Not long ago I wrote about how the satellite lower troposphere data diverged from the surface temperature trends some time earlier this century. I put it around 2006, just going by the charts. Tamino took a different approach and compared satellite data with that from thermometers on balloons (which I missed at the time, I'm embarrassed to say). It used to be just RSS that was the outlier, now with the latest UAH beta, both are.
There have been recent papers on the subject as well (see below), but so far the satellite researchers have not identified what is the cause (or not to my knowledge, yet).
