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Ocean Surface Topography from Space
NEWSROOM
Dynamic Topography of Earth's Oceans
June 01, 1993

3-D Dynamic Topography

Ocean Topography is a measure of sea level relative to Earth's geoid, a surface on which the gravity field is
uniform. Oceanographers use ocean topography maps to
calculate the speed and direction of ocean currents in the
same way meteorologists use maps of atmospheric pressure to
calculate the speed and direction of winds. TOPEX/Poseidon
is the first space mission that allows scientists to map
ocean topography with sufficient accuracy to study the
large-scale current systems of the world's oceans.

The total relief of ocean topography shown in this image is about 2 meters. The color scale corresponds to the grades
of the relief in centimeters. The vertical scale is greatly
exaggerated to illustrate the three-dimensional perspective
of the topography. In this image, the maximum sea level
(shown in white) is located in the western Pacific Ocean and
the minimum sea level (indicated by magenta and dark blue)
is shown around Antarctica. In the northern hemisphere,
ocean currents flow clockwise around the highs of ocean
topography and counterclockwise around the lows; this
process is reversed in the southern hemisphere. These highs
and lows are the oceanic counterparts of atmospheric
circulation systems. While the basic structure of these
ocean systems is constant, the details of the systems are
constantly changing.

Although this image was constructed from only 10 days of TOPEX/Poseidon data (October 3 to October 12, 1992), it
reveals most of the current systems that have been
identified by shipboard observations collected over the last
100 years. For instance, major current systems such as
Kuroshio (the current south of Japan), the Gulf Stream and
the Antarctic Circumpolar Current, among others, are clearly
visible.

The ocean topography data used in this image were calculated by scientists at the National Aeronautics and
Space Administration (NASA) Goddard Space Flight Center. The
image was produced by the Jet Propulsion Laboratory (JPL)
Oceanography Group.

NASA/JPL/Caltech

JPL Identification #: P-42106
Source: Jet Propulsion Laboratory

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