Foreword: I give thanks to Steve McIntyre for this analysis. Steve came to a conclusion similar to what I alluded to in my initial rebuttal where I said:
“For all I know, they could be comparing homogenized data from CRN1 and 2 (best stations) to homogenized data from CRN 345 (the worst stations), which of course would show nearly no difference.“
Steve does a superb job of deconstructing the memo’s undocumented results. Perhaps someday Dr. Thomas Peterson of NCDC will tell us how he did his analysis and show supporting data and methods. – Anthony
The Talking Points Memo
The NOAA Talking Points memo falls well short of a “full, true and plain disclosure” standard – aside from the failure to appropriately credit Watts (2009).
They presented the following graphic that purported to show that NOAA’s negligent administration of the USHCN station network did not “matter”, describing the stations as follows:
Two national time series were made using the same gridding and area averaging technique. One analysis was for the full data set. The other used only the 70 stations that surfacestations.org classified as good or best… the two time series, shown below as both annual data and smooth data, are remarkably similar. Clearly there is no indication for this analysis that poor current siting is imparting a bias in the U.S. temperature trends.
Figure 1. From Talking Points Memo.
Beyond the above sentence, there was no further information on the provenance of the two data sets. NOAA did not archive either data set nor provide source code for reconciliation.
The red graphic for the “full data set” had, using the preferred terminology of climate science, a “remarkable similarity” to the NOAA 48 data set that I’d previously compared to the corresponding GISS data set here (which showed a strong trend of NOAA relative to GISS). Here’s a replot of that data – there are some key telltales evidencing that this has a common provenance to the red series in the Talking Points graphic.
Figure 2. Plot of US data from www1.ncdc.noaa.gov/pub/data/cirs/drd964x.tmpst.txt
An obvious question is whether the Talking Points starting point of 1950 is relevant. Here’s the corresponding graphic with the 1895 starting point used in USHCN v2. Has the truncation of the graphic start at 1950 “enhanced” the visual impression of an increasing trend? I think so. Read the rest of this entry »
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