A new lower tropospheric temperature dataset using microwave sounding unit measurements

We have produced a new "TLT" (Temperature Lower Troposphere) dataset using data from the Microwave Sounding Unit (MSU). By using the same nadir-limb contrast method developed by Spencer and Christy(1, 2), but a physically consistent, model-based method of correcting for the drift in each satellite's local measurement time, we find that the global lower troposphere has warmed by ~0.19 C/decade over the past 26 years(3), slightly warmer than the 0.07 K/decade warming previously found by Christy et al. We find a more substantial difference in the tropics (20S to 20N), where our decadal trend of 0.19K is almost 0.2K/decade warmer than the previous Christy et al. results. Since we released our new findings, Christy and Spencer have constructed a new version of their results that shows more warming than earlier versions. We will discuss the differences between our findings and the updated Christy and Spencer results.

1. J. R. Christy, R. W. Spencer, W. B. Norris, W. D. Braswell, D. E. Parker, J. Atmos. Ocean. Tech. 20, 613 (2003). 2. R. W. Spencer, J. R. Christy, J. Clim. 5, 858 (1992). 3. C. Mears, F. Wentz, Science 11 August 2005 (10.1126/science.1114772.