On Friday, 27 November 2009, the National Institute of Water and Atmospheric Research (NIWA) published a short press release at Scoop.
Under the heading “Combining Temperature Data from Multiple Sites in Wellington”, NIWA described in some detail the process of adjusting temperature readings when the weather station has been moved. By way of example, they cited Wellington, where, they said, the Thorndon weather recording station was moved in 1928 to Kelburn.
The Kelburn site is colder because it is about 120m higher than the Thorndon site. The process of combining data from various Wellington sites is illustrated below.
The day before, David Wratt was quoted in another NIWA press release:
Such site differences are significant and must be accounted for when analysing long-term changes in temperature. The Climate Science Coalition has not done this.
NIWA climate scientists have previously explained to members of the Coalition why such corrections must be made. NIWA’s Chief Climate Scientist, Dr David Wratt, says he’s very disappointed that the Coalition continue to ignore such advice and therefore to present misleading analyses.
But now, in a dramatic turnaround, they confess, in a written answer to a Parliamentary question, that this “example” of adjustments for the reason of altitude change was fiction.
They have not changed any temperatures for that reason at any station in the national “seven-station” series.
They were lying to us. They openly mocked Rodney Hide for not knowing about that sort of thing and scolded the inquiring scientists at the NZ Climate Science Coalition and falsely incited their supporters, such as the rabid warmers at Hot Topic, into making vicious attacks on the credibility of the NZ CSC and the Climate Conversation Group.
That’s all I have time for, but here’s the official Parliamentary answer (my emphasis):
Station adjustments are not made on the basis of elevation differences, either for Wellington or for any of the other six locations. Adjustments are calculated from comparisons of different stations’ records, as described in the NIWA document Creating a Composite Temperature Record for Hokitika.
Wellington is a special case where two sites, Thorndon and Kelburn, are very close to one another horizontally but with a large (approximately 120m) altitude separation. This does not occur for any of the other six locations in the “seven-station” series.
Temperature differences between Wellington sites correlate well with measurements, in many parts of the world, of temperature decrease with altitude. This “lapse-rate” effect has been used to confirm that the adjustment between Thorndon and Kelburn, calculated by inter-station comparison, would be expected from the altitude difference between the sites.
The slippery scientists at NIWA now admit that they didn’t use the altitude “lapse rate” method to calculate adjustments. They say it only “confirmed” adjustments made by another method.
So why did they ridicule us?
If NIWA have any credibility left it would be surprising.
How will Gareth Renowden respond to this? Is he getting the picture yet?