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- Title
Retrieving hurricane wind speeds using cross-polarization C-band measurements.
- Authors
van Zadelhoff, G.-J.; Stoffelen, A.; Vachon, P. W.; Wolfe, J.; Horstmann, J.; Belmonte Rivas, M.
- Abstract
Hurricane-force wind speeds can have a large societal impact and in this paper microwave C-band cross-polarized (VH) signals are investigated to assess if they can be used to derive extreme wind-speed conditions. European satellite scatterometers have excellent hurricane penetration capability at C-band, but the vertically (VV) polarized signals become insensitive above 25ms-1. VV and VH polarized backscatter signals from RADARSAT-2 SAR imagery acquired during severe hurricane events were compared to collocated SFMR wind measurements acquired by NOAA's hurricane-hunter aircraft. From this data set a geophysical model function (GMF) at strong-to-extreme/severe wind speeds (i.e., 20ms-1 <U10 <45 ms-1) is derived. Within this wind speed regime, cross-polarized data showed no distinguishable loss of sensitivity and as such, cross-polarized data can be considered a good candidate for the retrieval of strong-to-severe wind speeds from satellite instruments. The upper limit of 45ms-1 is defined by the currently available collocated data. The validity of the derived relationship between wind speed and VH backscatter has been evaluated by comparing the cross-polarized signals to two independent wind-speed data sets (i.e., short-range ECMWF numerical weather prediction (NWP) model forecast winds and the NOAA best estimate 1-minute maximum sustained winds). Analysis of the three comparison data sets confirm that cross-polarized signals from satellites will enable the retrieval of strong-to-severe wind speeds where VV or horizontal (HH) polarization data has saturated. The VH backscatter increases exponentially with respect to wind speed (linear against VH[dB]) and a near-real-time assessment of maximum sustained wind speed is possible using VH measurements. VH measurements thus would be an extremely valuable complement on next-generation scatterometers for hurricane forecast warnings and hurricane model initialization.
- Subjects
WIND speed; BACKSCATTERING; UNITED States. National Oceanic &; Atmospheric Administration; HURRICANE forecasting; HURRICANE modification
- Publication
Atmospheric Measurement Techniques, 2014, Vol 7, Issue 2, p437
- ISSN
1867-1381
- Publication type
Article
- DOI
10.5194/amt-7-437-2014