THIS PROPOSAL IS IN RESPONSE TO THE NASA ROSES 2018 A.19 SOLICITATION (NNH18ZDA001N-ACMAP). IN PARTICULAR WE PROPOSE TO USE REMOTE SENSING DATA PRODUCTS FOR ATMOSPHERIC COMPOSITION TO DEMONSTRATE SYNERGIES BETWEEN AQ AND GHG MEGACITY-SCALE EMISSIONS MONITORING. QUANTIFYING THE ANTHROPOGENIC SOURCES OF CO2 AND CH4 IS IMPERATIVE YET CHALLENGING. HERE WE PROPOSE A 3-YEAR PROGRAM OF RESEARCH TO DEVELOP IMPLEMENT AND IMPROVE A MULTI-SPECIES DATA ANALYSIS FRAMEWORK FOR ENHANCING GHG SIGNATURES FROM ANTHROPOGENIC ACTIVITIES THROUGH THE SYNERGISTIC USE OF SATELLITE-DERIVED MEASUREMENTS OF COMBUSTION-RELATED TRACE GASES (AQ: CO AND NO2 GHG: CO2 AND CH4) AND GLOBAL CHEMISTRY TRANSPORT MODELING VALIDATED WITH GROUND-BASED AND AIRBORNE MEASUREMENTS FROM NASA FIELD CAMPAIGNS AND AQ/GHG GROUND STATION NETWORK. THE PROGRAM THAT WE PROPOSE IS A DIRECT EXTENSION OF OUR PAST AND CURRENT NASA ACMAP RESEARCH ACTIVITIES WHICH MAINLY FOCUS ON PROOF-OF-CONCEPT STUDIES ON THE SYNERGIES OF AQ AND GHG EMISSION ESTIMATION. FOR THIS PROPOSED WORK WE ARE MOVING PAST THESE PROOF-OF-CONCEPTS TO QUANTIFYING THESE SYNERGIES. WE INTEND TO EXPLORE INTEGRATED DATA AND MODELING ANALYSIS APPROACHES IN USING CURRENT NASA OBSERVATIONAL CAPABILITIES TRADITIONALLY USED BY AIR QUALITY (AQ) COMMUNITY IN AUGMENTING CURRENT OBSERVATIONAL PROGRAMS ON CO2 AND CH4 EMISSIONS MONITORING. FIRST WE WILL CONDUCT AN EVALUATION OF MODELED ABUNDANCE OF CO NO2 CO2 AND CH4 FROM NCAR/CAM-CHEM FULL CHEMISTRY ENSEMBLE OF SIMULATIONS USING POSTERIOR FLUX ESTIMATES FROM LEADING INVERSE MODELING/DATA ASSIMILATION GROUPS (CARBON TRACKER AND CAMS FOR CO2 AND CH4 JAMSTEC REANALYSIS FOR CO AND NO2). WE WILL USE SATELLITE RETRIEVALS FROM OCO-2 (CO2) GOSAT (CO2 AND CH4) MOPITT (CO) OMI (NO2) TROPOMI (NO2 CO CH4) AND IASI (CO CO2 CH4) AIRCRAFT MEASUREMENTS FROM NASA KORUS-AQ (CO NO2 CO2 CH4) DISCOVER-AQ (CO NO2 CO2 CH4) ACT-AMERICA (CO CO2 CH4) AND ATOM (CO NO2 CO2 CH4) AS WELL AS GROUND PROFILE MEASUREMENTS FROM NOAA WDCGG STATION NETWORK (CO CO2 CH4) COLUMN MEASUREMENTS FROM TCCON (CO CO2 CH4) AND SURFACE AQ MEASUREMENTS (CO NO2) FROM GROUND NETWORKS LIKE USEPA. SECOND WE WILL TAG IN CAM-CHEM THE ANTHROPOGENIC EMISSIONS OF CO CO2 AND CH4 FROM TOP MEGACITIES OF THE WORLD ACROSS THE RECENT DECADE (2005-2018) IN ORDER TO TRACK COMBUSTION RELATED PLUMES AND EVALUATE ASSOCIATED CHEMICAL RATIOS OF THESE SPECIES. THIRD WE WILL CONDUCT AN ENSEMBLE OF JOINT BAYESIAN SYNTHESIS INVERSIONS (CO CO2 AND/OR CH4) FOR THESE MEGACITIES ACROSS THE STUDY PERIOD USING SATELLITE RETRIEVALS. THE MAIN RATIONALE BEHIND THIS PROJECT IS ANCHORED UPON THE UTILITY OF NO2 DATA TO IDENTIFY COMBUSTION ACTIVITY (FOR CO2) AND CO TO TRACK CORRESPONDING PLUMES AND TO PROVIDE INFORMATION ON COMBUSTION EFFICIENCY (DCO/DCO2). THESE COMBUSTION-RELATED AQ (CO AND NO2) AND GHG (CH4) GASES ARE STRONGLY COUPLED CHEMICALLY VIA OH (I.E. CO IS A SINK OF OH WHILE NO2 IS A SOURCE OF OH WITHIN THE TROPOSPHERIC O3 CHEMISTRY). THIS PROJECT WILL DEMONSTRATE HOW THESE TYPES OF INFORMATION CAN BE TRANSLATED TO IMPROVING PREDICTIVE CAPABILITY OF ANTHROPOGENIC CO2 AND CH4 DISTRIBUTION AS WELL AS TO IMPROVING EMISSION MONITORING AT MEGACITY AND DECADAL SCALE GIVEN THAT THESE SPECIES ARE EITHER CO-EMITTED DURING COMBUSTION (CONSTRAINTS ON CO2 SOURCES) OR COUPLED (CONSTRAINTS ON CH4 SINKS). THIS PROJECT PRESENTS A UNIQUE OPPORTUNITY TO LEVERAGE ON THE STRENGTHS OF NASA OBSERVATIONAL CAPABILITIES TOWARDS ADDRESSING A CRITICAL GAP (YET AN EMERGING CONCERN) IN QUANTIFYING CHANGES IN CLIMATE-AND-AQ-RELEVANT ANTHROPOGENIC CO2 AND CH4 AS WELL AS PROVIDING INSIGHTS TO FUTURE INTEGRATED/CONSTELLATION OF SATELLITE MISSIONS FOR ATMOSPHERIC COMPOSITION.