DocumentCode :
59717
Title :
Cross-Calibration Between QuikSCAT and Oceansat-2
Author :
Jaruwatanadilok, Sermsak ; Stiles, Bryan W. ; Fore, Alexander G.
Author_Institution :
Jet Propulsion Lab., Pasadena, CA, USA
Volume :
52
Issue :
10
fYear :
2014
fDate :
Oct. 2014
Firstpage :
6197
Lastpage :
6204
Abstract :
This paper presents the procedure to perform cross-calibration of radar backscatter between the QuikSCAT and Oceansat-2 ocean wind scatterometers. Both QuikSCAT and Oceansat-2 are Ku-band dual pencil beam, rotating antenna scatterometers with similar design. There has been a joint effort by the Indian Space Research Organization, NASA, KNMI, and NOAA to perform calibration and validation of Oceansat-2 in order to extend the climate data record of ocean surface vector winds obtained by QuikSCAT. This has resulted in significant improvement in the quality of the normalized radar cross section (NRCS) data and the quality of the resultant winds produced using the Oceansat-2 NRCS measurements. An important aspect of this calibration is the reduction of the calibration bias between QuikSCAT and Oceansat-2. The nonspinning QuikSCAT scatterometer was repointed to achieve the same incidence angles for its two HH and VV polarized antenna beams as those utilized by Oceansat-2. The magnitudes of the NRCS (backscatter) measurements of the two scatterometers were then compared for two years in order to determine NRCS bias in decibels as a function of time. Biases for both antenna beams were computed. A wind speed/wind-relative azimuth angle histogram-matched method was applied to ocean data from the two scatterometers to determine the time series of the bias between the two. It has been determined that there was an ~0.5 dB drop in Oceansat-2 radar backscatter on August 20, 2010. As a result, we compute cross-calibration adjustments to apply to Oceansat-2 data before and after this distinct drop in backscatter.
Keywords :
atmospheric boundary layer; atmospheric measuring apparatus; atmospheric techniques; backscatter; calibration; oceanography; radar antennas; remote sensing by radar; wind; AD 2010 08 20; HH polarized antenna beams; Indian Space Research Organization; KNMI; Ku-band scatterometers; NASA; NOAA; NRCS data; QuikSCAT-Oceansat-2 cross calibration; VV polarized antenna beams; calibration bias reduction; climate data record; dual pencil beam scatterometers; nonspinning QuikSCAT scatterometer; normalized radar cross section; ocean surface vector winds; ocean wind scatterometers; radar backscatter cross calibration; rotating antenna scatterometers; wind relative azimuth angle histogram matched method; wind speed matched method; Azimuth; Backscatter; Calibration; Noise; Sea measurements; Sensors; Wind speed; Calibration; Oceansat-2; QuikSCAT; scatterometer;
fLanguage :
English
Journal_Title :
Geoscience and Remote Sensing, IEEE Transactions on
Publisher :
ieee
ISSN :
0196-2892
Type :
jour
DOI :
10.1109/TGRS.2013.2295539
Filename :
6712050
Link To Document :
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