Enhanced Quality Control with the NSCAT-5 Geophysical Model Function

• Main Authors: Portabella, Marcos, Lin, Wenming, Stoffelen, Ad, Verhoef, Anton, Wang, Zhixiong
• Other Authors: Ocean and Sea Ice Satellite Application Facility
• Format: Report
• Language: English
• Published: EUMETSAT 2019
• Subjects: Indian; Sea ice
• Online Access: http://hdl.handle.net/10261/257138

24 pages, 10 figures, 2 tables Recent developments on the wind geophysical model function (GMF) of Ku-band scatterometers include a sea surface temperature (SST) dependent term. It has been found that the SST effects on the radar backscatter are wind speed dependent and more pronounced in vertical polarization (VV) than in horizontal polarisation (HH) at higher incidence angles, and are mainly relevant at Ku radar wavelengths rather than at C-band. The new Ku-band GMF, NSCAT-5, was initially based on a physical model and RapidScat radar backscatter measurements, which are only available at two incidence angles, i.e., 48.8⁰ and 55.2⁰, for HH and VV beams, respectively. A more recent CDOP-2 AS study (OSI_AVS_17_01) confirms only small differences when verify ing the NSCAT-5 GMF at similar incidence angles, using data from the recently-launched Indian SCATSat-1, which operates at 49.1⁰ (HH) and 57.9⁰ (VV) incidence angle. In order to further consolidate the NSCAT-5 GMF, the current study looks for quality control (QC) dependencies. It is found that indeed, the developed GMF is not particularly sensitive to different QC thresholds. Finally, an improved QC method, based on the successful experience with previous Ku-band rotating pencil-beam scatterometers, is developed for SCATSat-1 data The work has been funded under the EUMETSAT Ocean and Sea Ice (OSI) Satellite Application Facility (SAF) Associated Scientist project (reference OSI_AVS_17_04) Peer reviewed