Hurricane Inner-Core Structure as Revealed by GPS Dropwindsondes

New high-resolution information of the vertical thermodynamic and kinematic structure of the hurricane inner-core is now available from aircraft released Global Positioning System (GPS) dropwindsondes. This is a great technical advancement because now it is possible to sample the inner-core structure of tropical storms in detail. This study presents insights concerning the structure of mature hurricanes from dropwindsonde data obtained during the 1997 and 1998 hurricane seasons. Storm center fixes enable the inner-core calculation of radial and tangential winds. It will be shown that the radial inflow around the eye-wall cloud is approximately twice as large as that determined from frictional forcing. Air sea-surface temperature difference near the surface is in the 3-4 degrees C range, not the 1 degrees C differential previously assumed. Resulting theta(e) values within the eyewall are found to be between 355-360K, which confirms with aircraft observations. The observed vertical gradient of theta(e) in the eyewall region coupled with the inflow greater than expected from frictional forcing, implies an additional physical mechanism for such inflow. It is hypothesized that this additional mechanism is wall cloud buoyancy. Additionally, it is shown that the frictionally driven boundary layer is 1 Km deep. This is determined by the depth of the inflow layer of the radial wind. The vertical gradient of the radial wind within the boundary layer provides insight to the current strength of tropical storms. Further analysis of this dropwindsonde data will lead too improved understanding of the hurricane inner-core region.Air Force Inst of Tech Wright-Patterson AFB OH is the author of 'Hurricane Inner-Core Structure as Revealed by GPS Dropwindsondes', published 2000 under ISBN 9781423551898 and ISBN 1423551893.