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| Titel |
Retrieving hurricane wind speeds using cross-polarization C-band measurements |
| VerfasserIn |
G.-J. van Zadelhoff, A. Stoffelen, P. W. Vachon, J. Wolfe, J. Horstmann, M. Belmonte Rivas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 2 ; Nr. 7, no. 2 (2014-02-07), S.437-449 |
| Datensatznummer |
250115596
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| Publikation (Nr.) |
 copernicus.org/amt-7-437-2014.pdf |
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| Zusammenfassung |
| 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
25 m s−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., 20 m s−1 < U10 < 45 m s−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 45 m s−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. |
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