USHCN – U.S. Historic Cimate Network.
I had intended to make a study comparing USHCN (what was used by GIStemp up until just a couple of months ago, and which “cut off” in May of 2007, leaving only the limited GHCN – Global Historic Climate Network, stations) to the newer USHCN Version2 (that I will shorten to USHCN.v2). The question I was going to answer was “Did my ‘eyeball’ inspection of the data that looked like it had an induced warming trend stand up to analysis?” Well, in comments over on Wattsupwiththat, it looks like another person is already doing that work, and finding an induced warming trend from the “update”.
Mike McMillan (17:28:30) :
I’ve completed USHCN vs USHCN version 2 blink comparison charts for Wisconsin. As with the Illinois charts, the majority of stations had their raw data adjusted to show more warming by lowering the temperatures in the first half of the 20th century.
That brings the raw data more in line with the GISS homogenized versions. I haven’t blinked the original GISS with the new homogenized charts yet, but I’d bet a nickle they’ll show even more warming.
Wisconsin original USHCN raw / revised raw data –
Illinois original raw / revised raw –
Revised raw data. Oxymoron?
I’ll still do my comparison study (as confirmation of his findings, if nothing else. Independent confirmation is always a good thing) but just with a bit less urgency. The charts in his link have a caption that implies this is the GIStemp STEP0 output (which merges GHCN with USHCN or USHCN.v2) so would be the “blended” data for those stations in both. Luckily, with only 136 USA stations remaining in GHCN, the odds of any one of these being that station or two in that state become quite small. For all practical purposes, you can treat these graphs as a fairly clean USHCN vs USHCN.v2 comparison, even if they are not completely pristine comparisons of the data sets directly.
At least now we know that the decision by NASA / GISS to “put back in the USA thermometers” was not exactly a benevolent act… Until just a while ago, GIStemp ran on USHCN (which had a data cut off in May of 2007. This left only GHCN to cover the last 3 years and had such effects as leaving only 4 thermometers in California mostly on the beach and near L.A.) Well, OK, they put the USA back in, but it sure looks like they had to re-cook the data first.
So now instead of only 1176 thermometers surviving into 2009 in GIStemp, all from GHCN, we will have them plus a couple of thousand in the USA, but with those USA thermometers having been “adjusted” to show sufficient warming…
I need to re-run some of the thermometer count reports, but with USHCN.v2 data in the system, and see what it does to the USA numbers. So now it looks like we’ll have more than 4 thermometers in California, but though they won’t be “on the beach”, they will be near a sun lamp … ;-)
BTW, I’d heard a press release discussed where NOAA / NCDC says that a new revision of GHCN is due out near February that uses the same “enhanced” “corrections” applied in USHCN.v2. So watch out for a New Improved, and much Warmer Global Temperature History coming to a computer model near you!
Call me old fashioned, but I really liked it better when my history did not keep changing and past temperatures did not require frequent re-writing…