Abstract:The Cross-track Infrared Sounder (CrIS) hyperspectral infrared (IR) sensor has three bands that are used for remote sensing: a longwave (LW) band from 650 - 1095 cm-1, a midwave (MW) band from 1210 - 1750 cm-1, and a shortwave (SW) band with wavenumbers covering 2155 - 2550 cm-1. In the NOAA operational Global Data Assimilation System (GDAS), only CrIS LW channels and a small number of CrIS MW channels from a subset of 431 CrIS full spectral resolution (FSR) channels are actively assimilated. Work at NOAA/NESDIS/STAR and University of Maryland CISESS has been aimed at evaluating the use of CrIS SW observations in the GDAS and Finite-Volume Cubed-Sphere Global Forecast System (FV3GFS) from the 431 channel set in SW-only and LW plus SW configurations. Initial findings suggest that the assimilation of CrIS SW observations, with the implementation of new CrIS SW-specific quality controls and scene-dependent observation errors, can produce a beneficial impact on FV3GFS forecasts when compared to the assimilation of only the CrIS LW and few MW channels normally used in operational forecasting.
The work at NOAA/NESDIS/STAR to assimilate CrIS SW observations is ongoing, and has not been without challenges. To be discussed are what has been done so far, what we have learned from initial results from experiments assimilating CrIS SW channels, what we are still working on, and the direction(s) we would like to take in future efforts.
