OCO2 3D Radiative Transfer Calculations

Clouds adjacent to a clear sky footprint can enhance the radiation field in each OCO2 observation band. We apply 3D radiative transfer models to map out these radiative enhancements as a function of solar zenith angle, molecular gas optical depth, OCO2 viewing angle, and cloud height. The radiative enhancements decrease in size as the viewing angle increases and as the gas optical depth increases. We present preliminary estimates of how far away from an isolated cloud the clear sky footprint needs to be in order to avoid the 3D effect. If available, we show how OCO2 XCO2 retrieval residuals vary as a function of cloud distance and height to see if the residuals are correlated to 3D cloud effects.