Why do the following problems occur with the AATSR LST retrieval?
Poor cloud clearing The current AATSR cloud clearing scheme is optimised for use over oceans and its performance cannot be guaranteed over land. Land pixels may be wrongly flagged as cloud and when a pixel is flagged as cloud no LST retrieval is applied. Pixels flagged as cloud will be set to Cloud Top Temperature (currently the 11m BT) and Cloud Top Height (currently zero). Some AATSR images may contain pixels flagged as cloud, even when ground measurements show that the conditions were clear. It was always appreciated that the imperfections of cloud detection over land would be a limitation of the existing LST implementation, and ultimately a revised cloud clearing scheme optimised for performance over land needs to be defined. A “blocky” appearance with discontinuities at surface classification cell boundaries. No spatial smoothing of the LST has been included in the current implementation of the LST algorithm. Therefore the outline of the 0.5 degree cells used in the underlying lan
