On Empirical Bias Corrections of NPP CrIMSS OSS Forward Model

The Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS) are two critical sounding instruments onboard the Suomi National Polar-orbiting Partnership (NPP) satellite. CrIS and ATMS collect radiance, with excellent radiometric precision, in the upwelling infrared spectra and microwave spectra respectively. The Cross-track Infrared Sounder and the Advanced Technology Microwave Sounder suite (CrIMSS) Enviromental Data Record (EDR) algorithm converts these radiances using a simultaneous retrieval technique to generate atmospheric vertical profiles of temperature, moisture, and other geophysical parameters. The CrIMSS EDR algorithm employs the forward model of Optimal Spectral Sampling (OSS) model, developed by AER. The OSS model is applied in calculations of both the IR and microwave (MW) radiances. However, because of errors in the forward model calculations due to the instrumental sensitivity to trace gases, uncertainties due to surface emissivity, etc., a bias always exists between the observed and computed radiances. Therefore, the CrIMSS algorithm requires a bias-correction component to account for the differences between the observed radiances and the forward model used in the retrieval algorithm. This work will demonstrate the empirical IR and MW bias corrections of the OSS forward model based on CrIS and ATMS data from the focus day on May 15, 2012. We use ECMWF profiles along with retrieval products and trace-gas climatologies to compute the empirical bias correction. We also confirmed the empirical bias corrections that were done by NASA/LaRC and compared the CrIMSS EDR profiles for (1) empirical bias correction vs. non bias correction, and (2) bias corrected EDRs vs. IDPS EDRs.