Estimating afternoon MODIS land surface temperatures (LST) based on morning MODIS overpass, location and elevation information

The MODerate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra and Aqua satellites is a critical tool for providing daily estimates of land surface temperature (LST). Terra launched in late 1999 has a morning (AM) overpass, whereas Aqua launched in early 2002 has an afternoon (PM) overpass. Generally, LST is expected, under cloudless conditions, to be warmer in the early afternoon than the morning due to the link between maximum skin temperature and solar insolation peak time, therefore the Aqua PM LST is likely to be closer to the maximum daily LST than that acquired from Terra. This letter investigated differences between the Aqua MODIS PM and Terra MODIS AM LST estimates over a range of land cover classes, locations, and dates, across Canada. The aim was to develop a simple adjustment which can be applied to Terra AM LST estimates to approximate a "synthetic" Aqua PM LST product from 2000 to mid-2002, thereby providing a seamless afternoon MODIS LST product from 2000 to 2006. Results indicate that there are statistically significant differences between the AM and PM LST ranging from OYC to 3.2 degrees C depending on cover type, and between 1.2 degrees and 5.0 degrees depending on time of year. On average, over 90% of the variation observed in the PM record can be explained by the AM LST, land cover types and location.