Thursday, December 29, 2011


date: Mon, 7 Sep 2009 00:13:56 +0100 (BST)
from: "Tim Osborn" <>
subject: New Zealand summer temps

Hi Phil,

just a quick Q before I go to bed!

I've just updated the IPCC paleo chapter Southern Hemisphere plot where we
showed, amongst other things, Ed Cook's New Zealand TRW reconstruction,
with CRUTEM2v Jan-Mar smoothed temperatures.

For my update I've used CRUTEM3v, expecting them to be rather similar but
with a few more years on the end.

But the pre-1930 temperatures are now very different, being much cooler
(by > 0.5 degC for a 25-year low-pass mean) in CRUTEM3v than CRUTEM2v.
Previously they had been, on average, near or even above the 1961-1990
mean, now they're at -0.5 degC.

Is this a result of some homogenization work on New Zealand summer temp
data? Or just some random artefact of minor changes somewhere?



Dr. Tim Osborn
RCUK Academic Fellow
Climatic Research Unit
School of Environmental Sciences
University of East Anglia
Norwich NR4 7TJ, UK

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