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Proceedings Paper

Airborne lidar sensing of internal waves in a shallow fjord
Author(s): James H. Churnside; Richard Marchbanks; Jennifer H. Lee; Joseph A. Shaw; Alan Weidemann; Percy Donaghay
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Paper Abstract

A dual polarization lidar was used to sense internal waves from a small aircraft. Internal waves are gravity waves that are formed by a vertical displacement of a density gradient in the ocean. If the perturbation is great enough, a nonlinear wave is produced and the balance between nonlinearity and dispersion can create a soliton-like wave packet. We observed nonlinear wave packets in West Sound, Orcas Island, Washington. In this region, a density gradient is formed in the summer by solar heating of the surface water. The perturbation is produced by strong tidal flow through a narrow, shallow channel at the mouth of the sound. Plankton layers form in association with the density gradients, and these layers produce an enhanced lidar return that moves up and down with the wave. We observed these internal waves with a lidar operating at 532 nm. They were much more visible when the receiver was polarized orthogonal to the transmitted laser pulse. This was the case whether linear or circular polarization was used, with no significant difference between the two cases. These internal waves were also visible to the naked eye, when the surface currents produced by the waves modulated the small surface waves that produce the apparent texture of the ocean surface.

Paper Details

Date Published: 12 June 2012
PDF: 6 pages
Proc. SPIE 8372, Ocean Sensing and Monitoring IV, 83720P (12 June 2012); doi: 10.1117/12.918099
Show Author Affiliations
James H. Churnside, NOAA Earth System Research Lab. (United States)
Richard Marchbanks, Univ. of Colorado (United States)
NOAA Earth System Research Lab. (United States)
Jennifer H. Lee, NOAA Earth System Research Lab. (United States)
Joseph A. Shaw, Montana State Univ. (United States)
Alan Weidemann, U.S. Naval Research Lab. (United States)
Stennis Space Ctr. (United States)
Percy Donaghay, The Univ. of Rhode Island (United States)


Published in SPIE Proceedings Vol. 8372:
Ocean Sensing and Monitoring IV
Weilin Will Hou; Robert Arnone, Editor(s)

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