The role of remote sensing in monitoring global bulk tropospheric temperatures

The IPCC AR4 (2007) discussed bulk tropospheric temperatures as an indicator of atmospheric energy content. Here, we examine the latest publications about, and versions of, the AR4 data sets. The metric studied is the trend that represents the average rate of atmospheric energy accumulation that relates to increased greenhouse gas forcing. For temperatures from microwave instruments, UAHuntsville's indicates the lowest trend for 1979-2009 and National Oceanic and Atmospheric Administration - Center for Satellite Applications and Research (NOAA-STAR)'s the highest, being slightly higher than Remote Sensing Systems' (RSS). Updated analyses using radiosonde data suggest RSS and STAR experienced spurious warming after the mid-1990s. When satellite and radiosonde data sets are considered, the global trends for 1979-2009 of the lower and mid-troposphere are +0.15 and +0.06 degrees C decade-1 respectively. Error ranges of these estimates, if we do not apply information that indicates some data sets contain noticeable trend problems, are at least +/- 0.05 degrees C decade-1, which needs reduction to characterize forcing and response in the climate system accurately.