the GOTM Team is
happy to inform you about the release of GOTM v. 2.2.0, which has a number
of new features compared to older versions. GOTM v. 2.2.0 is an update
of GOTM v. 2.0.1 (written in FORTRAN90) which you could up to now download
from our web site at http://www.gotm.net.
The FORTRAN77 version 1.2.2 will not be further updated but still be available
for download from the web site, in order to allow for inclusion of its
turbulence module in three-dimensional models written in F77. We apologise
for this long mail. For those who intend to read it later or who prefer
to read it through the web, see above.
It should be noted that this new code is not backward compatible with
the old test cases from GOTM v2.0.? because the namelists are extensively
extended now. Thus, besides the code, test cases have to be downloaded
as well. The new features in GOTM v. 2.2.0 are listed here briefly:
1. Surface wave breaking parameterisation for k-epsilon model
(Craig & Banner 1994, Craig 1996). The underlying physical ideas are
presented and discussed in a manuscript by Hans Burchard (Simulating the
wave-enhanced layer under breaking surface waves with two-equation turbulence
models, submitted to J. Phys. Oceanogr.), which can be downloaded
from the Publications section on the GOTM web site). Basically, the ideas
of Craig 1996 are modified
for the epsilon equation in a straightforward manner. The remaining open
question is for the surface roughness, which still needs to be prescribed.
Boris Kagan (St. Petersburg, Russia)
is currently developing a more general model including the prediction of
the surface roughness.
2. Surface roughness from Charnok 1955 formula as adapted to
sea surface roughness. This is the simple alternative for better surface
roughness models to be presented. We now many researchers who dislike the
Charnok formula, and they are right. However, they do not have better ideas
... Should we be wrong, please send us these better alternatives for inclusion
3. Vertical advection (long internal waves) for moving the pycnocline
up and down. This simple parameterisation moves the whole water column
with one vertical velocity. The effect is that the distance of the pycnocline
from the surface or bed will be corrected e.g. according to observations.
We had to include this process for simulating the dynamics in the northern
North Sea, a test case which will soon put onto the web for you.
4. Online calculation of surface fluxes by using standard bulk
formulae and simulated SST (Kondo 1975). Of major importance, but
not directly related to the turbulence model itself, is the forcing at
the sea surface. Until now files with momentum- and heat-fluxes had to
be provided. In many cases this is an OK solution - but in a project we
had a situation where we did not have access to sea surface temperature
but only variables from a
meteorological model - might often be the case. We therefore now have
implemented a scheme where we use the model calculated sea surface temperature
together with information on wind, relative humidity, air temperature to
calculate the fluxes during the model integration. The method is included
in the present release (set 'calc_fluxes' to .true. in airsea.inp + provide
a file with meteorological variables) and is working - but is still a bit
rough on the edges. Those who are interested can contact Karsten
Bolding for further info. The advantage is that 'gotm' now can be set
up for virtually any place in the world - the necessary meteorological
variables can be obtained from many sources - either from the web or from
meteorological institutes/agencies. In the near future a test case using
the above method will be available from www.gotm.net - a one year simulation
from the North Sea.
Releated to the above, Luis Montenegro
together with Vittorio Canuto
at NASA/GISS, is working on implementing fresh water fluxes at the sea
surface - but not only that, they are also working on different diffusivities
for salt and heat - allowing people to use 'gotm' for investigating the
importance of differential mixing. They have access to some very good field
data for verification purposes. Hopefully in the next stable release and
as a downloadable example.
1. Conservative calculation of shear production inside meanflow
module, see the unpublished set of transparencies by Hans
Burchard (Energy conserving discretisation of turbulent shear production)
to be downloaded
from the Publication web page. The basic idea in one sentence: All kinetic
energy which is extracted from the momentum equations by vertical mixing
is converted to turbulent kinetic energy: In reality and in the physical
equations. In straightforward discretisations this is not the case, which
might lead to numerical instabilities. With this new discretisation, this
conservation law is numerically retained. A small peer-reviewed publication
1. Additional NetCDF
model output of shear and buoyancy production, and sigma_t instead
of buoyancy. This is very helpful for investigating GOTM model results.
As a quick and easy graphical platform for viewing results in NetCDF format,
we recommend the use of ‘ncview’.
2. Reading in ADCP data from a file. ADCP observations
are more and more integral part of field campaigns in estuaries shelf seas
and the open ocean. GOTM has now a facility for reading these profile data
for the u and the v component in. So far, it is used for initial conditions
for validation only, but we think about extending it in order to use it
as forcing as well.
New Server for GOTM:
Finally, we managed to find a company who is willing to host gotm.net
on very attractive conditions - anonymous ftp, shell accounts, unlimited
pop-accounts, mailing lists etc. ... and it’s free ! We would here like
to take the opportunity to thank the team at 'tkw-websolutions'
and especially Michael Legart
for the support. Since we now have a place in cyber-space we almost can
call our own we have introduced the following:
1: www.gotm.net is now physically on a server directly on a very
fast connection - no forwarding - therefore if you experience slow downloads
it's not because of gotm.net :-).
2: we have made two mailing lists - firstname.lastname@example.org
and email@example.com. In the future
please use these lists for general questions that might be of relevance
to a broader audience - we also encourage people on the list to actively
participate in answering questions - therefore always reply with a cc to
the list. We have moved all people from the old mailing list to firstname.lastname@example.org.
email@example.com is much more focussed
on the day to day development of gotm - and therefore of greater interest
to people who do actively participate in the development of gotm. It's
not a restricted list though - so if you want to be on the list - please
mail to firstname.lastname@example.org.
In the future we might take advantage of some of the more advanced
features our new 'cyber home' offers e.g. use of data bases, interactive
model runs etc.
Updated web pages:
By looking at our web page at http://www.gotm.net,
you will see that the design is clearer now and made more consistent. Since
the complexity of GOTM is growing and the applications are more diverse,
we try to make it easier and more comfortable to understand and apply GOTM.
Any questions regarding the web pages will be answered by our web master,
In order to increase the communication within the GOTM user community,
we have reactivated the FAQ section and the guest book:
FAQ (Frequently Asked
and Answered Questions) section: Here we have put so far some questions
which we feel are typical. We update this section regularly now. If you
have such questions, please look first into the FAQ section and if you
do not find your question there, please report it to us. The most frequent
question is actually: Why does GOTM not compile and run on my computer
book: We have reanimated the automatic guest book now. We receive so
many positive comments about GOTM that we would like you all to enjoy them.
Since the guest book is much more anonymous than sending personal emails,
we would also expect some negative comments. So please, send your general
comments on GOTM to our guest book.
After a long discussion among the GOTM Team, we think that we have now
found the ultimate graphical system for displaying GOTM results in an easy
and clear way. FERRET
is an interactive computer visualisation and analysis environment designed
to meet the needs of oceanographers and meteorologists analysing large
and complex gridded data sets.
It's main advantages for GOTM compared to other software packages
- Free, runs on PC/Unix.
- Easy NetCDF reading/writing
- Makes time plot, contour, fill, + control of all options
- Handles curvilinear coordinates (moving free surface, sigma
- Well documented (users
- Can be learned in 10mins thanks to demo type "go tutorial"
in Ferret to check its potential.
- Has a scripting language.
- Enables operations line Max/Min, time/space Average, computation
of the depth of the mixed layer, equation of state....
- Has some internal climatological data (Etopo, Levitus observations
- Benefits from Web Ferret (useful for visualising results via
Some Ferret scripts to visualise GOTM results will be provided in the
near future ...
GOTM is growing:
We should finally mention that the GOTM community is steadily growing.
The user group consists today of more than 80 scientists around the
World. Since the first release of GOTM in May 1999, we had about 4000 visits
to our home page from colleagues from over 50 countries World Wide. For
a general statistics since July 1999, please click here,
for extensive statistics on the new server, have a look here.
During the last few months we really feel that 'gotm' has gained momentum
and we get encouraging mails from most of the World – to continue this
positive development we emphasise once again - we need input on all levels!!!!
GOTM is on the way to be a widely accepted community model. It depends
on your support, where the road is going.