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Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at LandfallThe sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1' half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the off-nadir angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving toward 330 deg at about 5 m/s. Individual waves up to 18 m height were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the eye, and made five eye penetrations. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft flight lines included segments near and along the shoreline as well as far offshore. Animations of the directional wave spectrum spatial variation along the aircraft tracks on the two flights will be presented using a 100: 1 time compression.
Document ID
20000083900
Acquisition Source
Wallops Flight Facility
Document Type
Conference Paper
Authors
Walsh, Edward J.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Wright, C. Wayne
(NASA Wallops Flight Facility Wallops Island, VA United States)
Vandemark, Douglas C.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Krabill, William B.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Garcia, Andrew W.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Houston, Samuel H.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Powell, Mark D.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Black, Peter G.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Marks, Frank D.
(NASA Wallops Flight Facility Wallops Island, VA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: IGARSS 2000
Location: Honolulu, HI
Country: United States
Start Date: July 24, 2000
End Date: July 28, 2000
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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