IGF::OT::IGF OTHER FUNCTIONS THIS EFFORT IS FOR A CONTINUATION OF NASA GSFC'S ACTIVITIES RELATED TO THE CARBON MONITORING SYSTEM, FLUX PILOT STUDY (CMS FPP). THE WORK WILL ENHANCE AND DEVELOP THE CAPABILITIES OF NASA'S GODDARD EARTH OBSERVING SYSTEM (GEOS) SET OF MODELS AND ASSIMILATION COMPONENTS TO FURTHER DEVELOP A CORE CAPABILITY FOR CMS-RELATED CARBON CYCLE SCIENCE AND MONITORING. THE WORK CONSISTS OF THREE COMPONENTS: (I) CONTINUATION OF PAST WORK TO COMPUTE ATMOSPHERE-OCEAN AND ATMOSPHERE-LAND BIOSPHERE FLUXES, AS WELL AS THEIR EVALUATION USING FORWARD MODELING IN GEOS-5; (II) ENHANCEMENTS OF GEOS-5 FOR CARBON MONITORING, INCLUDING A MODEL STUDY OF THE INTERMINGLING OF UNCERTAINTIES IN ANTHROPOGENIC AND LAND-BIOSPHERIC CARBON EMISSIONS, AND DEVELOPMENT OF AN ENHANCED ASSIMILATION CAPABILITY TO INCLUDE MULTIPLE SPACE-BORNE CO2 ESTIMATES (FROM AIRS AND ACOS-GOSAT); (III) A FOCUSED ACTIVITY THAT EXAMINES ASPECTS RELATED TO TOP-DOWN (INVERSE) ESTIMATES OF CARBON FLUXES. THE LATTER EFFORT WILL INCLUDE A CONTROLLED COMPARISON OF THREE INVERSE ESTIMATES, INCLUDING THE ONE FROM CMS FPP, THAT USE THE SAME INPUT DATA BUT USE DIFFERENT METHODS. IT ALSO INCLUDES THE IMPLEMENTATION AND APPLICATION OF A LAGRANGIAN PARTICLE DISPERSION MODEL TO COMPUTE GLOBAL FOOTPRINTS OF GOSAT OBSERVATIONS. FURTHER, SUBSTANTIAL NEW DEVELOPMENTS WILL BE IMPLEMENTED INTO AN EXISTING VARIATION INVERSION SYSTEM. THE WORK PROPOSED IN GEOS-CARB WILL IMPLEMENT AND ADAPT VARIOUS MODELING AND ANALYSIS TOOLS, LINKING THEM CLOSELY WITH GEOS-5 SYSTEMS AVAILABLE IN THE GLOBAL MODELING AND ASSIMILATION OFFICE, IN ORDER TO BETTER EXPLOIT NASA S CARBON-RELEVANT OBSERVATIONS FOR MONITORING AND UNDERSTANDING THE GLOBAL CARBON CYCLE. THE DEVELOPMENT WORK WILL LEAVE NASA WITH ENHANCED MODELING AND ANALYSIS TOOLS FOR CARBON-CYCLE MONITORING USING SPACE-BASED OBSERVATIONS. THESE TOOLS WILL BE USED TO ADDRESS SOME OF THE RESEARCH QUESTIONS THAT HAVE ARISEN IN THE COURSE OF CMS FPP, WITH A STRONG EMPHASIS ON CHARACTERIZING UNCERTAINTY IN CO2 FLUX COMPUTATIONS.