Changes between Version 90 and Version 91 of doc/app/initialization_parameters

Timestamp:

Sep 15, 2010 11:30:33 AM (14 years ago)

Author:

kanani

Comment:

--

doc/app/initialization_parameters

@@ -917 +917 @@
 |----------------
 {{{#!td style="vertical-align:top"
-[=#<insert_parameter_name> '''<insert_parameter_name>''']
-}}}
-{{{#!td style="vertical-align:top"
-<insert type>
-}}}
-{{{#!td style="vertical-align:top"
-<insert value>
-}}}
-{{{#!td
-<insert explanation>
-}}}
-|----------------
-{{{#!td style="vertical-align:top"
-[=#<insert_parameter_name> '''<insert_parameter_name>''']
-}}}
-{{{#!td style="vertical-align:top"
-<insert type>
-}}}
-{{{#!td style="vertical-align:top"
-<insert value>
-}}}
-{{{#!td
-<insert explanation>
+[=#rayleigh_damping_factor '''rayleigh_damping_factor''']
+}}}
+{{{#!td style="vertical-align:top"
+R
+}}}
+{{{#!td style="vertical-align:top"
+0.0 or 0.01
+}}}
+{{{#!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.\\\\
+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.
+}}}
+|----------------
+{{{#!td style="vertical-align:top"
+[=#rayleigh_damping_height '''rayleigh_damping_height''']
+}}}
+{{{#!td style="vertical-align:top"
+R
+}}}
+{{{#!td style="vertical-align:top"
+2/3 *\\
+zu(nz)\\\
+(ocean: 2/3*\\
+zu(0))
+}}}
+{{{#!td
+Height above (ocean: below) which the Rayleigh damping starts (in m).\\\\
+With Rayleigh damping switched on (see [#rayleigh_damping_factor rayleigh_damping_factor]), this parameter determines the range where damping is applied. By default, Rayleigh damping will be applied in the upper (ocean: lower) third of the model domain.
 }}}
 |----------------