The sponge layer - Historique des versions

Emillour le 9 mai 2022 à 10:10

2022-05-09T10:10:47Z

Emillour le 2 décembre 2021 à 07:53

2021-12-02T07:53:17Z

Emillour : Page créée avec « == in a nutshell == The sponge layer is necessary to damp vertically propagating waves, which would otherwise non-physically be reflected downward from the model top. In p... »

2021-12-01T08:29:23Z

Page créée avec « == in a nutshell == The sponge layer is necessary to damp vertically propagating waves, which would otherwise non-physically be reflected downward from the model top. In p... »

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== in a nutshell ==
The sponge layer is necessary to damp vertically propagating waves, which would otherwise non-physically be reflected downward from the model top.
In practice its application is thus limited to a few of the topmost layers (usually 4), with decreasing impact with decreasing altitudes.
The sponge layer is a relaxation of main variables (winds and/or potential temperature) towards a given value or their zonal mean along a given time scale.

== Sponge layer parameters ==
The parameters controlling the sponge layer are in input file gcm.def
* iflag_top_bound (integer): 0 for no sponge, 1 for a sponge over the last 4 topmost layers, 2 to have a sponge layer extending over topmost layers down to a pressure which is 100 times that of the topmost layer's.
* mode_top_bound (integer): 0 for no relaxation, 1 to relax winds (u,v) to zero, 2 to relax winds (u,v) towards their zonal mean, 3 to relax winds (u,v) and potential temperature towards their zonal mean.
* tau_top_bound (real, Hz): inverse of the relaxation characteristic time scale at the topmost layer; halved at each successive descending layer.

== Application of the sponge ==
The sponge is applied right after dissipation at each dissipation step.

01/12/2021

[[Category:inputs]]

@@ Ligne 11 : / Ligne 11 : @@
 == Application of the sponge ==
-The sponge is applied right after dissipation at each dissipation step.
+The sponge is applied right after dissipation at each dissipation step, but only if the flag '''ok_strato=y'''
-/12/2021
+== Sponge routine ==
 [[Category:inputs]]

@@ Ligne 5 : / Ligne 5 : @@
 == Sponge layer parameters ==
-The parameters controlling the sponge layer are in input file gcm.def
+The parameters controlling the sponge layer are in input file gcm.def (or sometimes in vert_L**.def as they are strongly linked to the vertical grid)
 * iflag_top_bound (integer): 0 for no sponge, 1 for a sponge over the last 4 topmost layers, 2 to have a sponge layer extending over topmost layers down to a pressure which is 100 times that of the topmost layer's.
 * mode_top_bound (integer): 0 for no relaxation, 1 to relax winds (u,v) to zero, 2 to relax winds (u,v) towards their zonal mean, 3 to relax winds (u,v) and potential temperature towards their zonal mean.
-* tau_top_bound (real, Hz): inverse of the relaxation characteristic time scale at the topmost layer; halved at each successive descending layer.
+* tau_top_bound (real, Hz): inverse of the relaxation characteristic time scale at the topmost layer; which is then halved at each successive descending layer.
 == Application of the sponge ==