Impact of Atmospheric and Ocean Initial Conditions on the Intensity Prediction of Hurricane Katrina with the GFDL Hurricane Model

The GFDL coupled regional hurricane model provided operational guidance for Hurricane Katrina in 2005. Although the track guidance was outstanding from the August 27th, 00 UTC synoptic time up to the period of landfall, the version of the model run operationally at the time was unable to predict the rapid intensification of Katrina once it moved into the Eastern Gulf of Mexico. One of the contributing factors to the under prediction of the intensity of this hurricane was inadequate representation of the Loop Current in the ocean model. Subsequent upgrades to the GFDL model since 2005 have included the capabilities of assimilating real-time sea surface height satellite measurements for more realistic ocean model initialization. Recent analysis has shown that the storm size of Hurricane Katrina was also underestimated in the GFDL initial condition. In this study, we have conducted sensitivity experiments with the 2015 version of the GFDL operational hurricane to evaluate the impact of atmospheric and ocean initial conditions on the intensity prediction of Hurricane Katrina. It is shown that with more accurate representation of the Loop Current in the Gulf of Mexico and storm size the rapid intensification of Katrina could be more accurately predicted in the new version of the GFDL model. These results demonstrate the critical role these two parameters played in Katrina's intensity and suggest that accurate representation of both is critical in predicting hurricane intensity with regional models.

Disclaimer: The views, opinions, and findings contained in this report are those of the authors and should not be construed as an official National Oceanic and Atmospheric or U.S. government position, policy, or decision