Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.

(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)

Analysis of dual-polarization microwave ocean images obtained with a high-resolution X-band radar

Yong Liu, University of Massachusetts Amherst


Dual-polarized X-band ocean images were obtained using a high-resolution phased-array radar at 3$\sp\circ$ grazing angle. For vertical polarization, the backscatter can be explained using resonant scattering and Composite Surface Theory. For horizontal polarization, the backscatter is dominated by discrete strong scattering events with high Doppler, or sea-spikes. Sea-spike properties are presented and compared with several low-grazing-angle ocean scattering models. Comparison of larger sea-spikes with surface wave features indicates that approximately 30% of observed sea-spikes are associated with actively breaking waves (whitecaps), while the remainder are identified with steep wave features which may or may not break. Using the imaging nature of the radar, statistics of sea-spike spatial and temporal properties are derived and compared with surface wind and wave parameters. Sea-spikes tend to travel in the direction of the wind at a speed considerably slower than the phase speed of the dominant waves, but are consistent with a breaking wave scale based on the downward acceleration spectrum. Surface coverage of sea-spikes has a power-law dependence on friction velocity with an exponent of 2.3, while sea-spike event density does not show a converging dependence on wind speed or friction velocity.

Subject Area

Electrical engineering

Recommended Citation

Liu, Yong, "Analysis of dual-polarization microwave ocean images obtained with a high-resolution X-band radar" (1997). Doctoral Dissertations Available from Proquest. AAI9809359.