In my last post, I linked to a post at Steve Goddard's, grumbling about my comments at WUWT, where I linked to my earlier post showing a breakdown of total adjustment by states. A commenter picked up on New Hampshire, saying
"I particularly like nick’s new hampshire graph with a whole degree warming suddenly applied a few years ago. Their actual temps were obviously not cooperating."
Well, there is indeed a steep rise at about 1991:
The new graph shows that in 1991-2 there was a total rise of about 1°F made up about equally of a TOBS rise and a non-TOBS part. How could that happen? I investigated.
New Hampshire has just 5 USHCN stations, all operating to end 2013, at least. They are Bethlehem, Durham, First Connecticut Lake, Hanover and Keene. It turns out that the first and last underwent big changes about 1991-2. You can look up the relevant metadata here. Location is under the station-level tab, or location tab (map). TOBS is element level.
Bethlehem is actually a composite. The map below shows what happened. B1 lasted to 1 Jan 1992, and then reappeared as B2 about 4 km NE on 1 Jul 1992. Altitude dropped from 1380 ft to 1180 ft, or about 60 m, which would suggest about 0.7F rise in temp. However, the move also took the station out of town, and the cooling effect of that seems to have dominated.
But at the same time, the time of observation moved from 17.00 (warm bias) to 07.00 (cool). That would require an upward adjustment of order 1-2°F.
The total observed rise in adjustment for Bethlehem was 2.46°F, made up of 1.04 TOBS and 1.42 other.
For Keene, the relocation happened 28 Jan 91, and is recorded as moving 2.9 mi NW. Elevation rose 30 ft, but again, it was a move out of town. And again, the TOB changed from 17.00 to 7.00, requiring a warm adjustment.
The total rise for Keene was 3.34°F, made up of 2°F TOBS, and 1.34F other.
So the combined rise was 5.8°F, which divided by 5 in averaging gives indeed the observed NH rise in adjustment of 1.16°F.