Extended Abstract (168K)P1.88
A simulation of hurricane Isidore (2002) using MM5
Diana Pozo, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico; and I. Borrajero and G. B. Raga
Tropical Storm Isidore reached hurricane category on 19 September 2002. It made landfall near Cabo Frances in western Cuba on 20 September, with maximum observed winds of 75 knots. It remained over land for about 12 hours and then proceeded westward towards the Yucatan peninsula in Mexico. Over warm waters (maximum SST of 30 C) the storm rapidly intensified to a category 3 hurricane, in the 400km that separate Cuba from the site in the Yucatan peninsula where it made landfall. Its central pressure dropped from 965 mb upon leaving Cuba to 934 mb just before landfall, in the northern coast of Yucatan. Over Mexico the storm lingered for over 30 hours and the high winds and torrential rains caused major disruptions that lasted a few weeks after passage. The motivation of this study is to gain insight on the processes that led to the intensification of the storm between western Cuba and the Yucatan peninsula.
We have implemented the mesoscale meteorological model MM5 (Penn State-NCAR) for the region of interest utilizing 3 nested domains. The innermost domain had a resolution of 10km in the horizontal, which is moderately high and would allow a detailed study of the physical processes leading to intensification. Data from AVN were used to initialize the simulation over Cuba at 00 UTC on 21 September. The simulation was carried out for 48 hours, with data assimilation implemented every 6 hours.
The simulated storm developed a coherent eye and followed a westward trajectory, resulting in a maximum difference between simulated and observed tracks of approximately 150 km, while landfall in the model occurred about 1.5 hours after actual landfall. The central pressure reached 942mb, about 8mb higher than the "best track minimum pressure" observations. The simulated hurricane had asymmetric rainbands, mainly precipitating in the SE quadrant. The model was used with the surface flux parameterization of Blackadar. We are currently investigating the sensitivity of the minimum pressure to a modified parameterization of the latent heat flux at the ocean surface, considering the drag coefficient as a function of the wind speed.
Poster Session 1, Posters
Wednesday, 5 May 2004, 1:30 PM-1:30 PM, Richelieu Room
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