Compact Polarimetry Synthetic Aperture Radar Ocean Wind Retrieval: Model Development and Validation

Type Article
Date 2021-04
Language English
Author(s) Zhang Biao1, 2, 3, Lu Yiru1, Perrie William3, Zhang Guosheng1, 2, Mouche AlexisORCID4
Affiliation(s) 1 : Nanjing Univ Informat Sci & Technol, Sch Marine Sci, Nanjing, Peoples R China.
2 : Southern Marine Sci & Engn Guangdong Lab Zhuhai, Zhuhai, Peoples R China.
3 : Fisheries & Oceans Canada, Bedford Inst Oceanog, Dartmouth, NS, Canada.
4 : Univ Brest, Lab Oceanog Phys & Spatiale, CNRS, IFREMER,IRD, Brest, France.
Source Journal Of Atmospheric And Oceanic Technology (0739-0572) (Amer Meteorological Soc), 2021-04 , Vol. 38 , N. 4 , P. 747-757
DOI 10.1175/JTECH-D-20-0035.1
WOS© Times Cited 4
Keyword(s) Ocean, Wind, Algorithms, Remote sensing

We have developed C-band compact polarimetry geophysical model functions for RADARSAT Constellation Mission ocean surface wind speed retrieval. A total of 1594 RADARSAT-2 images acquired in quad-polarization SAR imaging mode were collocated with in situ buoy observations. This dataset is first used to simulate compact polarimetric data and to examine their dependencies on radar incidence angle and wind vectors. We find that right circular transmit, right circular receive (RR-pol) radar backscatters are less sensitive to incidence angles and wind directions but are more dependent on wind speeds, compared to right circular transmit, horizontal receive (RH-pol), right circular transmit, vertical receive (RV-pol), and right circular transmit, left circular receive (RL-pol). Subsequently, the matchup data pairs are used to derive the coefficients of the transfer functions for the proposed compact polarimetric geophysical model (CMOD) functions, and to validate the associated wind speed retrieval accuracy. Statistical comparisons show that the retrieved wind speeds from CMODRH, CMODRV, CMODRL, and CMODRR are in good agreement with buoy measurements, with root-mean-square errors of 1.38, 1.51, 1.47, and 1.25 m s(-1), respectively. The results suggest that compact polarimetry is a good alternative to linear polarization for wind speed retrieval. CMODRR is more appropriate to retrieve high wind speeds than CMODRH, CMODRV or CMODRL.

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