Application of SSM/I satellite data to a hurricane simulation

The impact of Special Sensor Microwave/Imager (SSM/I) data on simulations of hurricane Danny is assessed. The assimilation of SSM/I data is found to increase the atmospheric moisture content over the Gulf of Mexico, strengthen the low-level cyclonic circulation, shorten the model spin-up time, and significantly improve the simulation of the storm's intensity. Two different approaches for assimilating SSM/I data, namely assimilating retrieved products and assimilating raw measurements, are further compared. The data-assimilation analyses from these two approaches give different moisture distributions in both the horizontal and vertical directions in the storm's vicinity, which may potentially affect the simulated storm's development; however, the simulated storm intensities are considered comparable for the Danny case. From sensitivity tests performed in this study, it is also found that the choice of the observational error variances could be potentially important to the model simulations.