Upper ocean response and feedback to 2002 Hurricanes Isidore and Lili in tandem
Wei Zhao, Univ. of Miami/RSMAS, Miami, FL; and S. S. Chen and J. Tenerelli
Hurricane passage over ocean represents one of the most extreme atmospheric forcing events of the upper ocean because of the large heat and momentum fluxes. Upper ocean response to a single hurricane had been studied previously using both observations and numerical methods. During the 2002 hurricane season, Hurricanes Isidore and Lili propagated through the Gulf of Mexico following each other in a similar track only a week apart. This tandem hurricane event provides a rare opportunity to study the upper ocean response to the complex atmospheric forcing. The objective of this study is to investigate the upper ocean response to the two hurricanes and its potential impact on hurricane intensity changes. In this study, two different ocean models are used to examine the upper ocean response to the hurricane forcing. One is the full physics Hybrid Coordinate Ocean Model (HYCOM) and the other is the relatively simple Price-Weller-Pinkel (PWP) upper ocean model. Both ocean models are forced by a very high resolution (~1.67 km) atmospheric model simulations of Hurricanes Isidore and Lili, in which the extreme high winds and strong pressure gradients associated with the hurricane eyewall are explicitly resolved. The model results are compared with observations. The PWP model has been used to study the upper ocean response to hurricane forcing in several studies. The difference in the upper ocean response from the simple PWP model and HYCOM is investigated. And the upper ocean response to the two hurricanes, includes thermal structure, current pattern and mixing, are described. Furthermore, to test the sensitivity of upper ocean response to the atmospheric forcing, a set of experiments using various model resolution in the atmospheric model is conducted. The results indicate that higher resolution atmospheric forcing has a significant impact on the upper ocean response to hurricanes. These ocean model results will be tested in a coupled atmospheric-ocean model to study the impact of upper ocean on hurricane intensity changes.
Extended Abstract (332K)
Session 16A, sea-air interaction: Hurricanes Isidore and Lili
Friday, 7 May 2004, 8:00 AM-9:45 AM, Le Jardin Room
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