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Towards Mapping the Ocean Surface Topography at 1 km Resolution

Lee-Lueng Fu(1) and Ernesto Rodriguez(1)

(1) Jet Propulsion Laboratory/Caltech, 4800 Oak Grove Drive, Pasadena, CA 91109, United States

Abstract

Since Seasat we have realized the wealth of information in the details of the map of the surface topography of the ocean. The world was stunned by the first maps of the ocean current variability and the marine gravity anomalies. Despite the revolutionary impact of radar altimetry achieved over the past quarter century, its sampling capability has always been a compromise between the spatial and temporal requirements. As a result, high spatial resolution can only be achieved in the along-track direction, leading to asymmetry in the radar's mapping capability. For example, the zonal currents of the ocean tend to be better determined than the meridional currents, and the meridional gravity anomalies tend to be better determined than the zonal anomalies.

A new technology has been demonstrated by the Shuttle Radar Topography Mission for mapping the earth's land topography using the technique of radar interferometry. We propose to use the same technique with synthetic aperture radar to achieve spatially uniform high resolution for mapping the ocean surface topography. The intrinsic resolution is in the range of tens of meters. After spatial averaging, we can achieve centimetric precision at 1 km resolution, which is less than the smallest eddy scales in the ocean by an order of magnitude. For the first time, ocean eddies which account for 90 % of the kinetic energy of the ocean can be fully resolved from space. This new measurement will enable the calculation of ocean surface currents and marine gravity anomalies with much improved accuracies. It can also be applied to mapping the elevation of water surface on land as well as the free board of sea ice and elevation of land ice. The measurement principle and anticipated benefits as well as some of the design issues such as the selection of orbit parameters and radar frequency will be discussed.

 

Workshop presentation

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                 Last modified: 07.10.03