Changeset 109 for trunk/documentation

Timestamp:

Apr 14, 2011, 11:47:04 AM (14 years ago)

Author:

slebonnois

Message:

SLebonnois: discretisation verticale: cohabitation entre
la methode Terre et les autres.

Location:

trunk/documentation

Files:

• disvert.pdf (added)
• disvert.tex (copied) (copied from trunk/documentation/top_bound.tex) (2 diffs)

trunk/documentation/disvert.tex ¶

@@ -33 +33 @@
 \vspace{1cm}
 \Large
-The upper boundary sponge layer
+The vertical discretization
 }
 
@@ -43 +43 @@
 \end{center}
 
-%\section{Theoretical aspects}
+
+\section{Theoretical aspects}
+
+The position of the layers: 
+\begin{itemize}
+\item pressure limit between two layers, 
+\item pressure within the layers
+\end{itemize}
+
+The Exner function: definition. 
+It corresponds to the pressure levels within the layers.
+Used for the computation of the potential temperature.
+For the Earth, we use a specific scheme that computes these positions so that 
+it maintains a condition of proportionality between total,
+internal and potential energy (cf. a note from F. Hourdin). 
 
 \section{Pratical aspects in the code}
 
-The sponge layer is applied at the upper boundary when the \textsf{ok\_strato}
-flag is set to {\em True} in \textsf{gcm.def} 
-(this parameter also controls the application of a second step in the 
-horizontal dissipation).
+\begin{itemize}
+\item \textsf{disvert\_[no]terre.F[90]}: 
+position of the interface pressure levels from an input file
+(several possibilities). 
+Definition of ap, bp and presnivs.
+In the planetary version, definition of aps and bps.
 
-The tendencies for the upper boundary sponge layer are computed separately in
-the \textsf{top\_bound.F} routine, called from \textsf{leapfrog.F}. 
-These tendencies are \textsf{dutop}, \textsf{dvtop} and \textsf{dhtop}, in
-unit/s. 
+This is done only once, called at the beginning from \textsf{iniconst.F}.
 
-Three parameters may be adjusted in the \textsf{gcm.def} file: 
-\begin{itemize}
-\item \textsf{iflag\_top\_bound}: selects the affected layers. 
-  \begin{itemize}
-  \item 1: only the top 4 layers are affected. In this case, the damping rate 
-  is divided by 2 in the second layer, 4 in the third and 8 in the fourth. 
-  \item 2: layers with pressure lower than 100 times the top pressure. 
-  In this case, the damping rate depends linearly on the pressure.
-  \end{itemize}
-\item \textsf{mode\_top\_bound}: selects how the fields are affected.
-  \begin{itemize}
-  \item 0: No sponge layer is applied.
-  \item 1: Zonal and meridional winds are damped to zero.
-  \item 2: Zonal and meridional winds are damped to their zonally averaged value.
-  \item 3: Temperature, zonal and meridional winds are damped to their zonally 
-  averaged value.
-  \end{itemize}
-\item \textsf{tau\_top\_bound}: damping rate (in /s) in the top layer.
+\item Interface pressures: 
+computed in \textsf{caldyn0.F, caldyn.F, integrd.F, leapfrog.F}
+through the \textsf{pression.F} routine.
+
+\item Exner function (and therefore pressure within the layers): 
+computed at three different places in \textsf{leapfrog.F} through the 
+\textsf{exner\_[hyb/milieu].F} routine. 
+For the Earth, we use \textsf{exner\_hyb.F}, that computes the positions in a
+specific way to maintain a condition of proportionality between total,
+internal and potential energy (cf. a note from F. Hourdin). 
+For other planets, we use \textsf{exner\_milieu.F}, that computes the positions
+of these pressure levels exactly in the middle of each layer. 
+Though this fails to maintain the previous condition, there is no evidence of 
+any significant influence on the results, and it makes it a lot easier to 
+define correctly the level positions with the input file.
 \end{itemize}