Low-Level Westerly Winds,Topography, and Tropical Cyclogenesis of Arlene (2005): Observations and Model Simulations |
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| Authors: | Jinwoong Yoo Robert V Rohli Jennifer M Collins |
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| Institution: | 1. Purdue Climate Change Research Center;2. Louisiana State University;3. University of South Florida |
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| Abstract: | The evolution process of the low-level westerly winds over the eastern North Pacific is investigated to understand the tropical cyclogenesis (TCG) of Tropical Storm Arlene (2005) over the Intra-Americas Sea (IAS). Also considered are the influences of the topography of the Central American mountain region interacting with the low-level westerly winds on Arlene's TCG by comparing results from a modified-topography simulation of Arlene's TCG with those from a simulation with the original topography in the Weather Research and Forecast (WRF) model. Interactions among large-scale circulations associated with subtropical highs in both hemispheres and an anticyclone over the warm eastern North Pacific produced low-level westerly winds into the IAS. WRF model experiments with a virtually elevated terrain filling in mountain passes in Central America resulted in the delayed and suppressed development of the incipient storm. The model experiments suggest that the low-level winds and moisture fluxes from the eastern North Pacific passing through the low-level mountain passes in Central America could play a critical role in the TCG process and perhaps also sustenance of storms over the western Caribbean. |
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| Keywords: | Intra-Americas Sea large-scale circulation low-level westerlies orographic effect tropical cyclogenesis |
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