The VIIRS Fast Radiative Transfer Model (VFRTM)

We present the Visible/Infrared Imager Radiometer Suite (VIIRS) Fast Radiative Transfer Model (VFRTM), a computationally efficient package for simulating VIIRS radiances and reflectances. The VFRTM combines several optimizations for plane parallel radiative transfer in cloudy atmospheres, including precomputed look-up tables for water and ice cloud properties and correlated-k distributions for gas absorption. These advances have been documented in a series of papers describing the longwave (Wang et al., 2011, JAMC) and shortwave radiative transfer algorithms (Wang et al. 2013, JQSRT; Liu et al., 2015 JGR Atmospheres). The VFRTM combines these methods into a single package that can simulate all VIIRS bands usable for cloud property retrievals. We also include the capability to simulate a channel, constructed from a fusion of VIIRS and CrIS data, similar to MODIS band 33 at 13.3 µm wavelength (Cross et al., 2013 JARS). The VFRTM can be used as a stand-alone compiled executable with input text configuration files, or as a library from fortran or python programs. The software and example test cases will be available for download from the Space Science and Engineering Center (SSEC) website.