Publication Date

2019-11-27

Availability

Embargoed

Embargo Period

2021-11-26

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Applied Marine Physics (Marine)

Date of Defense

2019-07-03

First Committee Member

Roland Romeiser

Second Committee Member

Hans Graber

Third Committee Member

Bjoern Lund

Fourth Committee Member

Brian Haus

Fifth Committee Member

Jochen Horstmann

Abstract

During three research cruises in the Pacific, a vertically-polarized X-band Doppler Marine Radar (DMR) was installed onboard the research vessels. One of the goals during these cruises was to measure near-surface currents. Ocean currents have been measured with marine radar since the 1980’s using the dispersion shell technique. However, currents measured in this classical way cannot resolve fine-scale current variations. To fill this gap, the Doppler Velocity Synthesis algorithm (DoVeS) is developed to synthesize radial Doppler velocity information from a moving ship in order to obtain a two-dimensional surface current vector field around the ship track. During the first cruise, our primary goal was to determine the near-surface response to underwater bathymetry changes. Thousands of DMR intensity images are analyzed and three types of ocean surface features are identified near bathymetry changes: internal waves, convergent fronts, and surface slicks, which sometimes aid in the surface feature imaging process. These ocean surface features are examined with respect to their association with the surrounding bathymetry. Finally, to showcase the fine-scale capabilities of the DoVeS method, the Doppler velocity convergence and divergence above internal waves off the coast of California is compared with echosounder data, which show the shape of the internal wave beneath the ship. The alternating Doppler zones are phase shifted with respect to the internal wave. Different radar signatures correspond to different stages of the internal wave's shoaling process. The internal wave shoaling process, shape of the pycnocline, radar signature, wave velocity, and wave reflection are analyzed and discussed.

Keywords

marine radar; Doppler; bathymetry; internal waves; Palau; inner shelf

Available for download on Friday, November 26, 2021

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