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Pier‐based observations of polarized sea surface emission
Author(s) -
Frasier S. J.,
Wang F.,
Carswell J. R.,
Knapp E. J.,
Swift C. T.
Publication year - 2001
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2000rs002333
Subject(s) - azimuth , brightness temperature , scatterometer , physics , geology , wind speed , geodesy , radar , geometry , meteorology , brightness , optics , mathematics , telecommunications , computer science
A Ka band polarimetric radiometer operating at 37 GHz was deployed from the seaward end of a small pier colocated with an X band Doppler scatterometer used to measure the instantaneous wave field. Brightness temperature time series from a small spot on the surface for four linear polarizations were measured: T V , T H , T P , and T M , corresponding to vertical, horizontal, +45°, and −45°, respectively. Expected behavior of the mean values of T V and T H was observed as a function of incidence and azimuth angles. Varying sensitivities to the wave field in T P and T M were observed as a function of azimuth angle with respect to the upwind direction. To the left of upwind, wave‐induced modulations of T P exceeded those of T M , while the opposite behavior was observed to the right of upwind. Since U is the mean value of the difference of these signals, it is relatively easy to interpret the sine variation of U with wind‐relative azimuth angle. Finally, modulations of brightness temperatures by the wave field were found to be consistent with the “smoothed” slope distribution provided by the radar.