An Ocean Wind Doppler Model Based on the Generalized Curvature Ocean Surface Scattering Model

Type Article
Date 2015-12
Language English
Author(s) Said Faozi1, Johnsen Harald2, Chapron Bertrand3, Engen Geir2
Affiliation(s) 1 : NOAA, Ocean Surface Winds Team, Ctr Satellite Applicat & Res, College Pk, MD 20740 USA.
2 : Norut, Earth Observat Grp, N-9294 Tromso, Norway.
3 : IFREMER, Lab Oceanog Space, F-29280 Brest, France.
Source Ieee Transactions On Geoscience And Remote Sensing (0196-2892) (Ieee-inst Electrical Electronics Engineers Inc), 2015-12 , Vol. 53 , N. 12 , P. 6632-6638
DOI 10.1109/TGRS.2015.2445057
Keyword(s) Doppler measurements, geophysical measurement techniques, sea surface, synthetic aperture radar (SAR)
Abstract A Doppler centroid D-C model based on the generalized curvature ocean surface scattering model (generalized curvature model or GCM) is presented. Two key features are included in this model: a skewness-related phase coefficient based on empirical skewness coefficients of sea-surface-slope probability density function (pdf) for wind speed less than 10 m/s and effects from wave breaking for wind speed greater than 10 m/s. Simulated D-c values are exclusively compared with the empirical geophysical Doppler model function named CDOP, for hh and vv polarizations, various wind conditions, and incidence angles. Good agreement is found overall between CDOP and simulated D-C values. The overall bias for simulated Dc-vv with and without skewness are 2.63 versus -0.51 Hz (14.6 versus -2.8 cm/s), respectively; overall standard deviations are 2.76 versus 3.53 Hz (15.3 versus 19.6 cm/s). For simulated DC-hh, overall bias values with and without skewness are -0.16 versus -2.52 Hz (-0.9 versus -14 cm/s); standard deviations are 3.56 versus 4.32 Hz (19.7 versus 24 cm/s). The overall bias for simulated Dc-vv with and without the wave breaking component are -0.08 versus 0.12 Hz (-0.4 versus 0.7 cm/s), respectively; corresponding standard deviations are 3.32 versus 4.75 Hz (18.4 versus 26.3 cm/s). Bias values for simulated Dc-vv with and without the wave breaking component are -1.83 versus -2.02 Hz (-10.2 versus -11.2 cm/s), with corresponding overall standard deviations of 3.43 versus 4.87 Hz (19 versus 27 cm/s). The largest deviation from CDOP, of about 18 Hz (0.99 m/s), is found in the upwind direction for a 26 incidence angle, 10-m/s wind speed, and hh polarization.
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