A Numerical Study of the Effect of GOES Sounder Cloud-Cleared Brightness Temperatures on the Prediction of Hurricane Felix
FLORIDA STATE UNIV TALLAHASSEE DEPT OFMETEOROLOGY
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The influence of satellite brightness temperature data on the retrospective numerical prediction of Hurricane Felix is investigated. Satellite data are included as an augmentation to bogus data assimilation BDA procedure using a mesoscale adjoint modeling system. Assimilation of satellite brightness temperature data was found to have positive impact on both the intensification and track forecast of the hurricane. The improvements made by the simulations using satellite brightness temperatures were realized by intensifying low-level warm ridge located west of the hurricane, reducing the amount of water vapor below 500 hPa over most areas where satellite data are available, and modifying the structures of the initial vortex in the model initial condition. Although being located over a region devoid of satellite data, the initial vortex obtained using both the satellite and bogus surface low data is more realistic than the one using only the bogus data. Despite the fact that the forecast 3.5 days using only the bogus surface low at the initial time was quite good, track and intensity forecasts beyond 2 days of model integration were shown to be further improved by including satellite data in the initialization procedure. Differences in the prediction of Hurricane Felix with and without satellite data were also found in the prediction of upper-level jet, the cold temperature trough ahead of the hurricane, the size of the hurricane eye, and the location of maximum rainfall during the 3.5 day forecast period. While the focus of this study is to assess the impact of the direct use of satellite brightness temperature data on hurricane prediction, we also noted that the BDA experiment assimilating only the bogus data shows a positive impact of the BDA generated hurricane on the environmental flow, as verified by satellite observations.