Roughness length zo
Hans Burchard
thanks a lot for your mail below regarding the surface roughness length to
which you attached the following paper with observations from the Central
Baltic Sea:
Carlsson, Bj�rn, Yiannis Papadimitrakis, Anna Rutgersson, 2010: Evaluation
of a Roughness Length Model and Sea Surface Properties with Data from the
Baltic Sea. J. Phys. Oceanogr., 40, 2007�2024.
doi: http://dx.doi.org/10.1175/2010JPO4340.1
I copy this reply to the GOTM list, because I think that many are
interested in this issue.
All the best,
Hans.
> Dear Hans
>
> I read the messages that GOTM users receive, occasionally. So, I have seen
> a few messages regarding the use of Charnock's relation and how several
> people address the zo evaluation problem, etc. I also saw the various
> values of Charnock's constant proposed there.
>
> In my view, Charnock's theory does not address the real physics of zo
> parameter. You may find useful, the attached article, published in JPO, in
> 2010, that came out as a result of a Ph.D Dissertation of a student of
> mine
> from the University of Uppsala, while I was there during a sabbatical
> leave. Again, Charnocks relationships (in my view) aught to be abandoned.
>
> Sincerely
>
> Yiannis Papadimitrakis
> Professor Emeritus
>
--
Hans Burchard
Leibniz Institute for Baltic Sea Research Warnemuende
Dept. for Physical Oceanography and Instrumentation
Seestrasse 15
D-18119 Rostock-Warnemuende
Germany
Tel. : +49 - 381 - 5197 -140
Fax : +49 - 381 - 5197 -114
web : http://www.io-warnemuende.de/hans-burchard-en.html
E-Mail: hans.b...@io-warnemuende.de
skype : hans.burchard
Adolf STIPS
Dear Yiannis,
thank you for the interesting paper.
(and may be you remember that we met at Ispra?)
Unfortunately we cannot abandon the Charnock relationship for determining z0,
within GOTM, as we cannot apply your proposed parameterizations based on wave age or swell
ratio, as we simply do not have these parameters available in GOTM.
(Wave model or measurements would be needed)
By the way, are you aware of the z0 measurements from Gemmrich&Farmer?
The are specifically addressing the z0 problem under breaking waves in the open sea,
so I wonder that you have not cited them?
In my opinion Hasse a few years ago made a nice remark about the Charnock relation:
"There are only two types of people, they overly optimistic who think "Charnock" explains
everything and the overly pessimistic who think it does not explain anything. None of them is right."
Best regards, Adolf
On Jan 26, 2012, at 6:35 AM, Hans Burchard wrote:
> Dear Yiannis,
>
> thanks a lot for your mail below regarding the surface roughness length to
> which you attached the following paper with observations from the Central
> Baltic Sea:
>
> Carlsson, Björn, Yiannis Papadimitrakis, Anna Rutgersson, 2010: Evaluation
Hans Burchard
Happy new & turbulent year!
The z0 debate points at a real research problem. In all those cases
where our quantitative knowledge of processes and parameters is
dramatically weak, the scatter so large, we can see it as being bad.
But as researchers we have to see it as the contrary - a chance for
real research, our favorite hobby.
A REAL problem! I have already contacted Sandro Carniel with respect
to whether it could make sense to organize a small dedicated team with
only one problem: a better understanding of z0, "the Charnok issue",
and the general sea surface turbulence.
At the sea surface we have mainly three sources of turbulence:
- the "linear" waves and their generic shear, the
- overall current shear in the upper water column, and
- the breaking waves.
These processes control the major scales of mixing and have
consequences for gas and heat exchange, i.e. climate-change issues.
I think there is so many valuable work done already that we
have a good chance today to go (on their shoulders) one step further
and concentrate on the above one and only question.
One basis should be the corrected physical understanding of turbulence
in the sense given in two papers here:
http://export.arxiv.org/api/query?search_query=all:baumert+AND+helmut
We could combine with the works by Papadimitrakis, Banner, Craig, Stips,
W�est, Prandke, Farmer, Gemmrich, et al. (please don't crucify me for
not being
mentioned here, it is late today...).
Major question, as always: who is able to write a proposal and to organize
this process? Are there volunteers?
All the best,
Helmut
------------------------------------------------------------------------
Dr. Helmut Z. Baumert
*IAMARIS e.V. - Angewandte Wasserforschung *
Gesch�ftsf�hrung
Bei den M�hren 69 A
20457 Hamburg
Fon 040 3690 5195
Fax 040 3690 5196
http://export.arxiv.org/api/query?search_query=all:baumert+AND+helmut
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