Calibration of the Improved Stratospheric and Mesospheric Sounder. Part II: Optical Alignment, Spatial, and Pressure Modulator Calibrations

Abstract

In Part I the Improved Stratospheric and Mesospheric Sounder instrument and its calibration facility were described, and the results of the radiometric and spectral calibrations were presented. In Part II the remaining prelaunch calibrations are discussed. The optical calibrations include the procedure used to coalign the different spectral channels and the mapping of the resulting instantaneous fields of view. These maps revealed detailed stray light processes within the instrument. The remaining optical calibration is of angular motion of the instrument scan mirror. The pressure modulator calibrations consist of the filling procedures and algorithm validation, which allow the gas conditions within the modulator to be determined from the instrument telemetry. Some overall conclusions to the calibration process are drawn.