date: Wed, 15 Sep 1999 14:37:20 +1000
from: "Whetton, Peter" <peter.whettonatXYZxyz.csiro.au>
subject: RE: spectral nudging
to: 'Hans von Storch' <Hans.von.StorchatXYZxyzs.de>, jhcatXYZxyz.dk
Dear Hans and Jens,
I don't know much about nudging, but I do know that our regional modellers
here use some weak (non-spectrally based) nudging in their climate runs with
the CSIRO regional model. Some nudging in the direction of the host GCM is
done within the domain because of the large size of the domain used. The
technique was found to improve simulation of interannual rainfall
variability in the tropics. There is a brief description of the method in:
McGregor, J. L., Katzfey, J. J., and Nguyen, K. C. (1998). Fine resolution
simulations of climate change for Southeast Asia: final report for a
research project commissioned by Southeast Asian Regional Committee for
START (SARCS). Aspendale, Vic.: CSIRO Atmospheric Research. vi, 15, 35 p.
I can send this report to you, Jens, if you haven't already got it.
From: Hans von Storch [mailto:Hans.von.Storch@gkss.de]
Sent: Monday, 13 September 1999 21:08
Subject: Re: spectral nudging
Reply to 'Jens Hesselbjerg Christensen':
Dear Jens, thanks for this, but I don't think that you are right.
Bennert has certainly NOT contributed to the spectral nudging
approach, as he definitely opposes the concept. Spectral
modelling and nudging is not the same.
Indeed, when I presented this material both an DMI and SMHI
(including Nils Gustafsson) it was
considered by your colleagues as "new", but that Rene Laprise
had something along this lines presented at talks. Also Rene
acknowldeged that it was - for him - unpublished material.
Also the review process at MWR indicated no use in the climate
community so far. Could it be that you simply have misunderstand
I certainly consider this material relevant for the IPCC
process. I am a bit irritated about you phrasing the decision
not to include material of this sort as your personal
decision. At least one lead author -me- considers it relevant.
I think this debate has some relevance for the LA-group as
a whole. Therefore I am cc'ing it to the joint e-mail box.
Med venlige hilsner
>From jhcatXYZxyz.dk Mon Sep 13 12:55:27 1999
>Date: Mon, 13 Sep 1999 12:55:13 +0200
>From: Jens Hesselbjerg Christensen <jhcatXYZxyz.dk>
>Subject: Re: spectral nudging
>To: Hans von Storch <Hans.von.StorchatXYZxyzs.de>
>Organization: Danmarks Meteorologiske Institut
>X-Mailer: Mozilla 3.01 (X11; I; IRIX 6.3 IP32)
> >I would like to try to contribute further to your enlightment on
>spectral nudging and similar approaches to limited area modelling. One
>other model that is well tested and used for NWP purpose is the ALADAIN
>model of Meteo France. This model is based on ideas of Jean-Fransoir
>Geleyn and Bennert Machenhauer. Even HIRLAM has a spectral equivalent
>version based on a paper by Machenhauer and Haugen. This version is used
>for various tests mainly by Nils Gustafsson in Norrkoping.
>I fully appreciate your interest in these matters, but to be honest, i
>have not dragged these models into our discussion, since I have not
>found their application relevant in the IPCC context. Indeed I would
>have mentioned to you in a refereeing procedure, that quite a
>substantial work along those line have been carried out in these
>Hans von Storch wrote:
>> you possibly remember that I have made some experiments with
>> the spectral nudging technique in RCMs. I thought it was a new
>> technique, with some similarity to Sasaki's approach. Filippo
>> indicated that he had reviewed a paper along these lines, but could
>> unfortunately not find his copy. My coworkers and I had in the
>> meantime produced a report:
>> von Storch, H., H. Langenberg and F. Feser, 1999: Long-wave forcing for
regional atmospheric modelling. GKSS 99/E/46 report
>> in which we claim to have suggested a new technique and demonstrated
>> its skill.
>> Now we got reviews from Mon Wea Rev, and it turns out that the
>> technique is definitely NOT new. Even the name "spectral nudging"
>> has been used previously:
>> Waldron, K. M., J. Peagle and J.D. Horel, 1996: Sensitivity of a
spectrally filtered and nudged limited area model to outer model options.
>> Mon. Wea. Rev. 124, 529-547
>> (Otherwise the reviews yielded no surprises.)
>> Also, NMC seems to have something along these lines in its
>> analysis tools.
>> It seems that we have to rewrite parts of Subsection 5 of
>> our chapter. Frankly, I am a bit surprised to learn that seemingly
>> nobody in the RCM community, I spoke to, had taken notice of this
>> important paper. It deals just with a weather episode and can not
>> make any "climate" claims, but technically it fits very well.
>> 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
>> WWW: http://w3g.gkss.de/G/Mitarbeiter/storch/
>> e-mail: storchatXYZxyzs.de and firstname.lastname@example.org
>> Home fax: +49 (4153) 582 522
>> FINALLY PUBLISHED: VON STORCH & ZWIERS, STATISTICAL
>> ANALYSIS IN CLIMATE RESEARCH, CAMBRIDGE UNIVERSITY PRESS
>Jens Hesselbjerg Christensen
>Danish Climate Centre
>Danish Meteorological Institute
>Lyngbyvej 100, DK-2100 Copenhagen �
>Phone: +45 39 157 500
>Direct phone: 39 157 428
>Fax: 39 157 460
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
e-mail: storchatXYZxyzs.de and email@example.com
Home fax: +49 (4153) 582 522
FINALLY PUBLISHED: VON STORCH & ZWIERS, STATISTICAL
ANALYSIS IN CLIMATE RESEARCH, CAMBRIDGE UNIVERSITY PRESS