Accession Number:

ADA230799

Title:

An Automated Technique for Locating the Gulf Stream in Altimeter Profiles

Descriptive Note:

Corporate Author:

NAVAL OCEANOGRAPHIC AND ATMOSPHERIC RESEARCH LAB STENNIS SPACE CENTER MS

Personal Author(s):

Report Date:

1990-01-01

Pagination or Media Count:

2.0

Abstract:

The Navys GEOSAT radar altimeter measures range from the satellite to the sea surface. Mesoscale ocean features such as the Gulf Stream and its associated eddies exhibit as much as 1.5 meters of vertical relief relative to the marine geoid. Since this relief is sufficient to be detected by the altimeter, the altimeter is a valuable adjunct to IR imagery for analysis of mesoscale oceanic structure. Despite the large altimetric signal associated with the Gulf Stream, its detection is not a trivial problem. The greatest hindrance to detection is the fact that the geoid, which is subtracted from the sea surface height to give the oceanographic residuals, is itself derived from altimeter data. Thus, the geoid contains contributions from the oceanography at locations where major oceanographic features are geographically stationary. The Gulf Stream, toward its western end, fits this condition and, thus, its mean topographic expression is present as an error in the marine geoid. With the feature of interest contained in the geoid, subtraction of the geoid to produce oceanographic residuals can alter the magnitude or appearance of the feature, including complete cancellation of the feature if its present realization happens to resemble its mean topographic signal. We approximated the marine geoid along two tracks from the GEOSAT ERM with a polynomial whose order is chosen to prohibit inclusion of the mesoscale features. The Gulf Stream appears much more prominently when the polynomial is used as the reference surface rather than the altimetric geoid. The 2nd phase of the paper deals with use of the linear Hough transform to automatically detect and locate the Gulf Stream signal in the polynomial residuals.

Subject Categories:

  • Physical and Dynamic Oceanography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE