Extended Abstract (436K)P1.30
Saharan Air Layer interaction with Hurricane Claudette (2003)
Gabriel S. Rothman, Texas Tech University, Lubbock, TX; and C. -. B. Chang and T. E. Gill
On June 29, 2003, an easterly wave embedded in a broad Saharan dust layer emerged from the West African Coastal Bend region into the Atlantic Ocean. The wave propagated westward, reaching tropical storm intensity as Claudette in the Caribbean and further developed into a hurricane just before making landfall on the Southern Texas Gulf of Mexico Coast on July 15. The Saharan Air Layer(SAL) and the associated dust outbreak propagated in phase with this wave throughout its entire evolution. In order to understand the physical nature of the SAL-wave interaction that took place in this case, a comprehensive diagnosis is performed utilizing dynamical and thermodynamical parameters as well as the MODIS Aqua Satellite cloud product derived from channels 29 and 31 through 36(shortwave infrared bands). The diagnostic part of the study utilizes NOGAPS 0.5 degree model initialization data. The diagnosis focuses on several possible associated features of the SAL and their interactions with Claudette and its predecessor wave throughout its evolution in the Atlantic and how these play a role in the modulation of convection. These features include the associated Mid-Level Easterly Tropical Jet (MLEJ) and the potential temperature gradient boundaries that define the SAL. A sensitivity study is also conducted to quantify the variation of tropical cyclone intensity due to the Saharan dust layer optical depth and the storm environmental genesis parameters. All data in the sensitivity study are evaluated at the center of the wave axis or low-level inner vortex. A partial correlation analysis evaluates the variations of the storm environmental genesis parameters caused by the Saharan dust layer. In this case, the storm environmental genesis parameters being considered include the 850 mb-250 hPa wind shear vector, 950 hPa equivalent potential temperature, 500 hPa mixing ratio, sea surface temperature, 700 hPa potential temperature and 200 hPa relative vorticity.
Poster Session 1, Posters
Wednesday, 5 May 2004, 1:30 PM-1:30 PM, Richelieu Room
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