Keywords
atmospheric techniques, calibration, electromagnetic wave scattering, geophysical techniques, meteorological radar, oceanographic techniques, radar applications, radar cross-sections, remote sensing by radar, spaceborne radar, wind
Abstract
Wind scatterometers are radar systems designed specifically to measure the normalized radar backscatter coefficient (O) of the ocean's surface in order to determine the near-surface wind vector. Postlaunch calibration of a wind scatterometer can be performed with an extended-area natural target such as the Amazon tropical rain forest. Rain forests exhibit a remarkably high degree of homogeneity in their radar response over a very large area though some spatial and temporal variability exist. The authors present a simple technique for calibrating scatterometer data using tropical rain forests, Using a polynomial model for the rolloff of O with incidence angle, the technique determines gain corrections to ensure consistency between different antennas and processing channels. Corrections for the time varying instrument gain are made consistent with a seasonally fixed rain forest response; however, without ground stations or aircraft flights, it is difficult to uniquely distinguish between seasonal variations in the rain forest and slow variations of the system gain. Applying the corrections, the intrinsic variability of the O of the rain forest is estimated to be ±0.15 dB, which is the limit of the accuracy of calibration using the rain forest. The technique is illustrated with Seasat scatterometer (SASS) data and applied to ERS-1 Active Microwave Instrument scatterometer (Escat) data. Gain corrections of up to several tenths of a decibel are estimated for SASS. Corrections for Escat data are found to be very small, suggesting that Escat data is well calibrated.
Original Publication Citation
Long, D. G., and G. B. Skouson. "Calibration of Spaceborne Scatterometers using Tropical Rain Forests." Geoscience and Remote Sensing, IEEE Transactions on 34.2 (1996): 413-24
BYU ScholarsArchive Citation
Long, David G. and Skouson, Gary B., "Calibration of spaceborne scatterometers using tropical rain forests" (1996). Faculty Publications. 681.
https://scholarsarchive.byu.edu/facpub/681
Document Type
Peer-Reviewed Article
Publication Date
1996-03-01
Permanent URL
http://hdl.lib.byu.edu/1877/1026
Publisher
IEEE
Language
English
College
Ira A. Fulton College of Engineering and Technology
Department
Electrical and Computer Engineering
Copyright Status
© 1996 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
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