Record Details

Side looking airborne radar mapping of wave refraction patterns at the mouth of the Columbia River

ScholarsArchive at Oregon State University

Field Value
Title Side looking airborne radar mapping of wave refraction patterns at the mouth of the Columbia River
Names Bell, James W. (creator)
Rosenfeld, Charles L. (advisor)
Date Issued 1979-04-30 (iso8601)
Note Graduation date: 1979
Abstract The ocean wave conditions at the mouth of the Columbia River have
long proven a hazard to ship navigation. Over 62 major shipwrecks
have occurred at, or in the vicinity of the river entrance. The wave
pattern is extremely complex, varying seasonally with prevailing winds
and river discharge, as well as the tidal cycle. Analysis of the cornplex
wave refraction process requires repetitive wave crest mapping at
critical periods such as peak ebb current, winter storms, and spring
ti des.
Oregon Army National Guard Mohawk aircraft equipped with the
AN/APQ-94 Side Looking Airborne Radar system have overcome most of the
monitoring limitations, providing scheduling flexibility, cloud penetration,
and a constant angle of illumination, although the scanning
nature of the system requires a correction for the progression of the
wave crest between scans. This correction was accomplished by adding
the resultant vectors of apparent wave refraction patterns obtained
from a given flight to those of a subsequent flight flown imediately
after, at a reciprocal azimuth.
SLAR imagery interpretation and analysis was aided by color
density slicing, which enables differences in wave steepness and
height to be detected. Wave crest patterns from the imagery were traced on an equivalent scale as previous wave pattern predictions,
enabling easy comparison. The use of photographic enlargements of the
SLAR imagery was used in conjunction with weather and sea data, in
aiding further exploitation of the imagery to aid the understanding
of wave action when storm produced swell encounters strong ebb current
velocities seaward of the river entrance.
Analysis of the SLAR imagery of the river entrance has Increased
the understanding of swell-ebb current interaction by detecting the
locations and intensities of interaction and its products, the steepened/
heightened swell over the navigation channel. The imagery may well
help in increasing the safety of the mouth of the Columbia River for
ship navigation.
Genre Thesis
Topic Ocean waves -- Columbia River Estuary (Or. and Wash.)
Identifier http://hdl.handle.net/1957/9655

© Western Waters Digital Library - GWLA member projects - Designed by the J. Willard Marriott Library - Hosted by Oregon State University Libraries and Press