Comparison between MODIS and AIRS/AMSU satellite-derived surface skin temperatures

Surface skin temperatures of the Level 3 products of MODIS Collection 5 (C5) and AIRS/AMSU version 5 (V5) have been compared in terms of monthly anomaly trends and climatologies over the globe during the period from September 2002 to August 2011. The MODIS temperatures in the 50° N-50° S region tend to systematically be ∼1.7 K colder over land and ∼0.5 K warmer over ocean than the AIRS/AMSU temperatures. Over high latitude ocean the MODIS sea surface temperature (SST) values are ∼5.5 K warmer than the AIRS/AMSU. The discrepancies between the annual averages of the two sensors are as much as ∼12 K in the sea ice regions. Meanwhile, the MODIS ice surface temperature product (MYD29E1D) over the ocean is in better agreement with AIRS/AMSU temperatures, showing a root mean square error of 3.7-3.9 K. The disagreement between the two sensors results mainly from the differences in ice/snow emissivity between MODIS infrared and AMSU microwave, and also in their observational local times. Both MODIS and AIRS/AMSU show cooling rates from -0.05±0.06 to -0.14±0.07 K 9 yr^-1 over the globe, but warming rates (0.02±0.12 -0.15±0.19 K 9 yr^-1) in the high latitude regions.