THE WORK PROPOSED HERE AIMS TO IMPROVE OUR UNDERSTANDING OF THE EMISSIONS AND FATE OF VOLATILE ORGANIC COMPOUNDS (VOCS) THROUGH LONG-TERM FORMALDEHYDE (HCHO) OBSERVATIONS IN AND NEAR AN URBAN AREA. VOC SOURCES ARE NOTORIOUSLY UNDER-CHARACTERIZED ESPECIALLY IN URBAN AREAS WHERE BIOGENIC EMISSIONS MODELS MAY BE LESS ACCURATE AND SOME ANTHROPOGENIC SOURCE SECTORS REMAIN UNQUANTIFIED. AS BOTH A VOC OXIDATION PRODUCT AND A SOURCE OF OXIDANTS HCHO IS A CENTRAL TEST-POINT FOR MODELS OF SECONDARY POLLUTANT FORMATION. THE RECENT LAUNCH OF TROPOMI AND NEAR-FUTURE LAUNCH OF TEMPO GIVE NEW ABILITY TO RESOLVE HCHO ENHANCEMENTS IN AN URBAN OUTFLOW BUT MORE WORK IS NEEDED TO UNDERSTAND BIASES IN SATELLITE-BASED HCHO MEASUREMENTS AND THEIR RELATIONSHIP TO SURFACE LEVEL CONCENTRATIONS AND OZONE FORMATION. PROJECT GOALS ARE ENCOMPASSED IN THREE OBJECTIVES: (1) IMPLEMENT A MORE ACCURATE LESS RESOURCE INTENSIVE HCHO MONITORING STRATEGY TO AID IN THE INTERPRETATION OF CURRENT AND NEAR FUTURE SATELLITE BASED HCHO OBSERVATIONS. (2) DETERMINE THE DRIVING CAUSES OF SPATIOTEMPORAL HCHO VARIABILITY ACROSS AN URBAN-RURAL GRADIENT AND EVALUATE THE RELATIONSHIP BETWEEN OBSERVED VARIABILITY URBAN EMISSIONS AND OZONE PRODUCTION. (3) WORK WITH LOCAL AIR QUALITY MANAGERS TO IMPROVE THE USE OF SATELLITE BASED HCHO IN THEIR ANALYSIS OF OZONE PRODUCTION SENSITIVITIES AND SEVERE POLLUTION EVENTS. PANDORA INSTRUMENTS AND AERIS HCHO SENSORS WILL DEPLOYED IN AND AROUND ATLANTA GA FOR AT LEAST ONE YEAR. HIGH RESOLUTION CHEMISTRY-TRANSPORT-MODELS WILL BE COMPARED TO OBSERVATIONS TO EXAMINE THE ACCURACY OF MODELED HCHO BUDGETS AND SENSITIVITY OF HCHO TO VOC AND NOX EMISSIONS. WE WILL USE BIAS-CORRECTED OBSERVATIONS TO REASSESS AND SATELLITE-BASED METRICS USED BY AIR QUALITY MANAGERS (E.G. HCHO/NO2) AND EXAMINE OZONE PRODUCTION DURING HEATWAVES. THIS PROJECT IS DIRECTLY IN LINE WITH THE GOALS OF NASA S EARTH SCIENCE AND THE ATMOSPHERIC COMPOSITION PROGRAM AS IT AIMS TO USE NASA EARTH SCIENCE PRODUCTS TO UNDERSTAND SPATIOTEMPORAL STRUCTURE OF AIR POLLUTANTS AND FURTHER THE USE OF REMOTELY-SENSED HCHO IN LOCAL AIR QUALITY MANAGEMENT.