An Instrument to Enable Identification of Anthropogenic CO2 Emissions Using Concurrent CO Measurements

For ASCENDS the CO and CO2 measurements must coincide in both time and space. For ASCENDS changes in the CO concentrations in the lower atmosphere must be measured with sufficient accuracy to identify correlations in CO2 and CO caused by man-made sources. Given the temporal and spatial constraints of the ASCENDS mission and the nature of the atmospheric CO signal, this can only be done using the 2.3 micron band in conjunction with a 4.7 micron band measurement. A dual beam, single array detector Gas Filter Correlation Radiometer is an accurate and highly cost effective way to measure CO at the temporal and spatial resolutions required for ASCENDS. In order to separate physiological fluxes from biomass burning and fossil fuel use, the NRC report Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond requires ASCENDS to simultaneously measure boundary layer CO2 and an additional tracer, ideally carbon monoxide (CO). While this technology could ultimately benefit three of the decadal survey missions (ASCENDS, GEOCAPE, and GACM), the implementation described here is tailored to support the specific requirements of the ASCENDS mission concept. An active (laser based) system will be used to detect CO2 concentrations within a field of view approximately 110 meters in diameter at the ground. To be useful for ASCENDS, the CO concentrations must be measured at the same place, and the same time, with approximately the same field of view. Currently we are assuming 230 meters for the field of view for the CO measurement in our sensitivity calculations. Both the 4.7 and 2.3 micron channels will be required for the CO derivation, the 2.3 micron measurement is the more challenging and has not been demonstrated at (or even near) sufficient spatial and temporal resolution by any existing or developing instrument. Introduction