Calibrating a system of satellite instruments

Abstract

Satellite instrument calibration is the essential and fundamental process to convert the Earth view sensor response in voltage and counts to radiance and reflectance. Calibration accuracy directly affects the quality of the satellite Level 1b data used for numerical weather prediction and climate change detection. Therefore, ideally all calibration should be made traceable to the International System of Units (SI). However, since each satellite instrument is calibrated separately with different methodologies and at different times in history, there is often disagreement between satellite measurements which could cause errors in both weather and climate applications. This chapter provides an overview of the fundamentals of satellite instrument calibration and reviews some of the challenges in establishing consistent satellite measurements across a system of satellites. Examples are used to demonstrate the progress made in inter-satellite calibration in recent years to support climate change detection studies and to contribute to the Global Earth Observation System of Systems (GEOSS).