Over on WUWT Barry had wanted a couple of “special” alignments of the v1 vs v3 comparison data.
His original statement was a 1900 start time, but in further comments he said the reason was to align the comparison with GIStemp and with Hadley products. As GIStemp “starts time” in 1880 and Hadley in 1850 (as I remember it) I’ve made two special comparison graphs of v1 vs v3 in aggregate aligned on those two start times.
The trend in any curve segment is fairly strongly influenced by the start and end points for a fit trend line, so these trends will be different both from each other and from the “all time” graph. As this First Differences based method is different from that used in both GIStemp and HadCRUT / CRUTEMP, the trend the difference found here will induce in those products is unknown.
So here are the two graphs:
For comparison, the “all data” graph again, but in a slightly different presentation with a trend line:
Don’t know if it will be of interest to anyone but Barry, but FWIW, I’ve made the custom cut graphs.
Can’t say I’m not cooperative ;-)