The UAH and RSS global temperature anomaly data was posted while Steve and I were at the ICCC in New York. I’m unable to setup a graph for these while I’m on the road, so a short table will have to do:
RSS (Remote Sensing Systems, Santa Rosa)
RSS data here (RSS Data Version 3.2)
RSS Jan09 .322
RSS Feb09 .230
UAH (University of Alabama, Huntsville)
Reference: UAH lower troposphere data
UAH Jan09 .304
UAH Feb09 .350
Oddly, a divergence has developed, and opposite in direction to boot.
I spoke with Dr. Roy Spencer at the ICCC this morning (3/10) and asked him about the data divergence. Dr. Spencer had not yet seen that data, since he has been attending the conference. The data of course has been released by his associates and staff back at UAH. Here is what he had to say:
“I believe it has to do with the differences in how diurnal variation is tracked and adjusted for.” he said. I noted that Feburary was a month with large diurnal variations.
For that reason, UAH has been using data from the AQUA satellite MSU, and RSS to my knowledge does not, and makes an adjustment to account for it. I believe our data [UAH] is probably closer to the true anomaly temperature, and if I’m right, we’ll see the two datasets converge again when the diurnal variations are minimized.”
For layman readers that don’t know what diurnal variation is, it is the daily variation of temperature due to the variation of incoming solar radiation from rotation of the earth on its axis.
It looks like this: