/[MITgcm]/manual/s_phys_pkgs/text/shelfice.tex

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-revision 1.1 by mlosch,
Thu May 14 10:19:12 2009 UTC
+revision 1.5 by mlosch,
Thu Dec  1 11:59:46 2011 UTC
 Line 11 
 Authors: Martin Losch, Jean-Michel Campi
  %----------------------------------------------------------------------
  \subsubsection{Introduction
- \label{sec:pkg:exf:intro}}
+ \label{sec:pkg:shelfice:intro}}
  Package ``shelfice'' provides a thermodynamic model for basal melting
 Line 20 
 underneath floating ice shelves.
  CPP options enable or disable different aspects of the package
  (Section \ref{sec:pkg:shelfice:config}).
  Run-Time options, flags, filenames and field-related dates/times are
- set in \texttt{data.shelfice}
+ set in \code{data.shelfice}
  (Section \ref{sec:pkg:shelfice:runtime}).
  A description of key subroutines is given in Section
  \ref{sec:pkg:shelfice:subroutines}.
  Input fields, units and sign conventions are summarized in
  Section \ref{sec:pkg:shelfice:fields_units}, and available diagnostics
- output is listed in Section \ref{sec:pkg:shelfice:fields_diagnostics}.
+ output is listed in Section \ref{sec:pkg:shelfice:diagnostics}.
  %----------------------------------------------------------------------
 Line 41 
 As with all MITgcm packages, SHELFICE ca
  \begin{itemize}
  %
  \item
- using the \texttt{packages.conf} file by adding \texttt{shelfice} to it,
+ using the \code{packages.conf} file by adding \code{shelfice} to it,
  %
  \item
- or using \texttt{genmake2} adding
+ or using \code{genmake2} adding
- \texttt{-enable=shelfice} or \texttt{-disable=shelfice} switches
+ \code{-enable=shelfice} or \code{-disable=shelfice} switches
  %
  \item
  \textit{required packages and CPP options}: \\
 Line 56 
 schemes, be aware, that non-local parame
  off, e.g.\ for KPP (\ref{sec:pkg:kpp}).
  %
  \end{itemize}
- (see Section \ref{sect:buildingCode}).
+ (see Section \ref{sec:buildingCode}).
  Parts of the SHELFICE code can be enabled or disabled at compile time
  via CPP preprocessor flags. These options are set
- \texttt{SHELFICE\_OPTIONS.h}.
+ \code{SHELFICE\_OPTIONS.h}.
  Table \ref{tab:pkg:shelfice:cpp} summarizes these options.
- \begin{table}[h!]
+ \begin{table}[!ht]
  \centering
    \label{tab:pkg:shelfice:cpp}
    {\footnotesize
 Line 71 
 Table \ref{tab:pkg:shelfice:cpp} summari
        \hline
        \textbf{CPP option}  &  \textbf{Description}  \\
        \hline \hline
-         \texttt{ALLOW\_SHELFICE\_DEBUG} &
+         \code{ALLOW\_SHELFICE\_DEBUG} &
            Include code for enhanged diagnosis \\
-         \texttt{ALLOW\_ISOMIP\_TD} &
+         \code{ALLOW\_ISOMIP\_TD} &
            Include code for simplifed ISOMIP thermodynamics \\
        \hline
      \end{tabular}
    }
-   \caption{Available CPP-flags to be set in \texttt{SHELFICE\_OPTIONS.h}}
+   \caption{Available CPP-flags to be set in \code{SHELFICE\_OPTIONS.h}}
  \end{table}
  %----------------------------------------------------------------------
 Line 87 
 Table \ref{tab:pkg:shelfice:cpp} summari
  \label{sec:pkg:shelfice:runtime}}
  Run-time parameters are set in files
- \texttt{data.pkg} (read in \texttt{packages\_readparms.F}),
+ \code{data.pkg} (read in \code{packages\_readparms.F}),
- and \texttt{data.shelfice} (read in \texttt{shelfice\_readparms.F}).
+ and \code{data.shelfice} (read in \code{shelfice\_readparms.F}).
  \paragraph{Enabling the package}
  ~ \\
  %
  A package is switched on/off at run-time by setting
- (e.g. for SHELFICE) \texttt{useSHELFICE = .TRUE.} in \texttt{data.pkg}.
+ (e.g.\ for SHELFICE) \code{useSHELFICE = .TRUE.} in \code{data.pkg}.
  \paragraph{General flags and parameters}
  ~ \\
  %
  Table~\ref{tab:pkg:shelfice:runtimeparms} lists all run-time parameters.
- \begin{table}[h!]
+ \begin{table}[!ht]
    \caption{Run-time parameters and default values
      \label{tab:pkg:shelfice:runtimeparms}}
    {\footnotesize
 Line 129 
 Table~\ref{tab:pkg:shelfice:runtimeparms
        &  %---ref---
        \\
        SHELFICEtopoFile         & UNSET
-       &   under-ice topography of ice shelfes
+       &   under-ice topography of ice shelves
        &  %---ref---
        \\
        SHELFICElatentHeat       &  334.0E+03
 Line 137 
 Table~\ref{tab:pkg:shelfice:runtimeparms
        &  %---ref---
        \\
        SHELFICEHeatCapacity\_Cp & 2000.0E+00
-       &   latent heat of fusion ($c_{p,I}$)
+       &   specific heat capacity of ice ($c_{p,I}$)
        &  %---ref---
        \\
        rhoShelfIce              &  917.0E+00
 Line 199 
 Table~\ref{tab:pkg:shelfice:runtimeparms
  }
  \end{table}
+ \paragraph{Input fields and units\label{sec:pkg:shelfice:fields_units}}
+ \begin{description}
+ \item[\code{SHEFLICEtopoFile}:] under-ice topography of ice shelves in
+   meters; upwards is positive, that as for the bathymetry files,
+   negative values are required for topography below the sea-level;
+ \item[\code{SHEFLICEloadAnomalyFile}:] pressure load anomaly at the bottom of
+   the ice shelves in pressure units (Pa); this field is absolutely
+   required to avoid large excursions of the free surface during
+   initial adjustment processes; obtained by integrating an approximate
+   density from the surface at $z=0$ down to the bottom of the last
+   fully dry cell within the ice shelf, see
+   Eq.~(\ref{eq:surfacepressure}); however, the file
+   \code{SHEFLICEloadAnomalyFile} must not be $p_{top}$, but
+   $p_{top}-g\sum_{k'=1}^{n-1}\rho_{0}\Delta{z}_{k'}$, with
+   $\rho_{0}=$~\code{rhoConst}, so that in the absenses of a $\rho^{*}$
+   that is different from $\rho_{0}$, the anomaly is zero.
+ \end{description}
  %----------------------------------------------------------------------
  \subsubsection{Description
-Line 228 
 assumed to be floating in isostatic equi
+Line 245 
 assumed to be floating in isostatic equi
  of the water column is the atmospheric pressure $p_{a}$ plus the
  weight of the ice-shelf. It is this weight of the ice-shelf that has
  to be provided as a boundary condition at the top of the water column
- (in run-time parameter \texttt{SHELFICEloadAnomalyFile}).
+ (in run-time parameter \code{SHELFICEloadAnomalyFile}).
  The weight is conveniently computed by integrating a density profile
  $\rho^*$, that is constant in time and corresponds to the sea-water
  replaced by ice, from $z=0$ to a ``reference'' ice-shelf draft at
-Line 277 
 gradient is computed in the center of th
+Line 294 
 gradient is computed in the center of th
  \end{equation}
  where $H(k'-k)=1$ for $k'<k$ and $0$ otherwise.
- Setting \texttt{SHELFICEboundaryLayer=.true.} introduces a simple
+ Setting \code{SHELFICEboundaryLayer=.true.} introduces a simple
  boundary layer that reduces the potential noise problem at the cost of
  increased vertical mixing. For this purpose the water temperature at
  the $k$-th layer abutting ice shelf topography for use in the heat
-Line 390 
 $T_{f}$ which is computed from a linear
+Line 407 
 $T_{f}$ which is computed from a linear
  \begin{equation}
    \label{eq:helmerfreeze}
      T_{f} = (0.0901 - 0.0575\ S_{b})^{\circ}
-     - 7.61 \times 10^{-4}\frac{^{\circ}}{\text{dBar}}\ p_{b}
+     - 7.61 \times 10^{-4}\frac{\text{K}}{\text{dBar}}\ p_{b}
  \end{equation}
  with the salinity $S_{b}$ and the pressure $p_{b}$ (in dBar) in the
  cell at the ice-water interface. From the salt budget, the salt flux
-Line 452 
 equation~(\ref{eq:hellmersaltbalance}) i
+Line 469 
 equation~(\ref{eq:hellmersaltbalance}) i
  formulation it is obvious that melting ($q<0$) leads to a reduction of
  salinity.
- The default value of \texttt{SHELFICEconserve=.false.} removes the
+ The default value of \code{SHELFICEconserve=.false.} removes the
  contribution $q ( X_{b}-X )$ from Eq.~(\ref{eq:jenkinsbc}), making the
  boundary conditions for temperature non-conservative.
-Line 474 
 and the fresh water flux $q$ is computed
+Line 491 
 and the fresh water flux $q$ is computed
    q = - \frac{c_{p} \rho \gamma_T (T - T_{b})}{L}.
  \end{equation}
  In order to use this formulation, set run-time parameter
- \texttt{useISOMIPTD=.true.} in data.shelfice.
+ \code{useISOMIPTD=.true.} in data.shelfice.
  \paragraph{Remark} The shelfice package and experiments demonstrating
  its strenghts and weaknesses are also described in
-Line 487 
 the thermodynamics in the appendix of \c
+Line 504 
 the thermodynamics in the appendix of \c
  \subsubsection{Key subroutines
  \label{sec:pkg:shelfice:subroutines}}
- Top-level routine: \texttt{shelfice\_model.F}
+ Top-level routine: \code{shelfice\_model.F}
  {\footnotesize
  \begin{verbatim}
-Line 505 
 C ...
+Line 522 
 C ...
  C | | |-EXTERNAL_FORCING_T :: Problem specific forcing for temperature.
  C | | |-SHELFICE_FORCING_T :: apply heat fluxes from ice shelf model
  C ...
- C | | |-EXTERNAL_FORCING_S :: Problem specific forcing for temperature.
+ C | | |-EXTERNAL_FORCING_S :: Problem specific forcing for salinity.
  C | | |-SHELFICE_FORCING_S :: apply fresh water fluxes from ice shelf model
  C ...
  C | |-DYNAMICS             :: Momentum equations driver.
-Line 535 
 Diagnostics output is available via the
+Line 552 
 Diagnostics output is available via the
  Available output fields are summarized in
  Table \ref{tab:pkg:shelfice:diagnostics}.
- \begin{table}[h!]
+ \begin{table}[!ht]
  \centering
  \label{tab:pkg:shelfice:diagnostics}
  {\footnotesize
-Line 569 
 Table \ref{tab:pkg:shelfice:diagnostics}
+Line 586 
 Table \ref{tab:pkg:shelfice:diagnostics}
  %%% Local Variables:
  %%% mode: latex
- %%% TeX-master: "../manual"
+ %%% TeX-master: "../../manual"
  %%% End:

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