Saturday, May 19, 2012


date: Mon, 20 Sep 1999 16:36:32 +0200
from: Inger Hanssen-Bauer <>
subject: contribution TAR
to: Hans von Storch <>

Dear Hans,

Please find, at the end of this mail, a possible contribution to chapter
10.6 in TAR. Our main messages are:

1) When developing empirical downscaling models, it is essential to use long
training periods.

2) The early twentieth century warming and the warming during the last 3
decades seem to be quite different with many respects. In Norway and
Spitsbergen, it is possible to explain most of the warming after the 1960s
by changes in the atmospheric circulation. The warming prior to 1940 cannot
be explained in this way.

We give 2 references. The second of these is presently published as an
�institute report� only (we will send you a copy if you want one), however
we are presently preparing a �journal version� of this work.

We send a copy of our suggested contribution also to Giorgi.

Best regards
Inger and Eirik

Suggested contribution to ch. 10.6 in TAR:

" Empirical downscaling models using SLP as the only predictor have been
developed both for Svalbard in the Atlantic sector of the Arctic
(Hanssen-Bauer and F�rland 1998), and for Norway (Hanssen-Bauer 1999). The
models could mainly reproduce the 20th century observed long-term trends and
decadal scale variability for precipitation. The models were also able to
reproduce temperature trends and variability after 1960. However, the early
twentieth century warming, which was especially pronounced in these areas,
was not satisfactorily modelled. One may thus conclude that, while the
warming in these areas during the last 3 decades mainly may be explained by
changes in the atmospheric circulation (at average increased zonal
circulation in winter and spring), the early twentieth century warming
cannot be explained in this way.

A conclusion of more general character, is that rather long data-series are
needed to ensure sufficient training and testing of empirical models. By
using only the last 30-50 yr of the data series, the performance of the
temperature models (Hanssen-Bauer and F�rland 1998, and Hanssen-Bauer 1999)
would apparently be satisfactory. Applying the models on earlier decades
reveal that this is not the case."


Hanssen-Bauer, I. and E.J. F�rland 1998: Long-term trends in precipitation
and temperature in the Norwegian Arctic: can they be explained by changes in
atmospheric circulation patterns? Climate Research, 10, 143-153.

Hanssen-Bauer, I. 1999: Downscaling of temperature and precipitation in
Norway based upon multiple regression of the principal components of the SLP
field. 1896-1997. DNMI-KLIMA report 21/99, 40 p, Norwegian Met. Inst.,
Box 43 Blindern, N-0313 Oslo

Inger Hanssen-Bauer Telephone: +47 22963172
Senior Scientist Switchboard: +47 22963000
Norwegian Meteorological Institute Telefax: +47 22963050
P.O.Box 43 - Blindern, N-0313 Oslo E-mail:

----- End of forwarded message from Inger Hanssen-Bauer -----

Hans von Storch

Institute of Hydrophysics
GKSS Research Center, Max-Planck-Strasse 1, PO Box,
21502 Geesthacht, Germany
Phone: +49 (4152) 87-1831, Fax: +49 (4152) 87-2832
: and
Home fax: +49 (4153) 582 522


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