Wednesday, December 9, 2009
The lack of transparency is the problem. The adjustments should be completely disclosed for all stations including reasons for those adjustments. You have to be careful drawing conclusions without knowing why the adjustments were made. It certainly looks suspicious. In Torok, S. and Nicholls, N., 1996, An historical temperature record for Australia. Aust. Met. Mag. 45, 251-260 which I think was the first paper developing a “High Quality” (not sure that is how I would personally describe it given the Australian data and station history but moving along…) one example of adjustments is given for 224 stations used in that paper and they are for Mildura. The adjustments and reasons (see p.257):
“Detect” refers to use of the Detect program (see paper). The “<” symbol indicates that the adjustment was made to all years prior to the indicated year. The above gives an idea of the type of adjustments used in that paper and the number of adjustments made to data. For the 224 candidate stations 2,812 adjustments were made in total. A couple of points, the adjustments are subjective by their very nature. Use of overlapping multi station data can assist. I have concerns about the size of the errors these multiple adjustments introduce but I am certainly no expert. I wonder what the error bar is on the final plot when we are talking of average warming in the tenths of a degree C over a century. The stations really never were designed to provide the data that it is being used for but that is well known. My point is without the detailed station metadata it might be too early to draw a conclusion. This is why we need to know what were the adjustments made to each station and the reasons. Surely this data exists (if it doesn’t then the entire adjusted data series is useless as it can’t be scrutinised by other scientists – maybe they did a CRU with it!?) and if they do why are they not made public or at the very least made available to researchers. Have the data keepers been asked for this? I am assuming they have.
<1989 -0.6 Move to higher, clearer ground
<1946 -0.9 Move from Post Office to Airport
<1939 +0.4 New screen
<1930 +0.3 Move from park to Post Office
1943 +1.0 Pile of dirt near screen during construction of air-raid shelter
1903 +1.5 Temporary site one mile east
1902 -1.0 Problems with shelter
1901 -0.5 Problems with shelter
1900 -0.5 Problems with shelter
1892 +1.0 Temporary site
1890 -1.0 Detect
Since writing that I see that the IPCC adjusted their data from a -0.7C downward trend per century for Darwin to +6C upward trend per century! There could be no possible reasonable explanation for such an "adjustment". It will be very interesting to see what detailed examinations of other IPCC data reveal.