The Coastal Zone Color Scanner Experiment

The Coastal Zone Color Scanner Experiment (CZCS) was the first instrument devoted to the measurement of ocean color and flown on a spacecraft. Although other instruments flown on other spacecraft had sensed ocean color, their spectral bands, spatial resolution and dynamic range were optimized for land or meteorological use and had limited sensitivity in this area, whereas in CZCS, every parameter was optimized for use over water to the exclusion of any other type of sensing. CZCS had six spectral bands, four of which were used primarily for ocean color. These were of a 20 nanometer bandwidth centered at 443, 520, 550, and 670 nm. Band 5 had a 100 nm bandwidth centered at 750 nm and a dynamic range more suited to land. Band 6 operated in the 10.5 to 12.5 micrometer region and sensed emitted thermal radiance for derivation of equivalent black body temperature. (This thermal band failed within the first year of the mission, and so was not used in the global processing effort.) Bands 1-4 were preset to view water only and saturated when the IFOV was over most types of land surfaces, or clouds.

The most important objective of the Coastal Zone Color Scanner mission was to determine if satellite remote sensing of color could be used to identify and quantify material suspended or dissolved in ocean waters. Specifically CZCS attempted to discriminate between organic and inorganic materials in the water, determine the quantity of material and discriminate between different organic particulate types.

Being satellite mounted, CZCS was able to provide measurements of ocean color over large geographic areas in short periods of time in a way that was not previously possible with other measurement techniques, such as from surface ships, buoys and aircraft. These measurements allowed oceanographers to infer the global distribution of the standing stock of phytoplankton for the first time.

A "proof-of-concept" experiment, CZCS also showed that satellite ocean color measurements could be reliably used to derive products such as chloroplyll and sediment concentrations and provided justification for future ocean color missions such as SeaWiFS and MODIS. The algorithms developed to analyze CZCS data were a considerable step forward from those available earlier. and included corrections for atmospheric backscatter, limb brightness and gelbstoffe. Ground truth campaigns led to empirical correlation of ocean color and biomass. CZCS also showed the need for good radiometric calibration and stability and the necessity of sufficient ground truth data to verify sensor and algorithm performance over time.

The CZCS Instrument

CZCS Data Collection

OBPG CZCS Data Processing

CZCS Calibration

CZCS Atmospheric Correction