WE PROPOSE TO EXTEND OUR REGIONAL MODELING FOR THE CARBON MONITORING SYSTEM (CMS) TO ESTIMATE NORTH AMERICAN CO2 FLUXES THROUGH MID-2018 IN ORDER TO TAKE ADVANTAGE OF NEW DATASETS WITH A FOCUS ON IMPROVING UNCERTAINTY QUANTIFICATION. CARBONTRACKER- LAGRANGE (CT-LAGRANGE) IS A HIGH-RESOLUTION REGIONAL INVERSE MODELING FRAMEWORK USED TO QUANTIFY CO2 FLUXES ON REGIONAL-TOCONTINENTAL SCALES THAT WAS ORIGINALLY DEVELOPED TO ANALYZE IN SITU MEASUREMENTS FROM THE NORTH AMERICAN CARBON PROGRAM. UNDER PREVIOUS CMS-FUNDED EFFORTS WE HAVE ADDED FOOTPRINTS (SURFACE INFLUENCE FUNCTIONS) FOR NASA REMOTE SENSING DATASETS INCLUDING ACOS-GOSAT, TCCON, AND OCO-2, AND WE HAVE DEVELOPED STRATEGIES TO INVESTIGATE CONSISTENCY AMONG IN SITU AND REMOTE SENSING DATASETS AND FOR COMBINING IN SITU AND REMOTE SENSING DATA FOR FLUX ESTIMATION. FOOTPRINTS (SURFACE INFLUENCE FUNCTIONS) FOR OVER 5 MILLION GROUND-BASED, AIRBORNE, AND SATELLITE MEASUREMENTS HAVE BEEN COMPUTED AND MADE FREELY AVAILABLE TO THE RESEARCH COMMUNITY. HERE WE PROPOSE TO: (1) ESTIMATE NORTH AMERICAN FLUXES USING THE FIRST FEW YEARS OF OCO-2 DATA BY EXTENDING THE CT-LAGRANGE FOOTPRINT LIBRARY, (2) INVESTIGATE ERRORS IN ESTIMATED FLUXES, WITH PARTICULAR ATTENTION TO ERRORS IN SIMULATED ATMOSPHERIC TRANSPORT BY LEVERAGING INDEPENDENT DATA AND MODELING ACTIVITIES FROM THE NASA ATMOSPHERIC CARBON AND TRANSPORT AMERICA (ACT-AMERICA) AND (3) CONDUCT A SET OF CONTINENTAL-SCALE OBSERVATION SYSTEM SIMULATION EXPERIMENTS IN PREPARATION FOR ANALYSIS OF DATA FROM THE NEWLY ANNOUNCED GEOSTATIONARY CARBON CYCLE OBSERVATORY (GEOCARB) MISSION. OUR PROJECT WILL MAKE EXTENSIVE USE OF NASA ASSETS, INCLUDING OCO-2 AND TCCON XCO 2, AND SOLAR-INDUCED CHLOROPHYLL FLUORESCENCE RETRIEVALS FROM OCO-2 AND ESA S GOME-2. WE WILL ALSO USE AND EVALUATE NASA MODEL PRODUCTS (E.G., MERRA TRANSPORT FIELDS AND CMS FLUX PRODUCTS), THUS STRENGTHENING LINKS BETWEEN CMS AND NOAA S CARBONTRACKER EFFORT AND SUPPORTING THE DEVELOPMENT OF AN INTEGRATED CARBON MONITORING SYSTEM. THE PROPOSED WORK WILL FURTHER DEVELOP STRATEGIES FOR INCORPORATING DIVERSE CO2 OBSERVATIONS INTO CMS FLUX PRODUCTS AND FOR QUANTIFYING FLUXES AND THEIR UNCERTAINTIES AT SCALES RELEVANT FOR UNDERSTANDING CARBON CYCLE PROCESSES AND FOR MONITORING, REPORTING AND VERIFICATION (MRV).