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Old 20-11-2009, 08:06 PM   #46
the nine
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From: Phil Jones
To: Gil Compo
Subject: Re: Twentieth Century Reanalysis preliminary version 2 data - One other thing!
Date: Tue Nov 10 12:40:26 2009

One other good plot to do is this. Plot land minus ocean. as a time series.
This should stay relatively close until the 1970s. Then the land should start moving away
from the ocean.
This departure is part of AGW. The rest is in your Co2 increases.
These will do for my purpose. I won't pass them on. I am looking forward to the draft
paper. As you're fully aware you're going to have to go some ways to figuring out what's
causing the differences.
You will have to go down the sub-sampling, but I don't think it is going to make much
difference. The agreement between CRU and GISS is amazing good, as already know. You ought
to include the NCDC dataset as well.
[1] the ERSST3b dataset.
In the lower two plots there appear to be two types of differences, clearer in the
NH20-70 land domain.
The first is when reanl20v2 differs for a single year (like a year in the last 1960s, 1967
or 1968) and then when it differs for about 10 years or so. It is good that it keeps coming
back. For individual years there are a couple of years in the first decade of the 20th
century (the 1900s).
The longer periods are those you've noticed - the 1920s and the 1890s. There is also
something up with the period 1955-65 and the 1970s. The 1920s seems to get back then go off
again from about 1935 to early 1940s. Best thing to try and isolate some of the reasons
would be maps for decades or individual years. For the 1920s I'd expect the differences to
be coming from Siberia as opposed to Canada. I think the 1890s might be just down to
sparser coverage. The 1890s is the only period where the difference brings your pink line
back towards the long-term zero. All the others have the pink line more extreme than the
HadCRUT3/GISS average.
Rob Allan just called. I briefly mentioned this to him. He suggested maps of data input
during these times. He also suggested looking at the spread of the ensembles. Your grey
spread is sort of this, but this is a different sort of ensemble to what Rob implied you
might have?
One final thing - don't worry too much about the 1940-60 period, as I think we'll be
changing the SSTs there for 1945-60 and with more digitized data for 1940-45. There is also
a tendency for the last 10 years (1996-2005) to drift slightly low - all 3 lines. This may
be down to SST issues.
Once again thanks for these! Hoping you'll send me a Christmas Present of the draft!
At 20:45 09/11/2009,
clear evidence of suppressing thr facts to suit their agenda..carbon tax!
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