CRTM Coefficient Generation to Support Current and Future Satellite Missions

The Community Radiative Transfer Model (CRTM) is a broadband fast radiative transfer model developed through the coordinated efforts of the U.S. Joint Center for Satellite Data Assimilation partners and external research communities. The CRTM is capable of simulating microwave, infrared and visible radiances observed by passive instruments on board spacecraft and aircraft under all-sky conditions. Coupling with the Community Surface Emissivity Model (CSEM), the CRTM is valid over all surface types in a continuous broad spectrum by utilizing either empirical and physical emissivity models or user-specified emissivity. In addition to the forward simulation, CRTM can also be used for the satellite data assimilation by using its tangent-linear, adjoint and K-matrix modules.

Recently, we generated the CRTM Spectral and Transmittance Coefficients to support the CRTM applications in L-Band and Metop-C sensor observations. The NASA/JPL Soil Moisture Active Passive (SMAP) was launched in 2015, and the ESA the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS) on Soil Moisture and Ocean Salinity (SMOS) satellite was launched in 2009. Both radiometers measure all four Stokes parameters at L-band (1.41 GHz), which provide important information of global soil moisture and ocean salinity. To prepare for the coming Metop-C observations, we generated a series of CRTM coefficients for AMSU-A_Metop-C to evaluate the impact of the temperature dependency of SRF. Because of the same instrument design, the IASI_Metop-C coefficient was generated based on that of IASI_Metop-B, with just satellite_ID change. The instrument characteristics, the configurations for the generation, comparison simulations, along with some related developments will be presented.