Changeset 109 for trunk/documentation


Ignore:
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:
1 added
1 copied

Legend:

Unmodified
Added
Removed
  • TabularUnified trunk/documentation/disvert.tex

    r108 r109  
    3333\vspace{1cm}
    3434\Large
    35 The upper boundary sponge layer
     35The vertical discretization
    3636}
    3737
     
    4343\end{center}
    4444
    45 %\section{Theoretical aspects}
     45
     46\section{Theoretical aspects}
     47
     48The position of the layers:
     49\begin{itemize}
     50\item pressure limit between two layers,
     51\item pressure within the layers
     52\end{itemize}
     53
     54The Exner function: definition.
     55It corresponds to the pressure levels within the layers.
     56Used for the computation of the potential temperature.
     57For the Earth, we use a specific scheme that computes these positions so that
     58it maintains a condition of proportionality between total,
     59internal and potential energy (cf. a note from F. Hourdin).
    4660
    4761\section{Pratical aspects in the code}
    4862
    49 The sponge layer is applied at the upper boundary when the \textsf{ok\_strato}
    50 flag is set to {\em True} in \textsf{gcm.def}
    51 (this parameter also controls the application of a second step in the
    52 horizontal dissipation).
     63\begin{itemize}
     64\item \textsf{disvert\_[no]terre.F[90]}:
     65position of the interface pressure levels from an input file
     66(several possibilities).
     67Definition of ap, bp and presnivs.
     68In the planetary version, definition of aps and bps.
    5369
    54 The tendencies for the upper boundary sponge layer are computed separately in
    55 the \textsf{top\_bound.F} routine, called from \textsf{leapfrog.F}.
    56 These tendencies are \textsf{dutop}, \textsf{dvtop} and \textsf{dhtop}, in
    57 unit/s.
     70This is done only once, called at the beginning from \textsf{iniconst.F}.
    5871
    59 Three parameters may be adjusted in the \textsf{gcm.def} file:
    60 \begin{itemize}
    61 \item \textsf{iflag\_top\_bound}: selects the affected layers.
    62   \begin{itemize}
    63   \item 1: only the top 4 layers are affected. In this case, the damping rate
    64   is divided by 2 in the second layer, 4 in the third and 8 in the fourth.
    65   \item 2: layers with pressure lower than 100 times the top pressure.
    66   In this case, the damping rate depends linearly on the pressure.
    67   \end{itemize}
    68 \item \textsf{mode\_top\_bound}: selects how the fields are affected.
    69   \begin{itemize}
    70   \item 0: No sponge layer is applied.
    71   \item 1: Zonal and meridional winds are damped to zero.
    72   \item 2: Zonal and meridional winds are damped to their zonally averaged value.
    73   \item 3: Temperature, zonal and meridional winds are damped to their zonally
    74   averaged value.
    75   \end{itemize}
    76 \item \textsf{tau\_top\_bound}: damping rate (in /s) in the top layer.
     72\item Interface pressures:
     73computed in \textsf{caldyn0.F, caldyn.F, integrd.F, leapfrog.F}
     74through the \textsf{pression.F} routine.
     75
     76\item Exner function (and therefore pressure within the layers):
     77computed at three different places in \textsf{leapfrog.F} through the
     78\textsf{exner\_[hyb/milieu].F} routine.
     79For the Earth, we use \textsf{exner\_hyb.F}, that computes the positions in a
     80specific way to maintain a condition of proportionality between total,
     81internal and potential energy (cf. a note from F. Hourdin).
     82For other planets, we use \textsf{exner\_milieu.F}, that computes the positions
     83of these pressure levels exactly in the middle of each layer.
     84Though this fails to maintain the previous condition, there is no evidence of
     85any significant influence on the results, and it makes it a lot easier to
     86define correctly the level positions with the input file.
    7787\end{itemize}
    7888
Note: See TracChangeset for help on using the changeset viewer.