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MOM4: the Ocean Model for CFSRR. Jiande Wang Xingren Wu David Behringer and Hua-Lu Pan. Outline. Main feature of MOM4 What we did and doing on MOM4 Preliminary results from coupled run. What’s MOM4. The Modular Ocean Model (MOM4) is a numerical representation of the ocean’s
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MOM4: the Ocean Model for CFSRR Jiande Wang Xingren Wu David Behringer and Hua-Lu Pan
Outline • Main feature of MOM4 • What we did and doing on MOM4 • Preliminary results from coupled run
What’s MOM4 • The Modular Ocean Model (MOM4) is a numerical representation of the ocean’s hydrostatic primitive equations developed by GFDL. It is designed primarily as a tool for studying the ocean climate system.
Release & Version of MOM4 • Jan, 2004: MOM4p0a • Mar, 2004: MOM4p0b • Aug, 2004: MOM4p0c • Dec, 2004: MOM4cDec10 • Jun, 2005: MOM4d • Final version: MOM4p0 this is what we are using now
Main Feature • Coded in Fortran90, units are KMS • Re-engineered Parallel infrastructure (MPI) • All I/O is handled via NetCDF, will support IEEE format output in the future. • Only contains one cpp-preprocessor option (ifdefs), (MOM3 has 300-400 ifdefs). • Upside: clean up the logic in the separate modules, code more readable, short compiling time. • Downside: increase code maintenance. System structure becomes complicated (~80 directories). • 2D horizontal domain decomposition. No memory windows or slabs. Increase computation efficiency.
Numerical/dynamic characteristics • Generalized orthogonal horizontal coordinator. Support both standard spherical coordinator and “tripolar” grid (no polar filter required, full Arctic Ocean). • Z-coordinator vertically. Only support B-grid currently. • Partical cell for bottom topography • Non-Boussinesq explicit free surface (Greatbatch et al. 2002). • explicit fresh water flux • McDougall et al. (2003) equation of state with in situ density a function of local potential temperature, salinity and hydrostatic pressure. • Various kind of tracer advection schemes. • KPP vertical mixing (Large et al. 1994) • Chlorophyll based shortwave penetration (Morel and Antoine, 1994) • runoff process
SeaWiFS Chlorophyll (Sweeney et al. 2005) Note the large value near coasts and equatorial pacific and Atlantic which are associated with high level of biological activity
Impact of runoff from Amazon on sea surface salinity MOM3 MOM4 Including of runoff process revealed detail structure of salinity near the river mouth
Model configuration Horizontal resolution: (1). 1 degree zonally, 1/3 degree in tropics, gradually increasing meridionally to 1 degree 30N and 30S. (2). 0.5 degree zonally, 1/4 degree in tropics, gradually increasing meridionally to 0.5 degree 30N and 30S Vertical resolution: 40 layers, 10 meters depth in the up 200 meters.
What we did and doing with MOM4 • Simple test (platform compatibility and reproductively) • Ocean only forced by R2 • Ocean+Ice forced by R2 • Ocean data assimilation (Dave Behringer) • Ocean+Ice+GFS: coupled model
Results from coupled run: SST Less than 1 degree of SST bias in most of tropical region
GODAS Depth MOM4 MOM4-GODAS Small temperature bias in equatorial Pacific region
MOM4 OISST
Summary • MOM4 has been tested in EMC climate group as a component for the coupled system with encouraging results.