Extended Abstract (1.6M)9B.4
Understanding the genesis of Hurricane Vince through the surface pressure tendency equation
Kwan-yin Kong, Hydrometeorological Prediction Center, Camp Springs, MD
Hurricane Vince was one of the many extraordinary hurricanes that formed in the record-breaking 2005 Atlantic hurricane season. Unlike Katrina, Rita, and Wilma, Vince was remarkable not because of intensity, nor the destruction it inflicted, but because of its defiance to our current understandings of hurricane formation. Vince formed in early October of 2005 in the far North Atlantic Ocean and acquired characteristics of a hurricane southeast of the Azores, an area previously unknown to hurricane formation. Buoys located near the track of the hurricane indicated sea-surface temperatures as low as 22.5°C, far below what is considered to be the minimum value of 26°C for hurricane formation. In March of 2004, a first-documented hurricane in the South Atlantic Ocean also formed over SST below this 26°C threshold off the coast of Brazil. In addition, cyclones in the Mediterranean and polar lows in sub-arctic seas had been observed to acquire hurricane characteristics. These cyclones, like typical tropical cyclones, are apparently warm core in structure, and apparently energized by convection. The formation of these cyclones over anomalously low SST motivates us to re-examine our basic understandings of hurricane genesis and intensity change. Based on the hydrostatic and thermodynamic equations, a pressure tendency equation has been derived. This new equation reveals a direct mathematical link of temperature advection, static stability, vertical motion, and diabatic heating, to the surface pressure tendency. This surface pressure tendency equation proves to be particularly revealing with regard to the dynamics of hurricane formation and intensification.
Session 9B, Tropical Cyclogenesis I
Wednesday, 26 April 2006, 1:30 PM-3:00 PM, Regency Grand Ballroom
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