Satellite Remote Sensing

(a) SEASAT operated between June and November 1978.
(b) GEOSAT monitored the oceans between 1985 and 1990.
(c) TOPEX-POSEIDON is a joint program of NASA and the French space agency CNES. It began a three year ocean observation program in 1993.
(d) ERS-2, a European satellite, carries radar and microwave systems to take measurements through clouds and darkness.
(e) SEASTAR carries a sensor to study the distribution of ocean plant life.

With satellites, oceanographers can study the oceans as a global system. NASA's NIMBUS-7 satellite, launched in 1978, monitored back radiation and reflection from the earth's surface and carried a sensor package called the Coastal Zone Color Scanner that detected multi-band radiant energy reflecting from Chlorophyll a in sea and land plants. Data from NIMBUS-7 were used to make the images of the world's production of marine plant life. SEASAT (a) was a specialized oceanographic satellite that was launched in June of 1978. It was capable of measuring the distance between the satellite and the sea surface with accuracy of about 5 cm over a narrow observational width. Radar echoes returning to multiple receiving antennas on the satellite measured the scattering patterns caused by surface waves. Theses patterns gave information on wave height related to wind speed and scattering direction related to wind direction. The altimeter detected elevation changes in the sea surface that were used to measure tides, currents, sea-floor topography, and changes in sea level. GEOSAT (b) was launched in 1985 to replace SEASAT. It monitored sea-level topography, surface winds and waves, local gravity changes, and abrupt boundaries between water types. The SEASTAR launched in 1996, carrying a system called SeaWiFS (Sea Wide Field). SeaWiFS returns the ability to study the distribution of chlorophyll and plant life in the oceans. NASA's Earth Observing System (EOS) series of satellites, and the Total Ozone Mapping Spectrometer (TOMS) was launched on July 2, 1996. These satellites will complement on-going programs by monitoring the roles of clouds, radiation, water vapor, and precipitation in our weather systems; the gas exchange between the oceans and the atmosphere; and the role of polar ice.