Many people have been giving important impulses to the development of GOTM. The first lines of the first PASCAL code have been programmed in late 1992 by the first author of this report as part of a Ph.D. project at the Institut für Meereskunde of the Universität Hamburg, Germany, under the supervision of Jürgen Sündermann and Helmut Baumert. This was the the basis for a one-dimensional water column model for simulating the so-called FLEX'76 data (see Burchard and Baumert [1995]), a two-dimensional channel model (Burchard and Baumert [1998]) and a three-dimensional shallow water model (Burchard [1995]). Further substantial advice for these modelling activities came also from Eckard Kleine (Bundesamt für Seeschiffahrt und Hydrographie, Hamburg, Germany) who together with Helmut Baumert had a long time experience in turbulence modelling (see e.g. Baumert et al. [1989a, 1989b] and Baumert and Radach [1992]).
A strong motivation for extending the model code (which at that stage
only included the k-e model) came in 1995 from
George Mellor (Princeton University, New Jersey) who provoked with the
statement that he never saw a k-e model (in
contrast to the Mellor-Yamada model) reproducing the Monin-Obukhov stability
theory. In an effort together with Ole Petersen (International Centre of
Computational Hydrodynamics, Horsholm, Denmark) the equivalence of the
k-e and the Mellor-Yamada models under certain
circumstances and thus the successful reproduction of the Monin-Obukhov
stability theory could be demonstrated (Burchard et al. [1998], Burchard
and Petersen [1999]). Stability problems occurred when the water column
model (now already with a switch for choosing either the k-e
or the Mellor-Yamada model) was transferred to FORTRAN in late 1996. It
was Boris Kagan (Shirshov Institute of Oceanology, St. Petersburg, Russia)
who insisted that
oscillations in the turbulent macro length scale under very small stable
stratification are numerical artifacts and therefore unacceptable. The
solution to that problem was finally to use double instead of single precision
for the calculations.
In a cooperation with Nadia Pinardi and Sergio Castellari (Istituto per lo Studio delle Metodologie Geofisiche Ambientali, Bologna, Italy) during 1997 and 1998, the experiences of that FORTRAN code were incorporated into a version of the Modular Ocean Model (MOM, Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey) for calculating the general circulation and convective events in the Mediterranean Sea (Castellari et al. [1999]). During the same years, the turbulence model was under strong criticism from Walter Eifler and Adolf Stips (Joint Research Centre, Ispra, Italy) when it was inter-calibrated with in-situ measurements of dissipation rate in two different estuaries. During this effort both, the model and the measurement strategy were significantly improved. However, discrepancies remained and the discussion is still going on (Burchard et al. [1999]).
The idea of GOTM, as it is presented here, was born in spring 1998, when Karsten Bolding (the second author of this report) joined the development. It was a major effort to collect the many different codes (each set up for only one test case), written in different programming languages, stored on different computers and merge them together into one product. In summer 1998, Manuel Ruiz Villarreal (the third author of the first GOTM report) joined us on all levels of GOTM such as internal wave parameterizations, algebraic length scales, documentation, test cases, graphics, etc.
At this stage, the first version of GOTM was copied to the anonymous-ftp server of the Institut für Meereskunde in Hamburg, Germany on May 1, 1999 as GOTM1.0.
Later, Pierre-Philippe Mathieu, JRC Ispra, Italy carried out two major changes which conssiderably ease the use of GOTM. A general tracer routine (yevol.f) has been created for easy addition of further tracer equations such as biological modules. Secondly, a graphical output for the Grid Analysis and Display System (GrADS) was added, which allows for a quick analysis of simulation results. The namelists for the scenarios did not have to be changed. Therefore this new version was called GOTM1.1 and copied to the anonymous-ftp server on July 4, 1999. Such, Pierre-Philippe Mathieu became GOTM author no. 4.