Sensor calibration for multiple direction reflectance observations

Spectral and radiometric calibrations of a pointable airborne spectroradiometer called ASAS are discussed. A laboratory integrating hemisphere is used to characterize the radiometric respones of ASAS detectors. Radiometric responses are linear except for an initial build-up lag in response to low levels of radiance. Assuming radiometric stability in flight, raw ASAS digital counts can be transformed to absolute spectral radiance values with an uncertainty of 5.5 percent attributable to the laboratory calibration. The calibrations are being applied to radiometrically correct ASAS data acquired from multiple view directions over a tall grass prairie during the 1987 growing season.