CARBON MONOXIDE (CO) PLAYS A KEY ROLE IN ATMOSPHERIC CHEMISTRY AND CLIMATE AS A PRECURSOR TO OZONE AND CARBON DIOXIDE. CO IS EMITTED DIRECTLY BY INCOMPLETE COMBUSTION PROCESSES BOTH ANTHROPOGENIC AND NATURAL AND INDIRECTLY BY SECONDARY CHEMICAL PRODUCTION FROM HYDROCARBON EMISSIONS. THE PRIMARY DESTRUCTION OF CO IS THROUGH REACTIONS WITH OH THAT AFFECT THE OXIDIZING CAPACITY OF THE TROPOSPHERE AND CONSEQUENTLY THE LIFETIME OF METHANE. ACCOUNTING FOR THESE EFFECTS EMISSIONS OF CO HAVE A SIGNIFICANT INDIRECT RADIATIVE FORCING OF 0.23 W/M2 (IPCC AR5). FURTHERMORE CO PLAYS A USEFUL ROLE AS A TRACER OF LONG RANGE TRANSPORT FROM POLLUTION SOURCES SUCH AS URBAN AREAS AND LARGE SCALE BIOMASS BURNING DUE TO ITS LIFETIME OF 1-2 MONTHS. CO OBSERVATIONS ARE USED TO UNDERSTAND COMBUSTION EFFICIENCY WHEN MEASURED WITH CO2 AND NOX AND FIRE POLLUTANT EMISSIONS ARE OFTEN LISTED AS RATIOS WITH RESPECT TO CO EMISSIONS. DECADAL SCALE RECORDS OF GLOBAL CO OBSERVATIONS FROM SPACE ARE THEREFORE CRITICAL FOR EVALUATING CHEMISTRY/ CLIMATE MODEL EMISSIONS TRANSPORT AND CHEMICAL MECHANISMS AND ATTRIBUTING CHANGES IN CO DUE TO CLIMATE VARIABILITY VS. SUSTAINED REDUCTION OR GROWTH IN ANTHROPOGENIC EMISSIONS. THE NASA TERRA/MOPITT (MEASUREMENTS OF POLLUTION IN THE TROPOSPHERE) INSTRUMENT LAUNCHED IN DECEMBER 1999 AND STILL OPERATING PROVIDES THE LONGEST SATELLITE CO DATA RECORD AVAILABLE AND NOW SPANS SEVERAL ENSO (EL NINO/SOUTHERN OSCILLATION) CYCLES MAKING IT INVALUABLE FOR INVESTIGATING CLIMATE VARIABILITY IN TROPOSPHERIC COMPOSITION. MOPITT ALSO PROVIDES THE ONLY SATELLITE MEASUREMENTS OF CO ABSORPTION IN BOTH THE THERMAL AND NEAR-INFRARED (TIR AND NIR). THE SNPP/CRIS (CROSS-TRACK INFRARED SOUNDER) LAUNCHED IN 2011 MEASURES CO FROM TIR ABSORPTION. SNPP/CRIS AND THE PLANNED CRIS INSTRUMENTS ON JPSS (JOINT POLAR SATELLITE SYSTEM) SATELLITE MISSIONS HAVE THE POTENTIAL TO EXTEND THE MOPITT GLOBAL CO RECORD INTO THE NEXT 2 DECADES. WE PROPOSE TO FACILITATE A MERGED MOPITT/CRIS CO DATA RECORD BY USING A CONSISTENT RETRIEVAL APPROACH AND CHARACTERIZING MOPITT/CRIS BIASES DUE TO INSTRUMENT AND SAMPLING DIFFERENCES. THIS EFFORT BUILDS ON A NASA-ROSES 2013 A.29 SNPP PROJECT LED BY AER (ATMOSPHERIC AND ENVIRONMENTAL RESEARCH) TO APPLY THE MOPITT OPTIMAL ESTIMATION RETRIEVAL APPROACH TO CRIS SPECTRA AND DELIVER INPUT FILES ALGORITHMS AND ATBD TO THE JPL (JET PROPULSION LABORATORY) SNPP-SOUNDER SIPS (SCIENCE INVESTIGATOR-LED PROCESSING SYSTEM) FOR DEVELOPING AND TESTING OPERATIONAL RETRIEVALS. OUR PROPOSED EFFORT HERE WILL VALIDATE OPERATIONAL CRIS CO PRODUCTS FROM THE SIPS WITH INDEPENDENT CO MEASUREMENTS BOTH IN SITU AND REMOTELY SENSED AND CHARACTERIZE RETRIEVAL ERRORS DUE TO THE FORWARD MODEL ASSUMPTIONS SUCH AS WATER VAPOR ABUNDANCE. WE WILL ALSO INVESTIGATE GLOBAL AND REGIONAL DECADAL SCALE TRENDS IN CO. DATA ASSIMILATION OF BOTH MOPITT AND CRIS CO IN THE NCAR COMMUNITY ATMOSPHERE MODEL WITH CHEMISTRY (CAM-CHEM) WILL BE USED FOR UNDERSTANDING THE CHEMICAL EFFECTS OF CHANGING CO AS WELL AS PROVIDING A MEANS I.E. TRANSFER FUNCTION TO COMPARE WITH SURFACE CO OBSERVATIONS. FINALLY ASSUMING THE SUCCESSFUL 2017 LAUNCH OF ESA-S5P/TROPOMI (TROPOSPHERIC MONITORING INSTRUMENT) WHICH WILL FLY IN LOOSE FORMATION WITH SNPP WE WILL PURSUE MULTISPECTRAL CO RETRIEVALS USING CRIS TIR (4.6 MICRON) AND TROPOMI NIR (2.3 MICRON) SPECTRAL RADIANCES TO EXTEND THE UNIQUE MULTISPECTRAL CO RECORD OF MOPITT.