Predicted errors of tropospheric emission spectrometer nadir retrievals from spectral window selection

Abstract

Error covariances and vertical resolutions are reported for Tropospheric Emission Spectrometer (TES) nadir‐view retrievals of surface temperature, atmospheric temperature, H 2 O, O 3 , CO, and CH 4 . These error covariances are computed as a result of selecting spectral windows that maximize the information content of simulated, TES nadir‐view atmospheric retrievals of four regions representative of northern midlatitude, southern midlatitude, tropical, and polar climates. The information content of a retrieval is a function of an a priori and an a posteriori covariance matrix where the a posteriori covariance depends on an estimated smoothing error, measurement error, and systematic errors from interfering species, surface emissivity, atmospheric and surface temperature, and line parameter uncertainties. For conditions representative of northern midlatitudes, we can expect about 3 degrees of freedom (DOF) for retrievals of H 2 O, 5 DOF for O 3 with about 2.4 DOF in the troposphere, and 0.8 DOF for CO. These measures for the vertical resolution and the predicted errors can be used to assess which atmospheric science questions can be addressed with TES atmospheric retrievals. Proper characterization of TES retrievals is also critical for applications such as atmospheric data assimilation and inverse modeling.