Baroclinic vs. barotropic mode - Revision history

Yjzhang: /* Mode descriptions */

2012-08-30T01:14:05Z

‎Mode descriptions

Yjzhang at 16:26, 29 August 2012

2012-08-29T16:26:00Z

Eli at 17:08, 27 August 2012

2012-08-27T17:08:32Z

Eli: Created page with " == Mode descriptions == Some description of the Baroclinic and Barotropic equations is given in the SELFE paper. A little elaboration will convey how these are implemented an..."

2012-08-27T17:07:29Z

Created page with " == Mode descriptions == Some description of the Baroclinic and Barotropic equations is given in the SELFE paper. A little elaboration will convey how these are implemented an..."

New page

== Mode descriptions ==
Some description of the Baroclinic and Barotropic equations is given in the SELFE paper. A little elaboration will convey how these are implemented and used in practice.

The Baroclinic and Barotropic modes are toggled in the model by means of the parameter ***. They differ in that in Baroclinic mode, the contribution of salinity-induced density differences is included in the momentum equations. In contrast, in Barotropic mode salt and temperature are (at most) considered passive tracers.

In barotropic mode:
* You can choose whether to calculate salt and temperature transport by toggling the ''itracer'' parameter in the ''param.in'' file.
* This choice affects performance (see below) and also data requirements for salt and temperature. The model (****is/isn't smart) about ...
* The contribution of density to horizontal pressure gradients is dropped.
* The turbulence closure is still calculated in 3D, but the supression of turbulence due to stratification is not included.

== Performance considerations ==
Barotropic mode calculation can be a lot faster than Baroclinic. A key speedup is achieved by setting ''itracer=0'' and neglecting salt and temperature entirely, which is particularly common in the case that subcycling of transport is a performance limiter.

== Boundary and well-posedness issues ==

== Sequential barotropic-baroclinic analysis ==
One common usage pattern is to use a sequence of barotropic-baroclinic model runs. The barotropic simulation is used in a preliminary sweep in order to calculate 3D boundary conditions for the subsequent baroclinic analysis. Typically this is done with transport off, maximizing speed for the barotropic step.

@@ Line 3: / Line 3: @@
 Some description of the Baroclinic and Barotropic equations is given in the SELFE paper. A little elaboration will convey how these are implemented and used in practice.
-The baroclinic and barotropic modes are toggled in the model by means of the parameter ***. They differ in that in Baroclinic mode, the contribution of salinity-induced density differences is included in the momentum equations. In contrast, in Barotropic mode salt and temperature are (at most) considered passive tracers.
+The baroclinic and barotropic modes are toggled in the model by means of the parameter ''ibcc'' in param.in. They differ in that in Baroclinic mode, the contribution of temperature- and salinity-induced density differences is included in the momentum equations. In contrast, in Barotropic mode salt and temperature are (at most) considered passive tracers.
 In barotropic mode:
-* You can choose whether to calculate salt and temperature transport by toggling the ''itracer'' parameter in the ''param.in'' file.
+* You can choose whether to calculate salt and temperature transport by toggling the ''itransport'' parameter in the ''param.in'' file.
 * This choice affects performance (see below) and also data requirements for salt and temperature. The model (****is/isn't smart) about ...
 * The contribution of density to horizontal pressure gradients is dropped.
@@ Line 12: / Line 12: @@
 == Performance considerations ==
-Barotropic mode calculation can be a lot faster than baroclinic. A key speedup is achieved by setting ''itracer=0'' and neglecting salt and temperature entirely, which is particularly common in the case that subcycling of transport is a performance limiter.
+Barotropic mode calculation can be a lot faster than baroclinic. A key speedup is achieved by setting ''itransport=0'' and neglecting salt and temperature entirely, which is particularly common in the case that subcycling of transport is a performance limiter.