GHCN V1 vs V2 (V3 soon) Teaser

http://chiefio.wordpress.com/2012/05/10/ghcn-v1-vs-v2-v3-soon-teaser/

So what does this all mean?

At present, not too much. It does show that the impact of thermometer change is about 4 times that of the implied "global warming" signal being sought. It does show that the changes in the data via collection swamp the changes over time in a given set. It does show that v1 is very different from v2, largely due to the changing thermometers in the set. And it does show that v2 is a 'cooler' set of thermometers in the past than the ones used for v1. This, IMHO, highlights the "splice problem" inherent in all these data sets. The number of thermometers are small in the past, and grow over time (up until The Great Dying in 1990… for v2, the number of thermometers drops back to just 45 in 1993 ). Given that we see whole degree sized changes in the data from thermometer count changes of even lesser degree, how can we expect that plunge from 456 in 1991 to 45 in 1993 does not create a problem?…