Thursday, April 12, 2012

3362.txt

cc: Sakari Uppala <ersatXYZxyzwf.int>
date: Mon Mar 8 10:37:31 2004
from: Phil Jones <p.jonesatXYZxyz.ac.uk>
subject: Re: November 1981 in CRUTEM2v, ERA-40 and NCEP
to: Adrian.SimmonsatXYZxyzwf.int

Adrian,
Found the problem and it is in the CRU data. It is also in World Weather Records
and likely in the GHCN dataset at NCDC as well. We are going to trawl through some
files for Turkey that we have and see if we can find the correct data in them. I recall
putting
this data in so maybe that was wrong as well. The data we have for Nov 81 looks like
another month - maybe Sept or Oct.
If we have to contact Turkey it may take a little time to get the right data. Best to
omit that month for the time being. Also, Turkey has a lot of missing data in 1981 for
some reason. Will try and infill that at the same time.
Cheers
Phil
Adrian,
I'll look into this. I vaguely recall some odd months during the 1980s which we
discovered in some comparisons then. I'll have to go back to some older files
and check with some more recent Turkish data we've received.
During that time we were putting the CLIMAT messages in by manual means. We've since
received the World Weather Records for Europe (RA6, so including Turkey), so any values
should have been replaced by these numbers directly from the country.
It may take me a few hours to get to the bottom of this.
Cheers
Phil

At 12:36 06/03/2004 +0000, Adrian Simmons wrote:

Phil
I found a few hours to work on the reanalysis/CRU comparisons this morning, and decided
to plot the differences between CRU and ERA-40, and between CRU and NCEP,
month-by-month. Basically, it showed ERA-40 in a good light, assuming CRU to be truth.
However, November 1981 over "Europe" was anomalous, as can be seen in the attached time
series. The NCEP curve is hidden beneath the ERA-40 curve for this month: both are
unusually different from CRUTEM2v. For ERA-40, it's the largest discrepancy in the
series.
I thus plotted out values for each of the grid boxes that go into the average for this
month. The problem is confined to the south-east of the domain - strictly Asian boxes
rather than European ones (though we have all of Turkey as a Member State!). Here are
the anomalies relative to 1961-1990 for the three boxes with the largest discrepancies:
Lat: 45N-40N Lon: 30E-35E CRUTEM2v: 7.75 ERA-40: -1.39 NCEP: -1.14
Lat: 40N-35N Lon: 30E-35E CRUTEM2v: 6.85 ERA-40: -1.69 NCEP: -2.66
Lat: 40N-35N Lon: 35E-40E CRUTEM2v: 4.28 ERA-40: -1.59 NCEP: -2.76
As you can see, it is the CRUTEM2v values that are the most anomalous.
I hope I haven't made a mistake in my processing of the CRUTEM2v data. Assuming not, I'd
appreciate your comments on this. Are you aware of any problem with the data in this
region?
Best regards
Adrian
--
--------------------------------------------------
Adrian Simmons
Head of Data Division
European Centre for Medium-Range Weather Forecasts
Shinfield Park, Reading, RG2 9AX, UK
Phone: +44 118 949 9700
Fax: +44 118 986 9450
--------------------------------------------------

Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email p.jonesatXYZxyz.ac.uk
NR4 7TJ
UK
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