Part 3 looks at a geographical distribution of how adjustments affect temperature trends. I have not dug down to the country level, although I wouldn’t rule it out for some future investigation. I did look at distribution by WMO region, but very little to see there. However, when I looked at distribution by lattitude band, a clear warming bias stood out for 24N to 44N (Figure 1).
Figure 1. Distribution by latitude band showing how adjustments affect the warming or cooling trends of temperature data sets.
As with Part 1
and Part 2
I immediately wanted to see the detail of the magnitude of adjustment. Figure 2 shows the bias very well – again for 24N to 44N. There is indeed a strong warming bias in the adjustments, with huge adjustments
of 1-2.5 degC/Century.
Figure 2. A breakdown of the magnitude of temperature trend adjustment by latitude band.
There are only very slight biases in other latitidue bands, if they are detectable at all. I was tempted not to even show them, however here are the graphs for 64N to 90N (Figure 3) where there are cooling adjustments, and the bands either side of the Equator – 24N to 24S (Figure 4). There is also a cooling bias in Equator to 24N. Again these are subtle.
Figure 3. Adjustments for 64N to 90N Figure 4. Adjustments for bands spanning the Equator.
I suppose until I put all this together I am not sure of the significance this bias in adjustment. At present I cannot say it is intentional that so many small warming biases have crept in with each adjustment, but I am more sure than ever that the adjustments now must be justified.
So where next with this? Well, at the moment I have a hankering to examine the effect of the major fall off of stations after 1990, but I guess I’ll have to play with the data for a while to see what it shows.
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