Calibration data models for the Landsat 7 ETM + internal calibrator

摘要

The Landsat-7 ETM+ incorporates three on-board calibration devices: (1) an internal calibrator, (2) a partial aperture solar calibrator and (3) a full aperture solar calibrator. The internal calibrator consists of two tungsten lamps and optical and mechanical components to transfer the light to the primary and cooled focal planes. In the present contribution we analyze the ETM+ internal calibrator signal in several spectral bands and model them functionally using several instrument-state quantities available in the Landsat-7 telemetry. Models were tested and compared in terms of their complexity, explanatory power and fit to the data. The intent of such models is to provide a way to correct for the internal calibrator instabilities and allow for its more precise usage in calibrating ETM+ data on-orbit. Some of the computer models we developed can be accessed interactively on the World Wide Web.