| 1 | % $Header$ | % $Header$ | 
| 2 | % $Name$ | % $Name$ | 
| 3 |  |  | 
|  | \section{Example: Barotropic Ocean Gyre In Cartesian Coordinates} |  | 
|  | \label{sect:eg-baro} |  | 
|  |  |  | 
| 4 | \bodytext{bgcolor="#FFFFFFFF"} | \bodytext{bgcolor="#FFFFFFFF"} | 
| 5 |  |  | 
| 6 | %\begin{center} | %\begin{center} | 
| 13 | %{\large May 2001} | %{\large May 2001} | 
| 14 | %\end{center} | %\end{center} | 
| 15 |  |  | 
| 16 | This is the first in a series of sections describing | This is the first in a series of tutorials describing | 
| 17 | example MITgcm numerical experiments. The example experiments | example MITgcm numerical experiments. The example experiments | 
| 18 | include both straightforward examples of idealized geophysical | include both straightforward examples of idealized geophysical | 
| 19 | fluid simulations and more involved cases encompassing | fluid simulations and more involved cases encompassing | 
| 25 | the experimental configuration and detailed information on how to | the experimental configuration and detailed information on how to | 
| 26 | configure the MITgcm code and input files for each experiment. | configure the MITgcm code and input files for each experiment. | 
| 27 |  |  | 
| 28 | \subsection{Experiment Overview} | \section{Barotropic Ocean Gyre In Cartesian Coordinates} | 
| 29 |  | \label{sect:eg-baro} | 
| 30 |  |  | 
| 31 |  |  | 
| 32 | This example experiment demonstrates using the MITgcm to simulate | This example experiment demonstrates using the MITgcm to simulate | 
| 33 | a Barotropic, wind-forced, ocean gyre circulation. The experiment | a Barotropic, wind-forced, ocean gyre circulation. The experiment | 
| 44 | equation | equation | 
| 45 |  |  | 
| 46 | \begin{equation} | \begin{equation} | 
| 47 | \label{EQ:fcori} | \label{EQ:eg-baro-fcori} | 
| 48 | f(y) = f_{0}+\beta y | f(y) = f_{0}+\beta y | 
| 49 | \end{equation} | \end{equation} | 
| 50 |  |  | 
| 51 | \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 | 
| 52 | 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 | 
| 53 | (\ref{EQ:fcori}) and $\beta = 10^{-11}s^{-1}m^{-1}$. | (\ref{EQ:eg-baro-fcori}) and $\beta = 10^{-11}s^{-1}m^{-1}$. | 
| 54 | \\ | \\ | 
| 55 | \\ | \\ | 
| 56 | The sinusoidal wind-stress variations are defined according to | The sinusoidal wind-stress variations are defined according to | 
| 57 |  |  | 
| 58 | \begin{equation} | \begin{equation} | 
| 59 | \label{EQ:taux} | \label{EQ:eg-baro-taux} | 
| 60 | \tau_x(y) = \tau_{0}\sin(\pi \frac{y}{L_y}) | \tau_x(y) = \tau_{0}\sin(\pi \frac{y}{L_y}) | 
| 61 | \end{equation} | \end{equation} | 
| 62 |  |  | 
| 64 | $\tau_0$ is set to $0.1N m^{-2}$. | $\tau_0$ is set to $0.1N m^{-2}$. | 
| 65 | \\ | \\ | 
| 66 | \\ | \\ | 
| 67 | Figure \ref{FIG:simulation_config} | Figure \ref{FIG:eg-baro-simulation_config} | 
| 68 | summarizes the configuration simulated. | summarizes the configuration simulated. | 
| 69 |  |  | 
| 70 | \begin{figure} | \begin{figure} | 
| 76 | \caption{Schematic of simulation domain and wind-stress forcing function | \caption{Schematic of simulation domain and wind-stress forcing function | 
| 77 | for barotropic gyre numerical experiment. The domain is enclosed bu solid | for barotropic gyre numerical experiment. The domain is enclosed bu solid | 
| 78 | walls at $x=$~0,1200km and at $y=$~0,1200km.} | walls at $x=$~0,1200km and at $y=$~0,1200km.} | 
| 79 | \label{FIG:simulation_config} | \label{FIG:eg-baro-simulation_config} | 
| 80 | \end{figure} | \end{figure} | 
| 81 |  |  | 
| 82 | \subsection{Equations Solved} | \subsection{Equations Solved} | 
| 91 | configuration as follows | configuration as follows | 
| 92 |  |  | 
| 93 | \begin{eqnarray} | \begin{eqnarray} | 
| 94 | \label{EQ:model_equations} | \label{EQ:eg-baro-model_equations} | 
| 95 | \frac{Du}{Dt} - fv + | \frac{Du}{Dt} - fv + | 
| 96 | g\frac{\partial \eta}{\partial x} - | g\frac{\partial \eta}{\partial x} - | 
| 97 | A_{h}\nabla_{h}^2u | A_{h}\nabla_{h}^2u | 
| 127 | 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}, | 
| 128 |  |  | 
| 129 | \begin{eqnarray} | \begin{eqnarray} | 
| 130 | \label{EQ:munk_layer} | \label{EQ:eg-baro-munk_layer} | 
| 131 | M_{w} = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}} | M_{w} = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}} | 
| 132 | \end{eqnarray} | \end{eqnarray} | 
| 133 |  |  | 
| 143 |  |  | 
| 144 |  |  | 
| 145 | \begin{eqnarray} | \begin{eqnarray} | 
| 146 | \label{EQ:laplacian_stability} | \label{EQ:eg-baro-laplacian_stability} | 
| 147 | S_{l} = 4 \frac{A_{h} \delta t}{{\Delta x}^2} | S_{l} = 4 \frac{A_{h} \delta t}{{\Delta x}^2} | 
| 148 | \end{eqnarray} | \end{eqnarray} | 
| 149 |  |  | 
| 155 | \cite{adcroft:95} | \cite{adcroft:95} | 
| 156 |  |  | 
| 157 | \begin{eqnarray} | \begin{eqnarray} | 
| 158 | \label{EQ:inertial_stability} | \label{EQ:eg-baro-inertial_stability} | 
| 159 | S_{i} = f^{2} {\delta t}^2 | S_{i} = f^{2} {\delta t}^2 | 
| 160 | \end{eqnarray} | \end{eqnarray} | 
| 161 |  |  | 
| 167 | horizontal flow speed of $ | \vec{u} | = 2 ms^{-1}$ | horizontal flow speed of $ | \vec{u} | = 2 ms^{-1}$ | 
| 168 |  |  | 
| 169 | \begin{eqnarray} | \begin{eqnarray} | 
| 170 | \label{EQ:cfl_stability} | \label{EQ:eg-baro-cfl_stability} | 
| 171 | S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} | S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} | 
| 172 | \end{eqnarray} | \end{eqnarray} | 
| 173 |  |  | 
| 175 | of 0.5 and limits $\delta t$ to $1200s$. | of 0.5 and limits $\delta t$ to $1200s$. | 
| 176 |  |  | 
| 177 | \subsection{Code Configuration} | \subsection{Code Configuration} | 
| 178 | \label{SEC:code_config} | \label{SEC:eg-baro-code_config} | 
| 179 |  |  | 
| 180 | The model configuration for this experiment resides under the | The model configuration for this experiment resides under the | 
| 181 | directory {\it verification/exp0/}.  The experiment files | directory {\it verification/exp0/}.  The experiment files |