The Joint Center for Satellite Data Assimilation (JCSDA) Community Radiative Transfer Model (CRTM) is a fast, 1-D radiative transfer model used across multiple federal agencies and universities for numerical weather prediction, retrievals of environmental data records, remote sensing data calibration/validation, and many other applications. The key benefit of the CRTM is that it can interpret and utilize electromagnetic signals from satellite measurements for acquiring geophysical information such as atmospheric profiles of temperature and moisture, clouds, precipitation, and aerosols as well as various gaseous constituents. CRTM covers the spectral ranges consistent with all present operational and most research environmental satellites, from visible to microwave.  The capability to simulate/assimilate ultraviolet radiances and fully polarized radiances are being added over the next year.

Another unique aspect of the CRTM is that it also provides the tangent-linear, adjoint, and Jacobian outputs needed for satellite radiance assimilation and retrieval applications. The ability to compute a Jacobian for various geophysical input parameters significantly expands the capabilities beyond traditional forward RT models, such as those used in remote sensing retrieval algorithms and other "Bayesian" or "1D-VAR" applications. The adjoint and Jacobian techniques also dramatically shorten computational times, about one thousand times faster than finite difference methodology using traditional forward RT models. 

In this presentation, I will focus on recent efforts to improve the ability of the CRTM to accurately simulate precipitation-impacted radiances and associated jacobians, for both passive and active instruments, and will provide an demonstration and discussion of the impact of these improvements within a data assimilation framework.