An L-band geophysical model function for SAR wind retrieval using JERS-1 SAR

Teruhisa Shimada, Hiroshi Kawamura, Masanobu Shimada

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

An L-band geophysical model function is developed using Japanese Earth Resources Satellite-1 (JERS-1) synthetic aperture radar (SAR) data. First, we estimate the SAR system noise, which has been a serious problem peculiar to the JERS-1 SAR. It is found that the system noise has a feature common in all the SAR images and that the azimuth-averaged profile of noise can be expressed as a parabolic function of range. By subtracting the estimated noise from the SAR images, we can extract the relatively calibrated ocean signals. Second, using the noise-removed SAR data and wind vector data from the NASA Scatterometer and buoys operated by the Japan Meteorological Agency, we generate a match-up dataset, which consists of the SAR sigma-0, the incidence angle, the surface wind speed, and wind direction. Third, we investigate the sigma-0 dependence on incidence angle, wind speed, and wind direction. While the incidence angle dependence is negligible in the present results, we can derive distinct sigma-0 dependence on wind speed and direction. For wind speeds below 8 m/s, the wind direction dependence is not significant. However, for higher wind speeds, the upwind-downwind asymmetry becomes very large. Finally, taking into account these characteristics, a new L-band-HH geophysical model function is produced for the SAR wind retrieval using a third-order harmonics formula. Resultant estimates of SAR-derived wind speed have an rms error of 2.09 m/s with a negligible bias against the truth wind speed. This result enables us to convert JERS-1 SAR images into the reliable wind-speed maps.

Original languageEnglish
Pages (from-to)518-531
Number of pages14
JournalIEEE Transactions on Geoscience and Remote Sensing
Volume41
Issue number3
DOIs
Publication statusPublished - 2003 Mar 1

Keywords

  • Japanese Earth Resources Satellite-1 synthetic aperture radar (JERS-1 SAR)
  • L-band model function
  • Synthetic aperture radar (SAR) wind retrieval

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Earth and Planetary Sciences(all)

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