On Sunday I posted about the USHCN climate station of record in Tucumcari, NM highlighting its positive points since it has all the hallmarks of a well sited station with a long and uninterrupted record. But something was odd with the temperature record that didn’t quite make sense at first glance.
I also cross posted my report on Climate Audit since I always value additional input from the community there.
I noted that while this station is in fact well sited, and rates a CRN2, it has some oddities with it’s temperature record around the year 2000, something that looked like a step function to me.
Click for larger graph from NASA GISTEMP
Of course, even though this a truly rural station, 3 miles from the outskirts of town, Hansen and GISS apply adjustments to it anyway, which is part of the flawed “nightlights” algorithm incorrectly flagging this station for adjustment. Even though the adjustment makes the present cooler, it still seems misplaced given the station quality and history. Steve McIntyre said it best:
Here we have a rural station where there doesn’t seem to be any reason to adjust the temperature for population growth/UHI. But in this case, Hansen adjusts Tucumcari as though it were a city. Why is he even adjusting Tucumcari at all? (The “reason” is that its lights value removes it from the rural classification and it goes into the adjustment pool.) While Hansen sometimes seemingly cools rural stations in the past, for the GISS dset2 version here, he warms the past of the station (cools the present).
It’s more that this is a case of another unjustified adjustment by the “adjuster in chief” showing once again that the Hansen adjustments do not do what they are supposed to do – and the best that can be hoped from the Hansen adjustment program by users of this dataset is that the adjustments overall end up being pointless and random, rather than pointless and biased.
The adjustment by GISS looks like this:
Ok adjustments aside, the fact that there is a step at 2000 that remained unexplained until commenters on CA started looking at the data themselves. DaleC provided this graph: Read the rest of this entry »
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