AMPLIFICATION RATIOS: I was drawn into the dispute between Gavin Schmidt and Klotzbach et al. (see Pielke Sr.) over the latter paper's conclusion that the surface temperature record over land has a warm bias for the purpose of measuring global warming. I was cited in Klotzbach et al. as the source of a claim that the GISS model exhibits amplification over land of about 1.2. I should not have been cited, since all I did was report in an email to John Christy the average trop/surf trend in Gavin Schmidt's own GISS data pertaining to my 2007 surface temperature analysis. The information source, in other words, was Schmidt himself, not me; and in any case I did not provide it as a personal communication for the purpose of a journal article (which I did not know was being written). Phil Klotzbach and his coauthors have issued a correction on this point. In subsequent correspondence with Gavin Schmidt he reported to me that he had corrected an error his original IJOC archive and also that the GISS model classifies land differently than CRU so some of the 440 grid cells are actually over ocean in his model. He supplied me with the GISS landmask. I have recomputed the original results using the corrected data and the GISS landmask. The cosine-weighted amplification ratio over land is about 1.106 and over ocean is 1.602, where 'land' and 'ocean' are according to the GISS landmask applied to the 440 grid cells used in my 2007 paper.So in the paper we used an amplification of 1.2 based on calculations done earlier this year as described above. Subsequently, Gavin computed a value that was apples to our oranges and arrived at 0.95. Ross McKitrick just now re-computes a value that is more apples-to-apples and arrives at 1.1. We have shown that our conclusions are insensitive to the choice of 1.2 and 0.95 and you can easily conclude that using 1.1 instead won't matter either to the conclusions.
It is virtually certain that Gavin will contest the new number from McKitrick. Does it matter to me which one is judged to be most appropriate? From the standpoint of the analysis of Klotzbach et al., no. This sort of dispute won't be resolved on blogs, but in the peer reviewed literature where it belongs.
In other news, we've been informed by Ben Santer that our paper contains a referencing error (i.e., Santer et al. 2005 is used in the introduction where it should instead be Santer et al. 2000) and a typo (i.e., it reports a "p-test" rather than a "t-test"). We regret these errors, but certainly appreciate the close reading. We hope that the substance of the paper receives similar close attention. Once again, I hope that Gavin submits his critique of our paper's analysis and conclusions to the scientific literature, and if his work improves upon our work leading to better understandings, then good for science.