\chapter{Namelists and parameters}
To set-up a CAT simulation different types of namelists are available. 
A CAT namelist cat{\_}nl to control the numerics and physics of CAT
simulations in general and a simulation namelist sim{\_}nl which specifies 
a list of predefined simulations.\\ 

\noindent
{\bf \Large CAT control: cat{\_}nl} \\
\noindent
We have subdivided the control parameters of CAT into a group of model
numerics and model physics. \\

\noindent
{\bf Model set-up} \\ 
\noindent
\begin{tabular}{|l|r|l|}
 \hline
 parameter & default & options, description and type \\
 \hline
 nx      &   64       & grid points in x-direction (integer) \\
 ny      &   64       & grid points in y-direction (integer) [not active ny = nx] \\
 nl      &   1        & number of layers (integer) [not active]  \\
 nsteps  &   10000    & number of time steps to be integrated (integer) \\
 ngp     &   100      & time steps between output of grid-point  \\
         &            & fields (integer) \\
 nsp     &   100      & time steps between output of spectral  \\
         &            & fields (integer) \\
 ngui    &   1        & 1/0 graphical user interface on/off (integer) \\
 \hline
\end{tabular} 

\vspace{0.5cm}

\noindent
{\bf Physics} \\ 
\noindent
\begin{tabular}{|l|r|l|}
 \hline
 parameter & default & options and description \\
 \hline
 jac{\_}mthd  &  1       & approximation method of Jacobian  \\
              &          & 0 : no Jacobian  \\
              &          & 1 : divergence form \\
 \hline
\end{tabular}

\vspace{0.5cm}

\noindent
{\bf Postprocessing} \\
\noindent
\begin{tabular}{|l|r|l|}
 \hline
 parameter & default & options and description \\
 \hline
 npost        &  0       & 1/0 additional postprocessing on/off \\
 \hline
\end{tabular}

\vspace{0.5cm}
\noindent
{\bf \Large Predefined simulations: sim{\_}nl} \\
With activated predefined     

{\bf Simulations} \\
\noindent
\begin{tabular}{|l|r|l|}
 \hline
 parameter & default & options and description \\
 \hline
 sim          &  \tt{"dec01"} & class of predefined simulations (character array) \\
              &                & \tt{"dec01"} : decaying turbulence \\
              &                & \tt{"for01"} : forced decaying turbulence \\
              &                & \tt{"jet01"} : top-hat jet \\
              &                & \tt{"vor01"} : gaussian elliptical vortex \\
 \hline
\end{tabular}