Satellite Oceanography
Physical Oceanography

Ocean circulation is neither smooth nor steady but instead fluctuates vigorously on many space and time scales, similar to weather in the atmosphere. Observing this ocean variability from ships or buoys would be difficult and costly. Satellites are one of the very few means to sample the ocean frequently and on a global scale, but satellite measurements are limited to surface conditions. The goal of satellite oceanography is therefore to obtain measurements of the surface temperature, color, surface height and currents, as well as the wind stress that drives the ocean circulation. We use these measurements to study the ocean general circulation, its large-scale, low frequency variability, biological productivity, turbulent eddy energy, and air-sea interactions.

Satellite oceanography is one of the rapidly growing fields in modern oceanography, and it has an expanding role in all areas of ocean and climate research. New sensors are under development to measure salinity and velocity, and new analysis techniques are being developed to better interpret existing measurements. Researchers from Physical Oceanography and other SIO curricula are involved in most of those new developments.

In physical oceanography at Scripps, we use remote sensing in various ways. In recent years, altimetry (which measures sea surface height) and scatterometry (which measures wind speed and direction) have been particularly important. Figure 1 depicts the TOPEX/POSEIDON altimeter flying over the Pacific Ocean parallel to the coast of California, measuring the height and the shape of the sea surface.

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Figure 1: The TOPEX/POSEIDON satellite trans-passing the North Pacific in south-east directions
at an altitude of 1300km

TOPEX/POSEIDON data have been analyzed on a global scale to characterize the statistics of ocean variability and the regional variations between different parts of the ocean. The outcome of those studies is important for the dynamical interpretation of ocean observations and for the improvement of present ocean general circulation models.

Figure 2 shows an example of sea surface variability estimates obtained from the satellite altimeter. Ocean circulation is highly variable, especially near major current systems, such as the Gulf Stream. Variability is associated with eddies, phenomena similar to weather patterns in the atmosphere. Satellites see these eddies because they influence sea surface height and sea surface temperature.

Remote sensing research in physical oceanography at SIO offers exciting opportunities for new graduate students to become involved in an increasingly important field. Active research involves sea surface temperature, sea surface height, surface wind stress, and air-sea interaction.
 

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Figure 2:Root mean squared sea surface height variability observed locally by TOPEX/POSEIDON during the 5 year period 
December 1992 to December 1997  and averaged in 2 by 2 degrees geographical areas. Note  the large variability
associated with strong ocean currents that are involved in mixing and transporting heat poleward, where it is then
released to the atmosphere.

Researchers

Scripps faculty active in satellite remote sensing research and education:

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Physical Oceanography at Scripps