Status of MODIS on-orbit calibration and characterization

Since launch, Terra MODIS has successfully operated for more than 13 years and Aqua MODIS more than 11 years. High quality science data products are continuously produced from sensor calibrated radiance and reflectance, or the Level 1 (L1B) data products, and distributed to worldwide users for a broad range of studies of the earth’s land, ocean, and atmospheric properties and their changes over time. MODIS observations are made in 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). The RSB are calibrated using data collected from its on-board solar diffuser and lunar observations, and the TEB are calibrated by an on-board blackbody (BB). On-orbit changes in the sensor’s spectral and spatial characteristics are monitored by an on-board spectroradiometric calibration assembly (SRCA). This paper presents an overview of both Terra and Aqua MODIS on-orbit operations, calibration activities, and methodologies applied from launch to present, and the current instrument status. It provides a summary of their radiometric, spectral, and spatial calibration and characterization performance. It discusses on-orbit changes in sensor characteristics and correction strategies applied to maintain the sensor calibration and level 1B (L1B) data quality, including lessons that could benefit future calibration efforts and other earth-observing sensors.