DocumentCode :
1447367
Title :
Aerial Radiometric and Video Measurements of Whitecap Coverage
Author :
Bobak, Justin P. ; Asher, William E. ; Dowgiallo, David J. ; Anguelova, Magdalena D.
Author_Institution :
U.S. Naval Res. Lab., Washington, DC, USA
Volume :
49
Issue :
6
fYear :
2011
fDate :
6/1/2011 12:00:00 AM
Firstpage :
2183
Lastpage :
2193
Abstract :
This paper presents the results of high-altitude microwave radiometric and video measurements in the presence of breaking waves made during the passage of Hurricane Dean on August 21, 2007, over the Gulf of Mexico. Previous measurements of foam fraction and radiometric brightness temperature have focused on the small scale, in which individual foam patches were of the same scale as the radiometer footprint. To work with data from spaceborne microwave radiometers, which have footprints on the scale of tens of kilometers, the knowledge of how the foam fraction sensitivity of brightness temperature scales when footprints increase from meters to kilometers is necessary. Video images of the sea surface recorded with a high-resolution monochrome digital camera were used to determine the foam fraction. Ocean-surface brightness temperature was measured with the Airborne Polarimetric Microwave Imaging Radiometer (APMIR) of the Naval Research Laboratory at frequencies of 6.6 [vertical and horizontal (VH) polarizations], 6.8 (VH), 7.2 (VH), and 10.7 GHz (V), with full polarimetric brightness temperatures measured at 19.35 and 37.0 GHz. Collocated nearly contemporaneous brightness temperatures were available from WindSat, Special Sensor Microwave Imager/Sounder, and Special Sensor Microwave/Imager satellite radiometer overpasses. Oceanographic and meteorological data were taken from buoys located along the flight track. There was good correlation between brightness temperatures measured with APMIR and satellite-borne radiometers with absolute differences largely within the expected uncertainty of the data. An analysis of the video imagery provided the fractional area coverage of the actively breaking waves on the ocean surface. The increase in brightness temperature from each of the microwave sensors was correlated with the whitecap coverage measured by the camera. The experiment not only serves as an important bridge between measurements made with spatial scales on the order o f tens of meters and data collected from satellites with spatial scales of tens of kilometers but also provides guidance for improving future field measurements on this topic.
Keywords :
atmospheric boundary layer; ocean temperature; ocean waves; oceanographic techniques; radar polarimetry; radiometry; remote sensing by radar; storms; AD 2001 08 21; APMIR; Airborne Polarimetric Microwave Imaging Radiometer; Hurricane Dean; Mexico gulf; Naval Research Laboratory; Special Sensor Microwave Imager-Sounder; WindSat; aerial radiometric measurements; breaking waves; brightness temperature foam fraction sensitivity; frequency 10.7 GHz; frequency 19.35 GHz; frequency 37.0 GHz; frequency 6.6 GHz; frequency 6.86 GHz; frequency 7.2 GHz; high altitude microwave radiometric measurements; high resolution monochrome digital camera; meteorological data; ocean surface brightness temperature; oceanographic data; polarimetric brightness temperatures; radiometer footprint; radiometric brightness temperature; satellite radiometer overpass; spaceborne microwave radiometers; video measurements; whitecap coverage; Brightness temperature; Calibration; Microwave measurements; Microwave radiometry; Ocean temperature; Sea measurements; Temperature measurement; Foam fraction; microwave radiometry; sea foam; whitecap coverage; wind speed;
fLanguage :
English
Journal_Title :
Geoscience and Remote Sensing, IEEE Transactions on
Publisher :
ieee
ISSN :
0196-2892
Type :
jour
DOI :
10.1109/TGRS.2010.2103565
Filename :
5710975
Link To Document :
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