Dear GOTM community,

first of all, the GOTM team is happy to present a new member, Georg Umgiesser from ISDGM in Venice, Italy. Georg did and will do useful work in the area of linking GOTM to 3D models, structure of the model etc...

The GOTM team is furthermore glad to announce the release of GOTM v. 1.2.0, which contains two basically new features:

  1.  a separation of the mean flow and the turbulence part in order to allow for easy inclusion of GOTM turbulence closure schemes into three-dimensional models and
  2. a number of new stability functions.
For the details, see below.

This new GOTM version needs separate  namelists for general settings and for turbulence specifications,
such that the old namelists have to be replaced. The existing GOTM scenarios (test cases with forcing and
validation data) will be equipped with these new namelists. For those who would like to continue working
with the old version GOTM v. 1.1.3, the old namelist can still be downloaded from the GOTM web site.

GOTM v. 1.2.0 is still written in FORTRAN77, since many three-dimensional models are not yet on
FORTRAN90 standard. Before end of this month, we however intend to release GOTM v. 2.0.0 which will
be written in FORTRAN90. It will include all innovations of GOTM v. 1.1.3. Moreover, GOTM v.2.0.0 will have many more innovations and will be accompanied with numerous new test cases. This will in detail be discussed in a further round mail by end of this month.

For those who are confused about our version numbering:

The innovations of GOTM v. 1.2.0 in detail:
  1. Separation of mean flow and turbulence models. GOTM is rewritten such that all turbulence models are called by only one subroutine 'gotmturb' in the main loop. All mean flow properties needed for the forcing of the turbulence part are included in the parameter list of 'gotmturb'. These are shear and buoyancy frequency, layer thicknesses, and surface and bottom friction velocity. There are two include files now, one for general and mean flow settings (const.i) and one for turbulence settings (gotmturb.i). The turbulence subroutines are by means of this completely separated from the rest of GOTM. The turbulence subroutines together with the turbulence common block and a turbulence namelist (for specifying turbulence model settings) may now be incorporated into a three-dimensional ocean model such as MOM (Modular Ocean Model). On the side of the 3D model, an interface to GOTM extracting water column vectors in GOTM format from the 3D model format would have to be created. GOTM would then have to be called at each water column when the 3D model is looping over the horizontal grid. The GOTM team will work on a prototype for such an interface between GOTM and a 3D model. All present or future GOTM users are invited to participate in this effort. Which will be principally more comfortable with the F90 version.  We would like to acknowledge here Encho Demirov (for mailing address, see GOTM user group) for reviving our interest in separating turbulence and mean flow during a visit at IfM Hamburg, Germany. He suggested to make a coupling between GOTM and MOM.
  2. New stability functions. Prof. Vittoro Canuto (for mailing address, see GOTM user group) made a manuscript (submitted to J. Phys. Oceanogr.) about new stability functions available to the GOTM team. These functions prove to allow for mixing even at higher Richardson numbers and therefore solve a problem always associated with differential turbulence closure models: that they predict a mixed layer depth too low and therefore a sea surface temperature too high. Hans Burchard and Karsten Bolding submitted a manuscript to J. Phys. Oceanogr., in which they show how these new stability functions may be properly incorporated into a k-epsilon model. A file of this manuscript in electronic format (ps or pdf) may be downloaded from the GOTM web site, see publications. A number of other new, more simple stability functions are implemented as well.
  3. For the k-kL model, the buoyancy parameter E3 may now be read in from the namelist. In a short manuscript, Hans Burchard shows how this parameter can be properly estimated, see the electronic file for download in 'publications'.
  4. The turbulence closure model by Bougeault & Andre (1986) has been completely rewritten. Some bugs were removed. It does now not any more require extra evaluation of the equation of state. We would like to acknowledge Henrique Coelho (for mailing address, see GOTM user group) for assistance in improving the code. This subroutine is still in a preliminary state, for comments, please contact Manuel Ruiz Villarreal.
  5. A small bug in the flux boundary condition for the dissipation rate epsilon had already been removed for version 1.1.3. It was Patrick Luyten  who found it and won a beer ...
Any questions/comments/suggestions are warmly welcome.

Finally, we would like to inform you about the possibility to make your turbulence related and  freshly submitted manuscripts available to the GOTM public by sending them in electronic form (ps and pdf formats preferred) to our webmaster Pierre-Philippe Mathieu. He would place your submitted manuscript in the Publications section. Since, for some technical reasons, we do not yet provide an automatic mailing list, you may send an accompanying text to Hans Burchard, which would then be sent to the complete GOTM mailing list. A copy of that text will as well be sent for further dissemination to Ilse Hamann, the administrator of the CARTUM project.

Best modelling wishes for the new year,

The GOTM Team.

Hans Burchard
Karsten Bolding
Manuel Ruiz Villarreal
Pierre-Philippe Mathieu
Georg Umgiesser