Calibration Of Satellite Sensors Research Articles

Radiometric calibration of satellite sensors in the visible and near infrared: History and outlook

Documentation for radiometric calibration of visible and near infrared sensors viewing the earth has been quite limited in the past. Recent quantitative use of satellite radiometry suggests the need for better information concerning instrumentation, estimation of atmospheric effects, and ground verification of satellite measured radiances. An example from the thermal infrared spectral region illustrates that analysis algorithms provide the link between satellite-derived results and the required accuracy of satellite calibration.

Impact of radiance variations on satellite sensor calibration

The intercalibration of digital data from different sensors depends on systematic and random variations in factors controlling recorded radiance. Theoretical expressions are presented which describe the impact of random variations in those factors which control radiance incident on the sensor. Means of measuring or estimating the impact of random variations on intercalibration factors are discussed. Means of detecting and calibrating for systematic effects are also discussed. We consider the optical-reflective, middle-infrared, and thermal infrared regions of the spectrum. An example is presented whereby NOAA-7 and NOAA-8 advanced very high resolution radiometer (AVHRR) radiance data, obtained over the same test fields, are shown to depend on the differences in view angles used by the two satellites.

Calibration of satellite sensors after launch

A simple and accurate method for the postflight calibration of satellite Visible Infrared Spin-Scan Radiometers (VISSR) is presented, and the results of inflight testing are reported. The calibration source for the VISSR with its effective wavelength of 610 nm is the radiance of sunlight, measured in calibrated reflectance units, scattered by the atmospheric gas above ocean which is far from land. Only the lowest 20 percent of the full-scale VISSR response is calibrated. VISSR testing aboard two geostationary operational evironmental satellites between 1980 and 1983 showed significant calibration coefficient variations of only + or - 12 percent and + or - 2 percent. Good agreement was found between values of aerosol optical thickness measured by VISSR and those measured from the ground.