The US Air Force routinely fly reconnaissance flights into all tropical and subtropical disturbances within their range. From the temperature and dewpoint information collected during such investigations, the equivalent potential temperature (θe) can be calculated. The data utilized in this research come from all named storms investigated in the period 1995-2002. This yields a total of 67 storms in which there are a total of 551 reconnaissance flights containing usable data.
Composite distributions of θe were determined as a function of radius, altitude and storm intensity. In tropical depressions it was found that θe is nearly constant with radius out to 300km. For tropical storms and hurricanes, θe increases with decreasing radius. The inward radial gradient in θe increases in magnitude for increasing storm intensity. Convective instability is estimated using the vertical gradient of θe in the composites. Tropical storms and category one hurricanes exhibit a structure close to convectively neutral at inner radii, with convective instability becoming greater at larger radii.
The presentation will examine these findings and draw comparisons with related results in published literature.
Session 5D, tropical cyclone observations and structure III
Tuesday, 4 May 2004, 8:00 AM-9:45 AM, Napoleon III Room
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