Comparison of derived wind speed from synthetic aperture radar and scatterometer during the ERS tandem phase

A validation of wind retrieval from synthetic aperture radar (SAR) images has been performed by comparing wind speed estimated from European Remote Sensing Satellite (ERS)-2 SAR with ERS-1 wind scatterometer (WSC) measurements, both using the CMOD-IFR2 algorithm. This was made possible by using data from the open ocean and north of 63/spl deg/ of latitude during the tandem phase of the ERS satellites. Here, the WSC and SAR coverage overlapped with a time difference in the data acquisition of only 30 min. The SAR-derived wind speed values from subimages centred around the WSC wind vectors, agreed to within /spl plusmn/2 m/s but underestimated the WSC wind speed values by approximately 0.4 m/s. Studying the spatial variability of the high resolution wind speed values leads the authors to conclude that the SAR wind field seems useful at least down to a spatial resolution of 500 m, provided that external information on the wind direction is available.

[1]  W. Linwood Jones,et al.  Radar backscatter from the ocean: Dependence on surface friction velocity , 1978 .

[2]  Werner Alpers,et al.  Katabatic wind fields in coastal areas studied by ERS-1 synthetic aperture radar imagery and numerical modeling , 1998 .

[3]  Paris W. Vachon,et al.  ERS-1 SAR images of atmospheric gravity waves , 1995, IEEE Trans. Geosci. Remote. Sens..

[4]  K. Katsaros,et al.  Observation of tropical cyclones by high-resolution scatterometry , 1998 .

[5]  Ola M. Johannessen,et al.  Coastal wind field retrievals from ERS synthetic aperture radar images , 1998 .

[6]  E. Attema,et al.  The Active Microwave Instrument on-board the ERS-1 satellite , 1991, Proc. IEEE.

[7]  Chung-Ru Ho,et al.  Coastal lee waves on ERS-1 SAR images , 1998 .

[8]  I. Robinson,et al.  Demonstration of an improved calibration scheme for ERS-l SAR imagery using a scatterometer wind model , 1996 .

[9]  David L. T. Anderson,et al.  Scatterometer data interpretation: Estimation and validation of the transfer function CMOD4 , 1997 .

[10]  W. Alpers,et al.  Atmospheric boundary layer rolls observed by the synthetic aperture radar aboard the ERS-1 satellite , 1994 .

[11]  D. Offiler.  The Calibration of ERS-1 Satellite Scatterometer Winds , 1994 .

[12]  Ola M. Johannessen,et al.  Synthetic aperture radar imaging of upper ocean circulation features and wind fronts , 1991 .

[13]  P. W. Vachon,et al.  Validation of wind vector retrieval from ERS-1 SAR images over the ocean , 1996 .

[14]  Naoto Ebuchi,et al.  Directivity of wind vectors derived from the ERS‐1/AMI scatterometer , 1998 .

[15]  Paris W. Vachon,et al.  An ERS 1 synthetic aperture radar image of atmospheric lee waves , 1994 .

[16]  P. Vachon,et al.  Analysis of ERS-1/2 synthetic aperture radar wave mode imagettes , 1998 .