CRTM Improvement toward the Assimilation of SW IR Radiances

To assimilate the shortwave (SW, 4.1–4.5um) radiances into numerical weather prediction models. The effect of non-Local Thermodynamic Equilibrium (non-LTE) process needs to be accurately represented in the forward operator. The non-LTE emission may contribute up to 10K to the satellite measured brightness temperature in the CO2 4.3um band. The Community Radiative Transfer Model (CRTM) used in current NOAA Global Data Assimilation System corrects the non-LTE effect with a regression model. In this study, an upgrade of the CRTM non-LTE correction will be obtained based on the revised vibrational temperature profiles from Jurado-Navarro, et al. (2015) and simulations using the latest version of Community Line-by-Line Model or the Line-by-Line Radiative Transfer Model (CLBLM/LBLRTM). The improvement will be discussed in comparison with the Cross-track Infrared Sounder (CrIS) measurement under different conditions (various solar illuminations, seasons, and latitude locations, etc.).