Aqua MODIS has successfully operated for more than 20 years and continuously generated a wide range of data products to enable and support the remote sensing community and users worldwide for their studies of the Earth’s system. Although it is currently operated in its extended mission phase, Aqua MODIS continues to make high quality global observations of the Earth’s surface and its on-board calibrators (OBC) remain capable of performing their design functions, providing essential calibration data sets to help monitor on-orbit changes in sensor responses. In this paper, we provide an overview of Aqua MODIS on-orbit calibration methodologies for both reflective solar bands and thermal emissive bands, illustrate its on-orbit performance over 20 years using examples derived from OBC measurements, lunar observations, and Earth view response trends, and describe various calibration improvements made over its entire mission. We focus on several issues identified since launch, such as solar diffuser degradation, electronic crosstalk, and on-orbit changes in sensor response versus scan-angle, and discuss the approaches developed to mitigate their impact on sensor calibration quality.
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