Spectroscopic uncertainty impacts on OCO-2/3 retrievals of XCO2

Abstract

Estimates of atmospheric carbon dioxide concentration from satellites now span multiple years and are providing information on key processes in the carbon cycle. Methodology for retrieving CO2 from satellite spectra continues to change as understanding of instrument calibration, other atmospheric constituents, and trace gas spectroscopy improve. In this work, we provide an update to linear error estimates for retrieval of carbon dioxide for the Orbiting Carbon Observatory-2/3 (OCO-2/3) due spectroscopic uncertainties. Linear error analysis is used to propagate uncertainties in laboratory conditions and spectroscopic model assumptions to sensitivity in retrieved XCO2 and surface pressure from OCO-2/3. Error estimates due to modeling assumptions for line mixing, collision-induced absorption, and water vapor exhibit noticeable variability across locations and seasons. On the other hand, error estimates due to perturbations in laboratory conditions are nearly constant in space and time.