RSS Data Source is here
The RSS (Remote Sensing Systems of Santa Rosa, CA) Microwave Sounder Unit (MSU) lower troposphere global temperature anomaly data for March 2009 was published today and has dropped for the second month after peaking in January. The change from February with a value of 0.230°C to March’s 0.172°C is a (∆T) of -0.058°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
Like RSS, UAH was also announced today, on the blog of Dr. Roy Spencer here who is co-curator of the data with Dr. John Christy at the University of Alabama, Huntsville.
It showed a significant drop, more than double that of RSS:
The change from February with a value of 0.347°C to March’s 0.208°C is a (∆T) of -0.139°C
Recent UAH anomalies:
2009 1 0.304
2009 2 0.347
2009 3 0.208
Oddly, a divergence developed in the Feb 09 data between RSS and UAH, and opposite in direction to boot.
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.”
Looks like the data sets are converging now.
UPDATE: Barry Wise decided to contribute a plot in comments that I thought readers would find interesting.
The 1997/98 El Niño temperature spike seems to have had a long lasting effect that is dissipating. This graph shows what the trend was before the event and how the trend was affected by it. The dashed red line is the trend with all of the data and the purple is the trend based on the data before the area highlighted in red. Notice that there appears to be a decaying oscillation. If correct we’re in the third peak which is less than the previous two, and is much closer to the purple trend line.