Real-time observations of Southern Ocean wave fields from the Shuttle Imaging Radar

During the April and October 1994 flights of the space shuttle Endeavour, C-band synthetic-aperture radar (SAR) signal was acquired and processed in real-time into ocean wave images and two-dimensional image spectra by an on-board processor. The image spectra were transmitted to the ground as they were acquired. During 20 days of observations, spanning the two missions, over 100000 spectra were collected. These data provide the first truly synoptic directional measurements of the Southern Ocean wave field. With additional processing, estimates of ocean wavelength and propagation direction were extracted from the spectra. During the October mission, daily comparisons of these estimates with wave model predictions were made available at a World Wide Web site. The authors describe the computations performed by the processor and the real-time data flow and ground processing. In addition, they summarize and interpret some gross characteristics of the processor-observed real-time wave field from the April and October missions