Saturday, 13 January 2007
WRF model response to physics perturbations during Hurricane Rita
Hurricane Rita made landfall near the Texas-Louisiana border in September 2005, causing major damage and disruption. As Rita approached the Gulf Coast, uncertainties in the track and intensity forecasts of Rita, combined with the aftermath of Hurricane Katrina, led to major evacuations along the Texas coast and significant traffic jams in the broader Houston area. After witnessing Rita and its impacts, several meteorology students at Texas A&M University became interested in investigating Rita's forecasts and societal impacts in greater depth. This led to a student research project; one of the major components is to investigate uncertainties in forecasts of Rita, based on analysis of real-time forecasts and retrospective study using the Weather Research and Forecasting (WRF) model. We are particularly interesting in the WRF forecast sensitivity to using different physics parameterization schemes (as part of model error) and to different forecast lead times (as part of initial condition errors). The WRF model was performed with two different lead times for the forecasted landfall, 60 hours and 72 hours, respectively. It was shown that the lead time when the model was initiated at had a large impact on the intensity and timing of the hurricane. For the 72-h simulations, using combinations of different microphysics, cumulus and planetary boundary layer parameterizations, resulted in very little change in track, but tangible changes in intensity.