SSEC/CIMSS at the University of Wisconsin-Madison is tasked with testing and developing the forward radiative transfer model and retrieval algorithms for the next generation of geostationary sounders, including the Hyperspectral Environmental Sounder (HES) and the Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS). In support of this work, numerical model simulations with high spatial and temporal resolution are used to produce a "truth" atmosphere, which is then passed through the instrument forward model to generate simulated top of the atmosphere radiances. Retrievals of temperature, water vapor and winds generated from these radiances are subsequently compared with the original simulated atmosphere to assess retrieval accuracy.

In this paper, we present a comparison of simulated top of atmosphere radiance datasets derived from high-resolution (4-km) MM5 and WRF numerical simulations of a major tornado outbreak that occurred over the Northern Plains on 24 June 2003. This comparison will allow us to assess the ability of each model to realistically simulate the fine-scale horizontal and vertical structure commonly evident in the water vapor field. Preliminary results indicate that the WRF-simulated atmospheric and microphysical fields qualitatively possess more spatial variability than the MM5 simulated fields. This improved spatial variability is most likely due to the improved numerical schemes in the WRF model that are more appropriate at such finely resolved scales than those present in the MM5. The ability of the WRF model to produce atmospheric fields with greater spatial variability than the MM5 indicates that it is more appropriate to use the WRF model to generate the numerical simulations used to produce the simulated radiance datasets.