November 03, 2003
This equatorial quiet contrasts with the Bering Sea, Gulf of Alaska and U.S. West Coast where lower-than-normal sea surface levels and cool ocean temperatures continue (indicated by blue and purple areas).
The image above is a global map of sea surface height, accurate to within 30 millimeters. The image represents data collected and composited over a 10-day period, ending on Nov. 3, 2003. The height of the water relates to the temperature of the water. As the ocean warms, its level rises; and as it cools, its level falls. Yellow and red areas indicate where the waters are relatively warmer and have expanded above sea level, green indicates near normal sea level, and blue and purple areas show where the waters are relatively colder and the surface is lower than sea level. The blue areas are between 5 and 13 centimeters (2 and 5 inches) below normal, whereas the purple areas range from 14 to 18 centimeters (6 to 7 inches) below normal.
The Jason satellite carries a dual-frequency radar altimeter. This instrument
beam microwave pulses-at 13.6 and 5.3 Gigahertz, respectively-downward
toward the Earth. To determine the ocean's height, the instrument precisely
measures the time it takes for the microwave pulses to bounce off the
surface and return to the spacecraft. This measure, multiplied by the speed
of light, gives the range from the satellite to the ocean surface. (For more
details, visit the Jason Website.)
A Mostly Quiet Pacific