Do We Require Adiabatic Dissipation Schemes in Eddy-Resolving Ocean Models?

Abstract Use of horizontal diffusion of temperature and salinity in numerical ocean models causes spurious diapycnal transfers—the “Veronis effect”—leading to erosion of the thermocline and reduced poleward heat transports. The authors derive a relation between these diapycnal transfers and the dissipation of vorticity gradients. An increase in model resolution does not significantly reduce the diapycnal transfers since vorticity gradients cascade to smaller scales and must ultimately be dissipated to maintain numerical stability. This is confirmed in an idealized primitive equation ocean model at a variety of resolutions between 1° and 1/8°. Thus, the authors conclude that adiabatic dissipation schemes are required, even in eddy-resolving ocean models. The authors propose and implement a new biharmonic form of the Gent and McWilliams scheme, which adiabatically dissipates at the grid scale while preserving larger-scale features.

[1]  M. Spall,et al.  Specification of eddy transfer coefficients in coarse resolution ocean circulation models , 1997 .

[2]  John F. B. Mitchell,et al.  The second Hadley Centre coupled ocean-atmosphere GCM: model description, spinup and validation , 1997 .

[3]  Syukuro Manabe,et al.  Transient responses of a coupled ocean-atmosphere model to gradual changes of atmospheric CO2 , 1991 .

[4]  Jay P. Boris,et al.  Flux-corrected transport. I. SHASTA, a fluid transport algorithm that works , 1973 .

[5]  C. Garrett,et al.  On a Recent Parameterization of Mesoscale Eddies , 1996 .

[6]  Gokhan Danabasoglu,et al.  Sensitivity of the global ocean circulation to parameterizations of mesoscale tracer transports , 1995 .

[7]  GCM studies of intermediate and deep waters in the Mediterranean , 1998 .

[8]  Andrew J. Watson,et al.  Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment , 1993, Nature.

[9]  G. Parrilla,et al.  Decadal changes in water mass characteristics at 24°N in the subtropical north Atlantic Ocean , 1996 .

[10]  G. Danabasoglu,et al.  The Role of Mesoscale Tracer Transports in the Global Ocean Circulation , 1994, Science.

[11]  K. Bryan.  A Numerical Method for the Study of the Circulation of the World Ocean , 1997 .

[12]  P. Gent,et al.  Isopycnal mixing in ocean circulation models , 1990 .

[13]  J. Thuburn.  Dissipation and Cascades to Small Scales in Numerical Models Using a Shape-Preserving Advection Scheme , 1995 .

[14]  Frank O. Bryan,et al.  An Overlooked Problem in Model Simulations of the Thermohaline Circulation and Heat Transport in the Atlantic Ocean , 1995 .

[15]  Gösta Walin,et al.  On the relation between sea‐surface heat flow and thermal circulation in the ocean , 1982 .

[16]  G. Parrilla,et al.  Rising temperatures in the subtropical North Atlantic Ocean over the past 35 years , 1994, Nature.

[17]  Stephen M. Griffies,et al.  The Gent–McWilliams Skew Flux , 1998 .

[18]  John K. Dukowicz,et al.  Isoneutral Diffusion in a z-Coordinate Ocean Model , 1998 .