MOM2 relative to MOM1 There are major architectural differences between MOM2 and MOM1, as well as some important upgrades in the physics and numerics. The following is a brief outline of the changes.
Certain variables have changed names, with an aim towards a more systematic convention.
The latitude ``j'' index has been added to expose all indices of arrays.
A memory window has been introduced which allows flexibility in parallelization as well as for discretizing higher order operators.
Various modules can be exercised alone or as part of a fully configured model.
An integrated DATABASE is provided to more easily prepare data for any the model resolution.
A generalized surface boundary condition interface which handles all surface boundary conditions as if they come from a hierarchy of atmospheric models.
Elliptic equation solvers for the external mode have been re-worked to be more accurate and give speedier convergence .
The vertical velocity fields have been reformulated to prevent numerical separation in the presence of sharp topographic gradients.
All diagnostics have been re-written to be more modular, old ones have been improved, many new ones added (such as reconstructing the surface pressure from the stream function, calculating particle trajectories, time averaged fields, xbt's etc.).
The prognostic surface pressure and implicit free surface methods of Dukowicz and Smith (1993,1994) have been implemented.
The isoneutral diffusion scheme of Griffies et al. (1998) has been implemented.
The eddy advection of Gent and McWilliams (1990) has been implemented, with numerics made consistent with the new isoneutral diffusion formulation.
Options for tracer advection include the traditional centered differences, a fourth order advection scheme taken from Mahlman's stratospheric code (SKYHI), the FCT scheme of Gerdes, Koberle and Willebrand (1991), a third order advection scheme (by Holland) very similar to the Quick scheme of Leonard (1979).
The pressure gradient averaging technique of Brown and Campana (1978).
Neptune effect of Holloway (1992).
Rigid grid rotation; i.e., rotate poles, while keeping the identical lat/lon structure.
Open boundaries of Stevens (1990).
The discretization of vertical mixing of Pacanowski/Philander (1981) has been changed to yield more accurate and stable solutions.
Some restructuring of the memory window logic to allow for a more robust implementation of parallelism and fourth order schemes.
All diagnostics have been given an interface to generate NetCDF formatted output.