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\section{Example: Barotropic Ocean Gyre In Cartesian Coordinates} |
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\label{sect:eg-baro} |
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\bodytext{bgcolor="#FFFFFFFF"} |
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%\begin{center} |
%\begin{center} |
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%{\large May 2001} |
%{\large May 2001} |
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%\end{center} |
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This is the first in a series of sections describing |
This is the first in a series of tutorials describing |
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example MITgcm numerical experiments. The example experiments |
example MITgcm numerical experiments. The example experiments |
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include both straightforward examples of idealized geophysical |
include both straightforward examples of idealized geophysical |
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fluid simulations and more involved cases encompassing |
fluid simulations and more involved cases encompassing |
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the experimental configuration and detailed information on how to |
the experimental configuration and detailed information on how to |
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configure the MITgcm code and input files for each experiment. |
configure the MITgcm code and input files for each experiment. |
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\subsection{Experiment Overview} |
\section{Barotropic Ocean Gyre In Cartesian Coordinates} |
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\label{sect:eg-baro} |
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This example experiment demonstrates using the MITgcm to simulate |
This example experiment demonstrates using the MITgcm to simulate |
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a Barotropic, wind-forced, ocean gyre circulation. The experiment |
a Barotropic, wind-forced, ocean gyre circulation. The experiment |
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equation |
equation |
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\begin{equation} |
\begin{equation} |
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\label{EQ:fcori} |
\label{EQ:eg-baro-fcori} |
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f(y) = f_{0}+\beta y |
f(y) = f_{0}+\beta y |
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\end{equation} |
\end{equation} |
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\noindent where $y$ is the distance along the ``north-south'' axis of the |
\noindent where $y$ is the distance along the ``north-south'' axis of the |
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simulated domain. For this experiment $f_{0}$ is set to $10^{-4}s^{-1}$ in |
simulated domain. For this experiment $f_{0}$ is set to $10^{-4}s^{-1}$ in |
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(\ref{EQ:fcori}) and $\beta = 10^{-11}s^{-1}m^{-1}$. |
(\ref{EQ:eg-baro-fcori}) and $\beta = 10^{-11}s^{-1}m^{-1}$. |
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\\ |
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The sinusoidal wind-stress variations are defined according to |
The sinusoidal wind-stress variations are defined according to |
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\begin{equation} |
\begin{equation} |
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\label{EQ:taux} |
\label{EQ:eg-baro-taux} |
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\tau_x(y) = \tau_{0}\sin(\pi \frac{y}{L_y}) |
\tau_x(y) = \tau_{0}\sin(\pi \frac{y}{L_y}) |
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\end{equation} |
\end{equation} |
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$\tau_0$ is set to $0.1N m^{-2}$. |
$\tau_0$ is set to $0.1N m^{-2}$. |
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Figure \ref{FIG:simulation_config} |
Figure \ref{FIG:eg-baro-simulation_config} |
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summarizes the configuration simulated. |
summarizes the configuration simulated. |
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\begin{figure} |
\begin{figure} |
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\caption{Schematic of simulation domain and wind-stress forcing function |
\caption{Schematic of simulation domain and wind-stress forcing function |
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for barotropic gyre numerical experiment. The domain is enclosed bu solid |
for barotropic gyre numerical experiment. The domain is enclosed bu solid |
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walls at $x=$~0,1200km and at $y=$~0,1200km.} |
walls at $x=$~0,1200km and at $y=$~0,1200km.} |
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\label{FIG:simulation_config} |
\label{FIG:eg-baro-simulation_config} |
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\end{figure} |
\end{figure} |
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\subsection{Equations Solved} |
\subsection{Equations Solved} |
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configuration as follows |
configuration as follows |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:model_equations} |
\label{EQ:eg-baro-model_equations} |
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\frac{Du}{Dt} - fv + |
\frac{Du}{Dt} - fv + |
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g\frac{\partial \eta}{\partial x} - |
g\frac{\partial \eta}{\partial x} - |
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A_{h}\nabla_{h}^2u |
A_{h}\nabla_{h}^2u |
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This value is chosen to yield a Munk layer width \cite{adcroft:95}, |
This value is chosen to yield a Munk layer width \cite{adcroft:95}, |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:munk_layer} |
\label{EQ:eg-baro-munk_layer} |
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M_{w} = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}} |
M_{w} = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}} |
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\end{eqnarray} |
\end{eqnarray} |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:laplacian_stability} |
\label{EQ:eg-baro-laplacian_stability} |
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S_{l} = 4 \frac{A_{h} \delta t}{{\Delta x}^2} |
S_{l} = 4 \frac{A_{h} \delta t}{{\Delta x}^2} |
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\end{eqnarray} |
\end{eqnarray} |
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\cite{adcroft:95} |
\cite{adcroft:95} |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:inertial_stability} |
\label{EQ:eg-baro-inertial_stability} |
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S_{i} = f^{2} {\delta t}^2 |
S_{i} = f^{2} {\delta t}^2 |
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\end{eqnarray} |
\end{eqnarray} |
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horizontal flow speed of $ | \vec{u} | = 2 ms^{-1}$ |
horizontal flow speed of $ | \vec{u} | = 2 ms^{-1}$ |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:cfl_stability} |
\label{EQ:eg-baro-cfl_stability} |
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S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} |
S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} |
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\end{eqnarray} |
\end{eqnarray} |
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of 0.5 and limits $\delta t$ to $1200s$. |
of 0.5 and limits $\delta t$ to $1200s$. |
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\subsection{Code Configuration} |
\subsection{Code Configuration} |
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\label{SEC:code_config} |
\label{SEC:eg-baro-code_config} |
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The model configuration for this experiment resides under the |
The model configuration for this experiment resides under the |
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directory {\it verification/exp0/}. The experiment files |
directory {\it verification/exp0/}. The experiment files |