Recent progress in earth satellite data applied to marine activities

Although Seasat-A, the first Earth satellite dedicated to collection of data for oceanographic purposes, is not scheduled for launch earlier than May 1978, imagery and digital measurements from environmental (NOAA and GOES), meteorological (Nimbus), and earth resources survey (Landsat) satellites are being used for operational applications and/ or research studies in the marine area. Visible spectrum and thermal infrared data from the Scanning Radiometer (SR) and Very High Resolution Radiometer (VHRR) on the NOAA-polar-orbiting satellites, and from the Visible and Infrared Spin Scan Radiometer (VISSR) on the GOES (Geostationary Operational Environmental Satellite), are being used in a variety of ocean-oriented activities, principally but not exclusively in those relating to sea surface temperature mapping, sea ice monitoring, and detection of ocean currents and upwelling. New techniques of image and digital data processing and display, including time-lapse methods, have been developed recently. The Electrically Scanning Microwave Radiometer (ESMR) carried on the last two Nimbus spacecraft has been used operationally by the Navy because of its all-weather ice surveillance capability. Although not designed for these purposes, Landsat multi-spectral imagery has been used to demonstrate the feasibility of detecting ocean-scene color variations associated with such factors as water depth, sediment load, and chlorophyll concentration. The next Nimbus spacecraft, also planned for launch in mid-1978, is to carry the Coastal Zone Color Scanner (CZCS), a sensor system developed specifically for these kinds of tasks.