There is some interesting news in the October RSS global temperature anomaly numbers. We are still cooler than one year ago, and the 12 month trend continues to drop. But, the big news is that RSS has revised their dataset to reflect improvements in quality control.
Version 3.1 of the TLT Lower Troposphere data has been replaced with version 3.2 You can view both datasets:
Here is a graph showing the two dataset plotted simultaneously. No October data exists for Version 3.1 For the most part, it looks like Version 3.2 has warmed a bit more in the past for the 1979-1990 period, slightly reducing the overall trend:
Here is what RSS says about this change
Version 3.2 simplifies and improves a number of processing steps. The changes are:
- Target Factors and Scene Temperature Factors are determined entirely during the merging process using monthly gridded data. In V3.0 and V3.1, the target factors were determined offline using monthly global averages, and then applied to the monthly gridded data. The new methods streamline the data processing, and result in very small changes in long-term trends.
- A more comprehensive analysis of the intersatellite differences has been performed. As a result of this study, we have identified several satellite-months of data that appear to be inconsistent with measurements from other satellites during the same time period. These typically occur near the beginning or end of a satellite’s life. These data have been removed from processing.
- We reduced the systematic bias that occurs due to spatial-derivative effects in the TLT extrapolation process that can be large at high latitudes. The effects of this bias are particularly large near Antarctica. (see Section 2c in the preprint for a discussion)
- Quality control for individual TLT measurements has been improved, which results in less radio frequency interference (RFI). RFI induced artifacts were previously visible in our TLT monthly maps, particularly near Ascension Island in the tropical Atlantic Ocean.
For more details:
|Changes from RSS TLT Version 3.1 to Version 3.2|
|Changes from RSS Version 3.0 to RSS Version 3.2|
The changes listed above result in a slight change in the decadal trend, from 0.183°C/decade to 0.180°C/decade. A difference of a mere 0.03°C
Update 11/09: The graph above is from RSS PDF Changes from RSS TLT Version 3.1 to Version 3.2 and represents data from 70.0S to 82.5N. In comments it’s been pointed out that the current RSS 3.2 raw TLT data for the same latitude span shows a .157C/decade trend and elsewhere on RSS own website they show a .158C/decade trend for the same data. We hope to get an answer from RSS on Monday to help resolve this discrepancy.
As for the monthly data for October:
The RSS (Remote Sensing Systems of Santa Rosa, CA) Microwave Sounder Unit (MSU) lower troposphere global temperature anomaly data for October 2008 was published Friday and has remained essentially unchanged, even with the new data version, from September with a value of 0.241°C (V3.1) for a change (∆T) of -0.06°C
2008 1 -0.070
2008 2 -0.002
2008 3 0.079
2008 4 0.080
2008 5 -0.083
2008 6 0.035
2008 7 0.147
2008 8 0.146
2008 9 0.241 (V3.1)
2008 10 0.181 (V3.2)
The October 2008 number is 0.181°C
The RSS data is here (RSS Data Version 3.2)