For the first time in history, NASA is releasing dramatic images documenting the Earth's changing biology, both on land and in the oceans, as observed from space for one continuous year.
The changing seasons of life, the "pulse of the planet," are being monitored by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), which was launched on Aug. 1, 1997, and has continuously produced data since Sept. 18, 1997. The SeaWiFS mission is the first NASA Earth Science data purchase in which industry led the development of the full mission.
"Although originally designed to observe the oceans, SeaWiFS provides a unique capability to study the land and atmospheric processes as well," said Dr. Gene Feldman, oceanographer, who heads SeaWiFS' data processing team at NASA's Goddard Space Flight Center, Greenbelt, MD. "As a result, we can monitor changes in the global biosphere with a single sensor over land and ocean."
Among the highlights of SeaWiFS' first continuous year of observation were new insights into the impact of the El NiŠo climate anomaly on ocean life. Further, SeaWiFS was able to monitor a variety of natural disasters, including fires in Florida, Mexico, Canada, Indonesia and Russia; floods in China; dust storms in the Sahara and Gobi Deserts; and the progress of hurricanes, such as Bonnie and Danielle.
SeaWiFS enabled scientists to witness the ocean transition from El NiŠo to La NiŠa conditions in the Equatorial Pacific, specifically around the Galapagos Island. The instrument also allowed researchers to observe the striking speed with which the ocean returned to its pre-El NiŠo state. While El NiŠo essentially shut down the highly productive Equatorial Pacific ecosystem, the subsequent La NiŠa resulted in unprecedented phytoplankton blooms, which stretched across the entire basin from the South American coast to the Western Pacific warm pool.
Phytoplankton are microscopic marine plants that remove carbon dioxide from the atmosphere for internal use. Scientists are eager to understand this exchange of carbon dioxide and the role it plays in the global climate.
"One of the most fascinating events witnessed in the global ocean was the Spring bloom in the North Atlantic," said Dr. Charles McClain, SeaWiFS project scientist. "While many regions of the ocean experience a spring bloom, the event in the North Atlantic was the most dramatic."
During the winter, storms and surface cooling mix the surface waters of the Atlantic, replenishing the nutrient supply from the deep, cold, nutrient-rich waters. Once sunlight is sufficient to support plant growth, phytoplankton populations explode and persist for nearly three months until nutrients are depleted. This bloom migrates northward following the Sun throughout the spring and summer.
Unexpected phenomena observed by SeaWiFS, according to McClain, were the massive blooms of coccolithophores, a unique type of phytoplankton in the Bering Sea. These blooms may have a significant impact on fish populations in this area, one of the most productive fishery regions in the global ocean.
During the summer-fall of 1997 and spring of 1998, expansive blooms of coccolithophores occurred along the Alaskan shelf. These were the first observations of blooms of this magnitude in the Bering Sea. Coccolithophores shed vast numbers of white carbonate platelets which cloud the water. "The net result was fish that normally spawn in the adjacent rivers could not trasverse the bloom in order to enter the rivers to spawn. In addition, local bird and marine mammal populations had a high mortality rates due to starvation because the fish migrated to other waters," said McClain.
NASA is leading an international collaboration using SeaWiFS data. More than 800 scientists representing 35 countries already have registered to use the data. There are over 50 ground- stations throughout the world which receive data from the spacecraft. In addition, the unique government-industry partnership with ORBIMAGE, Dulles VA, represents a new way of doing business for NASA.
SeaWiFS is an essential component of NASA's Earth Sciences enterprise, an ongoing effort to study the changing global environment. Using the unique perspective available from space, NASA will observe, monitor and assess large-scale environmental processes focusing on climate change.
Remarkable images from this mission are available on the World Wide Web at URL: http://seawifs.gsfc.nasa.gov/SEAWIFS.html
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