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The RSS (Remote Sensing Systems of Santa Rosa, CA) Microwave Sounder Unit (MSU) lower troposphere global temperature anomaly data for March 2009 was published yesterday and has dropped after peaking in January. The change from April with a value of 0.202°C to May’s 0.09°C is a (∆T) of -0.112°C.
Recent RSS anomalies
2008 10 0.181
2008 11 0.216
2008 12 0.174
2009 01 0.322
2009 02 0.230
2009 03 0.172
2009 04 0.202
2009 05 0.090
RSS (Remote Sensing Systems, Santa Rosa)
The RSS data is here (RSS Data Version 3.2)
Oddly, a divergence developed in the Feb 09 data between RSS and UAH, and opposite in direction to boot. UAH was 0.347 and RSS was 0.230
I spoke with Dr. Roy Spencer at the ICCC09 conference (3/10) and asked him about the data divergence.
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.”
It certainly looks like the data sets are converging now, with a scant difference in May of .047°C and that Dr. Spencer was right.