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 degrees N-50 degrees S region tend to systematically be similar to 1.7K colder over land and similar to 0.5K warmer over ocean than the AIRS/AMSU temperatures. Over high latitude ocean the MODIS sea surface temperature (SST) values are similar to 5.5K warmer than the AIRS/AMSU. The discrepancies between the annual averages of the two sensors are as much as similar to 12K 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 3.7-3.9K. 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 +/- 0.07K9yr(-1) over the globe, but warming rates (0.02 +/- 0.12-0.15 +/- 0.19K9 yr(-1)) in the high latitude regions.