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Webinar: Enhancing all-sky radiative transfer calculations for the assimilation of microwave observations
Wednesday, 25 January 2023, 12:00
Wednesday. January 25, 2023. 12:00 PM. Webinar: Enhancing all-sky radiative transfer calculations for the assimilation of microwave observations. Isaac Moradi, University of Maryland. Sponsored by NOAA JPSS. More information here. Register here.
Community Radiative Transfer Model (CRTM) is widely used in the United States for the assimilation of satellite observations into NWP models. All-sky data assimilations systems rely on radiative transfer cloud scattering database for simulating all-sky observations from input profiles provided by the NWP model. The Mie theory is used by many fast RT models to estimate the optical properties of single particles. The Mie theory assumes spherical shapes for ice or snow particles with mixture of air and ice. However, hydrometeors scattering radiation at microwave frequencies have different shapes, sizes, and orientations. Therefore, using Mie theory to determine their optical properties leads to large uncertainties in all-sky radiative transfer calculations. The discrete dipole approximation (DDA) which approximates the optical properties of large objects in terms of discrete dipoles has shown promises in calculating the scattering properties of particles with different shapes in the microwave frequencies. The goal of the research is to enhance the CRTM scattering calculations for frozen hydrometeors in the microwave frequencies using the DDA technique. In addition to using stand-alone CRTM calculations using collocated ATMS and reanalysis profiles, the data assimilation experiments conducted using the NOAA FV3GFS forecast system will be used to evaluate the scattering improvements.