A methodology of cross-comparison of C-band spaceborne scatterometers is developed and applied to ERS-1 and ERS-2 scatterometers data. Assuming the differences between the instruments can be represented by an incidence-angle dependent bias, this paper presents and discusses four methods providing an estimate of that bias and of its standard deviation. These methods use natural distributed targets such as rainforest, ocean and sea ice, and are based on geophysical model functions, namely constant gamma model, CMOD5 and sea ice line model. The backscatter from the natural distributed targets is compared against a simulated backscatter providedby the models. Finally, the deviation of the two datasets from the models are comparedto yield a bias between the two scatterometers. The methodologyis applied to ERS-1 and ERS-2 data acquired during the tandem mission in 1996. Generally, the bias between the ERS-1 and ERS-2 scatterometers is smaller than 0.2 dB over most incidence angles and the four methods provide relatively consistent results. However, in order to achieve a consistent backscatter data, the scatterometers need to be inter-calibrated. The methodology can be useful to cross-calibrate scatterometers on-board other satellites (e.g. METOP, OceanSat-2, HY2A, etc.) in the view of the Global Climate Observing System guidelines.

Date Published: 19 October 2012
PDF: 9 pages
Proc. SPIE 8532, Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2012, 85320O (19 October 2012); doi: 10.1117/12.975218

Published in SPIE Proceedings Vol. 8532:
Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2012
Charles R. Bostater Jr.; Stelios P. Mertikas; Xavier Neyt; Caroline Nichol; Dave Cowley; Jean-Paul Bruyant, Editor(s)