Dept. of Math.
2011-07-15: BOM 5 alpha4Changes:
2010-12-16: BOM 5 alpha3Changes:
2010-07-16: BOM 5 alpha2Changes:
2010-06-04: BOM 5 alphaAfter many years with no new code released, this is a preliminary version 5 that seems to work well. We decided to integrate all our best code into one single code base, and strip out all case specific code. Noteworthy changes
It is a goal to let all features be turned on or off via the setup file.
There will be more features added on a "needed by project" basis. There is a framework in place for offering user selectable boundary conditions. As of today FRS, Dirichlet, Neuman=0, and periodic is implemented. More will come for realistic forcing, nesting etc.
Scalability for certain choices of open boundary conditions need optimization for use on more than 30-40 processors depending on case size.
A particle tracking module is under development and testing.
One upcoming change is that we will switch from specifying coordinates in the plotting commands with indices and "grid coordinates" into using meters as the unit. this will make config files more generic, and enable very quick changes of experiment resolution.
The code is tested with Portland (pgf90) and the GNU Fortran compiler (gfortran) with MPICH2. Intel ifort does not yet work well with optimization on for all files.
2005-05-06: Internal pressure and rotated gridsA recent work on internal pressure gradient errors in the well known seamount case, has shown that it is possible to reduce the error significantly by computing the gradient as a linear combination of the standard stencil and a stencil rotated 45 degrees with respcect to the model grid.
This new algorithm can easily be implemented in the BOM 4.1 version by following the below steps:
In the file
REAL, DIMENSION(IM,JM) :: DCORNER REAL, DIMENSION(IM,JM,KB) :: DELTAUROT, DELTAVROT
In the BOM source file
... CALL INTERNALROT DELTAUROT = DELTAU DELTAVROT = DELTAV CALL INTERNAL DELTAU = (2.5*DELTAU+DELTAUROT)/3.5 DELTAV = (2.5*DELTAV+DELTAVROT)/3.5 ...
Download the file
at this link
into your BOM source directory, call it
2004-09-01: BOM 4.1 releasedWhile experimenting with non hydrostatic extensions, a typo bug in the predictor part of the time stepping for momentum were found and corrected with this release.
It is very hard to see differences in the results after rerunning experiements and comparing with version 4.0, but this may be case dependant. The 2D solution seems to be non-affected, while e.g. the stratification seems somewhat improved. Generally the bug has lead to a damping of the solution, so it will generally be necessary to increase the viscosity up to levels corresponding to 3.x, likewise reduce the time step, in order to get stable results.
2003-11-18: BOM 4.0 releasedNew predictor corrector time stepping scheme with better stability properties and higher numerical order. The barotropic part of the equations is advanced in time with the leapfrog scheme for the predictor, and the Crank-Nicholson scheme for the corrector. The baroclinic part uses leapfrog for the predictor step and the Adams-Moulton scheme for the corrector step. In some experiments it is now possible to increase the 3d time step with a factor of three relative to version 3.X.
The alternative internal pressures scheme (due to McCalpin) with fourth order discretization along sigma layers has been made a runtime option. By applying the integration by parts rule to the internal pressure term it is possible to do the vertical integral in a more robust way. This scheme has been proven effective to reduce internal pressure error in the infamous Seamount case. It is not, however, clear how beneficial the effects are in more realistic cases.
The numerical kernel of BOM seems to stabilize, so it is not expected that there will be major changes to the core in the future. A non-hydrostatic version of the modesplit routine is under testing, and may be added soon, and depending on funding there may come a separate MPI version of 4.0 next year.
New animations of the contintental shelf on the examplespage
2003-03-03: BOM 3.2 releasedThis release contains a bugfix for the routine ADVECT.f90, which was by accident hardcoded for advecting density only. It can now advect a general field.
Also updated Makefile with flags for Intel Fortran and Pentium4.
2002-09-06: Small bug in 3.0 fixedTwo 3D arrays that should have been globally defined in state.f90, were only declared locally. This is fixed in version 3.0.1.
2002-08-20: BOM 3.0 releasedFinally BOM 3.0 is released, seems to work robustly.
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