIP AND ENVIRONMENT AND CLIMATE CHANGE CANADA) AIR QUALITY FORECASTERS (INCLUDING THE NOAA NATIONAL AIR QUALITY FORECAST CAPABILITY RESEARCH TEAM) AND INDUSTRY STAKEHOLDERS (SUCH AS THE MEMBERS OF THE ELECTRIC POWER RESEARCH INSTITUTE). THESE FILES WILL BE PRODUCED VIA A CLOUD COMPUTING SYSTEM THAT BOTH AER AND END USERS WILL BE ABLE TO OPERATE AFTER NASA FUNDING ENDS. THE APPLICATION CODE WILL ALSO BE PROVIDED TO END USERS FOR THEIR OWN USE. AS NEW CRIS INSTRUMENTS WILL CONTINUE TO BE LAUNCHED OVER THE NEXT TWO DECADES OUR PROPOSED APPLICATION WILL PROVIDE INFORMATION ON THE EMISSIONS OF NH3 TO DECISION-MAKERS FOR MANY YEARS INTO THE FUTURE. OUR PROJECT TEAM HAS A RECORD OF PROVEN PERFORMANCE ON ALL ASPECTS OF THIS PROJECT INCLUDING SATELLITE RETRIEVALS OF NH3 INVERSION MODELING TO IMPROVE EMISSION INVENTORIES AND DEVELOPING CLOUD-BASED SCIENTIFIC SOFTWARE APPLICATIONS. THIS PROJECT WILL THUS USE NASA EARTH OBSERVATIONS TO DEVELOP AN IMPROVED REPRESENTATION OF NH3 EMISSIONS THAT WILL DIRECTLY IMPACT POLICY AND INVESTMENT DECISIONS RELATED TO AIR QUALITY AND HUMAN HEALTH.