Mediterranean Overflow Water (MOW) Simulation Using a Coupled Multiple-Grid Mediterranean Sea/North Atlantic Ocean Model

A z-level, 4th-order-accurate ocean model is applied in six two-way-coupled grids spanning the Mediterranean Sea and North Atlantic Ocean (MEDiNA). Resolutions vary from 1/4 deg in central North Atlantic to 1/24 deg in Strait of Gibraltar region. This allows the MEDiNA model to efficiently resolve s...

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Bibliographic Details
Main Authors: Dietrich, David E, Tseng, Yu-Heng, Medina, Raul, Piacsek, Steve A, Liste, Maria, Olabarrieta, Maitane, Bowman, Malcolm J, Mehra, Avichal
Format: Report
Language:English
Subjects:
COUPLED MODELS
COUPLING(INTERACTION)
DENSITY
DENSITY CURRENTS
DOME(DYNAMICS OF OVERFLOW MIXING AND ENTRAINMENT)
ENTRAINMENT
GIBRALTAR STRAIT
MEDINA OCEAN MODEL
MEDITERRANEAN SEA
MIXING
MOW(MEDITERRANEAN OVERFLOW WATER)
NORTH ATLANTIC OCEAN
OCEAN CURRENTS
OCEAN MODELS
PE0602435N
Physical and Dynamic Oceanography
REPRINTS
SALINITY
WU73-6631-C6-5
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Summary:A z-level, 4th-order-accurate ocean model is applied in six two-way-coupled grids spanning the Mediterranean Sea and North Atlantic Ocean (MEDiNA). Resolutions vary from 1/4 deg in central North Atlantic to 1/24 deg in Strait of Gibraltar region. This allows the MEDiNA model to efficiently resolve small features (e.g., Strait of Gibraltar) in a multibasin, multiscale model. Such small features affect all scales because of nonlinearity and low dissipation. The grid coupling using one coarse grid overlap is nearly seamless without intergrid sponge layers. No instant convective adjustment or other highly diffusive process is used. The deep water in the 1/8 deg Mediterranean Sea grid is formed by the resolved flows that emulate subgrid-scale processes directly. Downslope migration of Mediterranean Overflow Water (MOW) water involves dense water flowing away from the bottom laterally over bottom stairsteps in the z-level model, thus flowing over less dense underlying water. Without excessively water mass-diluting process, the advection dominates the downs lope migration of thin, dense MOW in the simulation. The model results show realistic MOW migration to the observed equilibrium depth, followed by lateral spreading near that depth. The results are also consistent with the climatology along 43 deg N, where the MOW hugs a steep shelfslope centered at 1 km depth and then spreads westward, with the salinity core (S 35.7) reaching 18 deg W. This study clearly restores z-level models to a competitive status doing density current simulations. Published in Journal of Geophysical Research, v113 nC07027, 2008. The original document contains color images. All DTIC reproductions will be in black and white.