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W133
Atlas Pgs. 11-12 & 23-24

Central Equatorial Pacific Ocean
Fronts, chaotic wave lines (suloys), internal waves, and current shear

Significance: The U.S. oceanographic community is presently involved in a large, multi-national research effort to understand global biochemical cycles; JGOFS (Joint Global Ocean Flux Study). The focus of this research effort will soon turn from the North Atlantic Ocean to the Equatorial Pacific Ocean. The Equatorial Pacific is believed to play an important role in the annual global uptake of atmospheric CO2 by the oceans. In addition to the JGOFS work, other researchers are interested in the Equatorial Pacific Ocean as a short-term predictor of El Nino. Space Shuttle photography of surface dynamical features, seen in the sunglint pattern, will aid scientists in understanding the ocean physical processes at the equator and the role they play in short-term and long-term climate change.

Physical Characteristics: Current flow in the Equatorial Pacific is generally from east to west and is driven by the nearly constant easterly winds. As the current travels westward across the Pacific, differences in Coriolis force causes the current to diverge north and south of the equator, resulting in the upwelling of cooler, nutrient-rich water. The combination of high nutrient concentration and high daily average solar radiation at the equator enables phytoplankton to grow rapidly. Consequently, the annual primary productivity of the Equatorial Pacific is quite high.

An interesting characteristic of the Equatorial Pacific Ocean, as depicted in Space Shuttle photography, is the presence of long shear lines or suloys (areas of chaotic waves), generally in a north-south orientation. These shear lines are believed to be the boundary between two different water masses, perhaps differing in temperature and perhaps related to the nearly constant upwelling of cold water that takes place at the equator. These features can only be seen in the sunglint pattern and often only after the photography has been developed and analyzed. 

Observation Techniques: Linhof photography of the sunglint pattern using color visible film and a 250 mm lens. While you should be able to see some of the stronger fronts in the sunglint, do not look for the features before taking the picture as they tend to be quite subtle and pass through the sunglint pattern quickly. Thus, you risk missing the feature all together. Simply photograph the Equatorial Pacific sunglint pattern (within 10° of the equator) when you see it.

Alternate Sites: Equatorial Atlantic Ocean (0-10°N, 25-40°W)

Center point: 5°N, 140°W

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