X-BAND LOW-GRAZING-ANGLE OCEAN BACKSCATTER OBTAINED DURING LOGAN 1993

This paper reviews X-band ocean microwave backscatter data from the LO GAN (LOw Grazing ANgle) experiment conducted on the Chesapeake Light T ower by the Naval Air Warfare Center, The data were collected under va ried wind, sea, and swell conditions that provide some new insights in to low-grazing-angle backscatter phenomena, Transient backscatter peak s called ''sea spikes'' have long been associated with deep-water brea king waves; however, they have yet to be fully reconciled with backsca tter and hydrodynamic theories, New analysis techniques have been appl ied to the LOGAN data that take advantage of the unique characteristic s of sea spikes and their dynamics, High-resolution Doppler spectra ar e organized relative to the space-time centroids of the sea-spike clus ters and conditionally averaged by RCS strength, The mean Doppler vari ation of the strongest sea spikes then map the breaking-wave structure just as Doppler histories measured at moderate grazing angles map the dynamics of the dominant linear surface-wave components, While breaki ng waves are manifest to some degree in backscatter data at all grazin g angles, a non-Bragg-scatter mechanism accentuates the crest scatteri ng at low grazing angles, The phenomena potentially can be exploited f or remote ocean sensing and imaging.