Changes between Version 169 and Version 170 of doc/app/initialization_parameters

Timestamp:

Nov 29, 2011 12:26:26 AM (13 years ago)

Author:

raasch

Comment:

--

doc/app/initialization_parameters

@@ -905 +905 @@
 {{{#!td
 Factor for Rayleigh damping.\\\\
-A so-called Rayleigh damping is applied to all prognostic variables if a non-zero value is assigned to '''rayleigh_damping_factor'''. If switched on, variables are forced towards the value of their respective basic states (e.g. the geostrophic wind). The intensity of damping is controlled by the value the '''rayleigh_damping_factor''' is assigned to. The damping starts weakly at a height defined by [#rayleigh_damping_height rayleigh_damping_height] and rises according to a sin^2^-function to its maximum value at the top (ocean: bottom) boundary.\\\\
+A so-called Rayleigh damping is applied to all prognostic variables if a non-zero value is assigned to '''rayleigh_damping_factor'''. If switched on, horizontal velocities, temperature, humidity/scalar (if switched on) and salinity (in case of ocean) are forced towards the value of their respective basic states (defined by the initial profiles of the geostrophic wind, temperature, etc.). In case of large scale subsidence (see [#subs_vertical_gradient subs_vertical_gradient]) the basic state of temperature and humidity is adjusted with respect to the subsidence. Scalar quantities can be excluded from the damping (see [#scalar_rayleigh_damping scalar_rayleigh_damping]). The intensity of damping is controlled by the value the '''rayleigh_damping_factor''' is assigned to. The damping starts weakly at a height defined by [#rayleigh_damping_height rayleigh_damping_height] and rises according to a sin^2^-function to its maximum value at the top (ocean: bottom) boundary.\\\\
 This method effectively damps gravity waves, caused by boundary layer convection, which may spread out vertically in the inversion layer and which are reflected at the top (ocean: bottom) boundary. This particularly happens with the upstream-spline scheme switched on (see [#momentum_advec momentum_advec] or [#scalar_advec scalar_advec]). Therefore, with this scheme the Rayleigh damping is switched on ('''rayleigh_damping_factor''' = ''0.01'') by default. Otherwise it remains switched off.\\\\
 The Rayleigh damping factor must hold the condition ''0.0'' <= '''rayleigh_damping_factor''' <= ''1.0.'' Large values (close to 1.0) can cause numerical instabilities.
@@ -973 +973 @@
 The  upstream-spline scheme is not implemented for humidity and passive scalars (see [#humidity humidity] and [#passive_scalar passive_scalar]) and requires the use of a 2d-domain-decomposition. The last conditions severely restricts code optimization on several machines leading to very long execution times! This scheme is also not allowed for non-cyclic lateral boundary conditions (see [#bc_lr bc_lr] and [#bc_ns bc_ns]).\\\\
 A differing advection scheme can be chosen for the subgrid-scale TKE using parameter [#use_upstream_for_tke use_upstream_for_tke].
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#scalar_rayleigh_damping '''scalar_rayleigh_damping''']
+}}}
+{{{#!td style="vertical-align:top"
+L
+}}}
+{{{#!td style="vertical-align:top"
+.T.
+}}}
+{{{#!td
+Application of Rayleigh damping to scalars.\\\\
+With Rayleigh damping switched on (see [#rayleigh_damping_factor rayleigh_damping_factor]), this parameter determines if the damping is applied also to scalars (temperature, humidity/scalar, salinity) or to the horizontal velocity components only.
 }}}
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