25th Conference on Hurricanes and Tropical Meteorology


Improvements to the NOAA Hurricane Research Division's Surface Reduction Algorithm for Inner Core Aircraft Flight-Level Winds

Jason P. Dunion, NOAA/AOML/HRD and Univ. of Miami/CIAMS, Miami, FL; and M. D. Powell

Recent data from the new Global Positioning System Dropwindsonde (GPS sonde) has provided new insight into the vertical wind structure of Atlantic tropical cyclones. The majority of wind information in the inner core of Atlantic tropical cyclones is provided by Air Force and NOAA reconnaissance aircraft that typically provide flight-level wind data from 700, 850, and 975 hPa. Operational forecasters are faced with the challenge of adjusting these flight-level wind data to equivalent 10 m surface winds in order to determine storm intensity as well as radii of hurricane and gale force winds. The Hurricane Research Division (HRD) has accumulated a database of 300 GPS sondes launched in the inner core of several Atlantic tropical cyclones that has resulted in improvements to HRD's methodology for surface adjusting these flight-level winds. These changes include correcting for tropical cyclone warm core and eyewall tilt effects that can impact vertical wind structure of the inner core as well as accounting for earlier limitations of HRD surface adjustments made in conditions with mean boundary layer winds greater than 55 ms-1. These new aircraft surface reduction methodologies were integrated into HRD's H*Wind surface wind analysis product on an experimental basis during the 2001 Atlantic Hurricane Season.

Session 15A, Tropical Cyclone Observations and Structure IV (Parallel with Sessions 15B and 15D)
Thursday, 2 May 2002, 4:00 PM-5:30 PM

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