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Ocean Surface Topography from Space
NEWSROOM
Wind Speeds over Earth's Oceans & Wave Heights in Earth's Oceans
June 01, 1993

T/P Wind & Waves

The image shows the global distribution of wind speed as observed by TOPEX/Poseidon's dual-frequency radar
altimeter from October 3 to October 12, 1992. Wind speed is
determined by the strength of the return radar pulses. A
calm sea serves as a good reflector and returns a strong
pulse; on the other hand, a rough sea tends to scatter the
radar signal and returns a weak pulse. In this image, the
strongest winds (over 15 meters per second or 54 kilometers
per hour) are found in the Southern Ocean and are indicated
by white. The highest waves are also located in this region;
see the wave height image. In general, there is a high
degree of correlation between wind speed and wave height.
The weakest winds (represented by magenta and dark blue) are
found in the western tropical Pacific Ocean, the tropical
Atlantic Ocean and the tropical Indian Ocean. A few bands of
these so-called trade winds are also noticeable in the
subtropical regions.

At bottom, global wave height data acquired by TOPEX/Poseidon's dual-frequency radar altimeter from October
3 to October 12, 1992, were used to create this image. Wave
height is determined by the shape of the return radar pulse.
A calm sea with low waves returns a condensed pulse whereas
a rough sea with high waves returns a stretched pulse. In
this image, the highest waves occur in the Southern Ocean,
where waves over 6 meters in height (represented by white)
are found. The strongest winds are also found in this
region; see the wind speed image. The lowest waves
(indicated by dark blue) are found primarily in the tropical
and subtropical oceans where the wind speed is also the
lowest. In general, there is a high degree of correlation
between wind speed and wave height. Simultaneous
observations of wind speed and wave height by TOPEX/Poseidon
will help improve our ability to forecast ocean waves.

NASA/JPL/Caltech

JPL Identification #: P-41498 (Wind Speeds), P-41497 (Wave Heights)
Source: Jet Propulsion Laboratory

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