Wave Measurements Using a Dual-Beam Interferometer Near Gulf Stream Boundary
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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A dual-beam interferometric synthetic aperture radar provides two velocity components of the ocean current remotely from a single fight pass. Combining two flight passes, all three orthogonal components of the surface velocity can be retrieved. An experiment was conducted near the Gulf Stream GS boundary. A sharp change of the surface velocity of about 1 ms over a 500 m distance was measured. The wave condition is dominated by a 14-s swell system and low wind velocity. The wave variance inside GS is about twice the wave variance outside the GS in the present data. The large difference in the wave variance is considerably higher than that can be expected from hydrodynamic modulation. An ocean current system with strong current shears such as the Gulf Stream is a wave guide and can trap waves with the right combination of wavelengths and propagation directions. Numerical calculations indicate that the wave properties of the data set may satisfy the conditions for wave trapping by the Gulf Stream.
- Physical and Dynamic Oceanography