Background of the SeaWiFS Project


seastar image The purpose of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project is to provide quantitative data on global ocean bio-optical properties to the Earth science community. Subtle changes in ocean color signify various types and quantities of marine phytoplankton (microscopic marine plants), the knowledge of which has both scientific and practical applications. The SeaWiFS Project will develop and operate a research data system that will process, calibrate, validate, archive and distribute data received from an Earth-orbiting ocean color sensor. A detailed description of the objectives, organization and operations as well as the current status of the SeaWiFS Project is available.

The SeaWiFS Mission is a part of NASA's Earth Science Enterprise, which is designed to look at our planet from space to better understand it as a system in both behavior and evolution.

diatom imageThe concentration of microscopic marine plants, called phytoplankton, can be derived from satellite observation and quantification of ocean color. This is due to the fact that the color in most of the world's oceans in the visible light region, (wavelengths of 400-700 nm) varies with the concentration of chlorophyll and other plant pigments present in the water, i.e., the more phytoplankton present, the greater the concentration of plant pigments and the greener the water.

Ocean color data have been deemed critical by the oceanographic community for the study of ocean primary production and global biogeochemistry. "Primary production" refers to the organic material in the sea that is produced by "primary producers." These "primary producers," i.e. algae and some bacteria, exist at the lowest levels of the food chain and use sunlight or chemical energy, rather than other organic material, as sources of energy. It is thought that marine plants remove carbon from the atmosphere at a rate equivalent to terrestrial plants, but knowledge of interannual variability is very poor.

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Since an orbiting sensor can view every square kilometer of cloud-free ocean every 48 hours, satellite-acquired ocean color data constitute a valuable tool for determining the abundance of ocean biota on a global scale and can be used to assess the ocean's role in the global carbon cycle and the exchange of other critical elements and gases between the atmosphere and the ocean. SeaWiFS will operate as a follow-on sensor to the Coastal Zone Color Scanner (CZCS), which ceased operations in 1986. In the first arrangement of its kind, the Government will procure space-based environmental remote sensing data for research purposes from a commercial operator. Orbital Sciences Corporation (OSC) will integrate SeaWiFS into its SeaStar spacecraft and will market the data for commercial and operational use following launch.

The following icons provide links to short mpeg animations showing (1) the SeaStar Spacecraft, (2) simulated daily SeaWiFS coverage, (3) the lunar calibration procedure and (4) and actual Pegasus launch.

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To learn more about the SeaWIFS Project, take a look at the

SeaWiFS Project Information Page

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SeaWiFS Project Home Page

gene carl feldman (301) 286-9428