A recalibrated dataset is one where the calibration coefficients and/or the calibration algorithm has been updated relative to the operational calibration used to create the original satellite Level 1 datasets. The operational calibration is normally derived from pre-launch measurements and there are many instances where the pre-launch data/algorithm is insufficient to calibrate the sensor in orbit either due to changes in the satellite response while in orbit or due to problems with the pre-launch data/algorithm itself or both.