page_title: Coastal zone color scanner
section_title: Technical details
hierarchical_section_title: Coastal zone color scanner / Technical details
caption_attribution_description: Artist rendering of the general design of the Nimbus series of satellites. The solar-panel “wings” move throughout the day to track the Sun during the daylight part of the satellite’s orbit. The 10-foot-tall satellite has the attitude control system on top, separated from a 5-foot-diameter “sensory ring” (center) with scaffolding. The sensory ring holds the batteries and electronics for each of the sensors that are mounted underneath the ring (bottom).
context_page_description: The coastal zone color scanner was a multi-channel scanning radiometer aboard the Nimbus 7 satellite, predominately designed for water remote sensing. Nimbus 7 was launched 24 October 1978, and CZCS became operational on 2 November 1978. It was only designed to operate for one year, but in fact remained in service until 22 June 1986. Its operation on board the Nimbus 7 was limited to alternate days as it shared its power with the passive microwave scanning multichannel microwave radiometer.
  CZCS measured reflected solar energy in six channels, at a resolution of 800 meters. These measurements were used to map chlorophyll concentration in water, sediment distribution, salinity, and the temperature of coastal waters and ocean currents.
  CZCS lay the foundations for subsequent satellite ocean color sensors, and formed a cornerstone for international efforts to understand the ocean's role in the carbon cycle.
context_section_description: The CZCS instrument was manufactured by Ball Aerospace & Technologies Corp..
  Reflected solar energy was measured in six channels to sense color caused by absorption due to chlorophyll, sediments, and gelbstoffe in coastal waters. The CZCS used a rotating plane mirror at a 45-degree angle to the optic axis of a Cassegrain telescope. The mirror scanned 360 degrees but only the 80 degrees of data centered on nadir were collected for ocean color measurements. The instrument viewed deep space and calibration sources during the remainder of the scan. The incoming radiation was collected by the telescope and divided into two streams by a dichroic beam splitter. One stream was transmitted to a field stop that was also the entrance aperture of a small polychromator. The radiance that entered the polychromator was separated and re-imaged in five wavelengths on five silicon detectors in the focal plane of the polychromator. The other stream was directed to a cooled mercury cadmium telluride detector in the thermal region (10.5–12.5 micrometer). A radiative cooler was used to cool the thermal detector. To avoid sun glint, the scanner mirror was tilted about the sensor pitch axis on command so that the line of sight of the sensor was moved in 2-degree increments up to 20 degrees with respect to the nadir. Spectral bands at 0.443 and 0.670 micrometers centered on the most intense absorption bands of chlorophyll, while the band at 0.550 micrometers centered on the "hinge point," the wavelength of minimum absorption. Ratios of measured energies in these channels were shown to closely parallel surface chlorophyll concentrations. Data from the scanning radiometer were processed, with algorithms developed from the field experiment data, to produce maps of chlorophyll absorption. The temperatures of coastal waters and ocean currents were measured in a spectral band centered at 11.5 micrometers. Observations were made also in two other spectral bands, 0.520 micrometers for chlorophyll correlation and 0.750 micrometers for surface vegetation. The scan width was 1556 km centered on nadir and the ground resolution was 0.825 km at nadir.
caption: An artist's rendering of the Nimbus satellites' design
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