Scientists using NASA and other satellite data discovered an unusual long-lasting, whirlpool-like ocean eddy that generated a dramatic increase in the marine food supply off the Hawaiian coast in 1999.
The eddy, named Loretta, began spinning up in the Alenuihaha Channel between the islands of Hawaii and Maui during mid-May 1999 and maintained a presence in the lee of the Hawaiian Islands until January 2000. Over the 8-month period, the eddys churning motion brought up a great amount of nutrients from the ocean depths, enhancing the plankton population on the oceans surface, and providing a banquet for marine life.
Several organizations collaborated to track Loretta, and other Hawaiian eddies and their ecological benefits. The University of Hawaii, NASA and the National Oceanic and Atmospheric Administrations (NOAA) National Marine Fisheries Service (NMFS) integrated information from two independent satellite sensors that measure sea surface temperature (SST) and ocean color. NASAs Sea-viewing Wide Field-of-View Sensor (SeaWiFS) satellite tracked ocean chlorophyll, and NOAAs Geostationary Operational Environmental Satellite-10 (GOES) satellite tracked sea surface temperatures. Data from shipboard measurements taken aboard the NOAA ship Townsend Cromwell were also used to track Loretta.
Eddies naturally occur in this locale for periods of several weeks to a few months, but Loretta persisted for 8 months according to satellite data, said Bob Bidigare of the University of Hawaii. After January 2000, Loretta started to move slowly westward, and eventually weakened beyond detection, but not before bringing a tremendous amount of deep-sea nutrients to the surface of the ocean.
Eddies are usually 30-125 miles (50-200 km)in diameter, and resemble hurricanes in the water. Like hurricanes, each eddy is given a name to keep better track of it. In 1999, researchers named the eddy Loretta. Around the Hawaiian Islands, eddies are caused when northeasterly trad
Contact: Cynthia M. OCarroll
NASA/Goddard Space Flight Center