--- manual/s_examples/barotropic_gyre/baro.tex 2001/08/08 16:15:49 1.1 +++ manual/s_examples/barotropic_gyre/baro.tex 2004/10/13 05:06:26 1.11 @@ -1,8 +1,6 @@ -% $Header: /home/ubuntu/mnt/e9_copy/manual/s_examples/barotropic_gyre/baro.tex,v 1.1 2001/08/08 16:15:49 adcroft Exp $ +% $Header: /home/ubuntu/mnt/e9_copy/manual/s_examples/barotropic_gyre/baro.tex,v 1.11 2004/10/13 05:06:26 cnh Exp $ % $Name: $ -\section{Example: Barotropic Ocean Gyre In Cartesian Coordinates} - \bodytext{bgcolor="#FFFFFFFF"} %\begin{center} @@ -15,25 +13,26 @@ %{\large May 2001} %\end{center} -\subsection{Introduction} - -This document is the first in a series of documents describing +This is the first in a series of tutorials describing example MITgcm numerical experiments. The example experiments -include both straightforward examples of idealised geophysical +include both straightforward examples of idealized geophysical fluid simulations and more involved cases encompassing large scale modeling and automatic differentiation. Both hydrostatic and non-hydrostatic -experiements are presented, as well as experiments employing -cartesian, spherical-polar and cube-sphere coordinate systems. +experiments are presented, as well as experiments employing +Cartesian, spherical-polar and cube-sphere coordinate systems. These ``case study'' documents include information describing the experimental configuration and detailed information on how to configure the MITgcm code and input files for each experiment. -\subsection{Experiment Overview} +\section[Barotropic Gyre MITgcm Example]{Barotropic Ocean Gyre In Cartesian Coordinates} +\label{sect:eg-baro} +\label{www:tutorials} + This example experiment demonstrates using the MITgcm to simulate -a barotropic, wind-forced, ocean gyre circulation. The experiment -is a numerical rendition of the gyre circulation problem simliar +a Barotropic, wind-forced, ocean gyre circulation. The experiment +is a numerical rendition of the gyre circulation problem similar to the problems described analytically by Stommel in 1966 \cite{Stommel66} and numerically in Holland et. al \cite{Holland75}. @@ -41,24 +40,24 @@ is configured to represent a rectangular enclosed box of fluid, $1200 \times 1200 $~km in lateral extent. The fluid is $5$~km deep and is forced by a constant in time zonal wind stress, $\tau_x$, that varies sinusoidally -in the ``north-south'' direction. Topologically the grid is cartesian and +in the ``north-south'' direction. Topologically the grid is Cartesian and the coriolis parameter $f$ is defined according to a mid-latitude beta-plane equation \begin{equation} -\label{EQ:fcori} +\label{EQ:eg-baro-fcori} f(y) = f_{0}+\beta y \end{equation} \noindent where $y$ is the distance along the ``north-south'' axis of the simulated domain. For this experiment $f_{0}$ is set to $10^{-4}s^{-1}$ in -(\ref{EQ:fcori}) and $\beta = 10^{-11}s^{-1}m^{-1}$. +(\ref{EQ:eg-baro-fcori}) and $\beta = 10^{-11}s^{-1}m^{-1}$. \\ \\ The sinusoidal wind-stress variations are defined according to \begin{equation} -\label{EQ:taux} +\label{EQ:eg-baro-taux} \tau_x(y) = \tau_{0}\sin(\pi \frac{y}{L_y}) \end{equation} @@ -66,48 +65,48 @@ $\tau_0$ is set to $0.1N m^{-2}$. \\ \\ -Figure \ref{FIG:simulation_config} -summarises the configuration simulated. +Figure \ref{FIG:eg-baro-simulation_config} +summarizes the configuration simulated. +%% === eh3 === \begin{figure} +%% \begin{center} +%% \resizebox{7.5in}{5.5in}{ +%% \includegraphics*[0.2in,0.7in][10.5in,10.5in] +%% {part3/case_studies/barotropic_gyre/simulation_config.eps} } +%% \end{center} \centerline{ - \resizebox{7.5in}{5.5in}{ - \includegraphics*[0.2in,0.7in][10.5in,10.5in] - {part3/case_studies/barotropic_gyre/simulation_config.eps} } + \scalefig{.95} + \epsfbox{part3/case_studies/barotropic_gyre/simulation_config.eps} } \caption{Schematic of simulation domain and wind-stress forcing function for barotropic gyre numerical experiment. The domain is enclosed bu solid walls at $x=$~0,1200km and at $y=$~0,1200km.} -\label{FIG:simulation_config} +\label{FIG:eg-baro-simulation_config} \end{figure} -\subsection{Discrete Numerical Configuration} - - The model is configured in hydrostatic form. The domain is discretised with -a uniform grid spacing in the horizontal set to - $\Delta x=\Delta y=20$~km, so -that there are sixty grid cells in the $x$ and $y$ directions. Vertically the -model is configured with a single layer with depth, $\Delta z$, of $5000$~m. -The implicit free surface form of the -pressure equation described in Marshall et. al \cite{Marshall97a} is -employed. -A horizontal laplacian operator $\nabla_{h}^2$ provides viscous +\subsection{Equations Solved} +\label{www:tutorials} +The model is configured in hydrostatic form. The implicit free surface form of the +pressure equation described in Marshall et. al \cite{marshall:97a} is +employed. +A horizontal Laplacian operator $\nabla_{h}^2$ provides viscous dissipation. The wind-stress momentum input is added to the momentum equation for the ``zonal flow'', $u$. Other terms in the model -are explicitly switched off for this experiement configuration (see section -\ref{SEC:code_config} ), yielding an active set of equations solved in this -configuration as follows +are explicitly switched off for this experiment configuration (see section +\ref{SEC:code_config} ), yielding an active set of equations solved in this +configuration as follows \begin{eqnarray} -\label{EQ:model_equations} -\frac{Du}{Dt} - fv + - g\frac{\partial \eta}{\partial x} - - A_{h}\nabla_{h}^2u +\label{EQ:eg-baro-model_equations} +\frac{Du}{Dt} - fv + + g\frac{\partial \eta}{\partial x} - + A_{h}\nabla_{h}^2u & = & \frac{\tau_{x}}{\rho_{0}\Delta z} \\ \frac{Dv}{Dt} + fu + g\frac{\partial \eta}{\partial y} - - A_{h}\nabla_{h}^2v + A_{h}\nabla_{h}^2v & = & 0 \\ @@ -117,16 +116,27 @@ \end{eqnarray} \noindent where $u$ and $v$ and the $x$ and $y$ components of the -flow vector $\vec{u}$. +flow vector $\vec{u}$. \\ + +\subsection{Discrete Numerical Configuration} +\label{www:tutorials} + + The domain is discretised with +a uniform grid spacing in the horizontal set to + $\Delta x=\Delta y=20$~km, so +that there are sixty grid cells in the $x$ and $y$ directions. Vertically the +model is configured with a single layer with depth, $\Delta z$, of $5000$~m. + \subsubsection{Numerical Stability Criteria} +\label{www:tutorials} -The laplacian dissipation coefficient, $A_{h}$, is set to $400 m s^{-1}$. -This value is chosen to yield a Munk layer width \cite{Adcroft_thesis}, +The Laplacian dissipation coefficient, $A_{h}$, is set to $400 m s^{-1}$. +This value is chosen to yield a Munk layer width \cite{adcroft:95}, \begin{eqnarray} -\label{EQ:munk_layer} +\label{EQ:eg-baro-munk_layer} M_{w} = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}} \end{eqnarray} @@ -137,12 +147,12 @@ \noindent The model is stepped forward with a time step $\delta t=1200$secs. With this time step the stability -parameter to the horizontal laplacian friction \cite{Adcroft_thesis} +parameter to the horizontal Laplacian friction \cite{adcroft:95} \begin{eqnarray} -\label{EQ:laplacian_stability} +\label{EQ:eg-baro-laplacian_stability} S_{l} = 4 \frac{A_{h} \delta t}{{\Delta x}^2} \end{eqnarray} @@ -151,10 +161,10 @@ \\ \noindent The numerical stability for inertial oscillations -\cite{Adcroft_thesis} +\cite{adcroft:95} \begin{eqnarray} -\label{EQ:inertial_stability} +\label{EQ:eg-baro-inertial_stability} S_{i} = f^{2} {\delta t}^2 \end{eqnarray} @@ -162,11 +172,11 @@ limit for stability. \\ -\noindent The advective CFL \cite{Adcroft_thesis} for an extreme maximum +\noindent The advective CFL \cite{adcroft:95} for an extreme maximum horizontal flow speed of $ | \vec{u} | = 2 ms^{-1}$ \begin{eqnarray} -\label{EQ:cfl_stability} +\label{EQ:eg-baro-cfl_stability} S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} \end{eqnarray} @@ -174,7 +184,8 @@ of 0.5 and limits $\delta t$ to $1200s$. \subsection{Code Configuration} -\label{SEC:code_config} +\label{www:tutorials} +\label{SEC:eg-baro-code_config} The model configuration for this experiment resides under the directory {\it verification/exp0/}. The experiment files @@ -188,11 +199,12 @@ \item {\it code/CPP\_OPTIONS.h}, \item {\it code/SIZE.h}. \end{itemize} -contain the code customisations and parameter settings for this -experiements. Below we describe the customisations +contain the code customizations and parameter settings for this +experiments. Below we describe the customizations to these files associated with this experiment. \subsubsection{File {\it input/data}} +\label{www:tutorials} This file, reproduced completely below, specifies the main parameters for the experiment. The parameters that are significant for this configuration @@ -201,7 +213,7 @@ \begin{itemize} \item Line 7, \begin{verbatim} viscAh=4.E2, \end{verbatim} this line sets -the laplacian friction coefficient to $400 m^2s^{-1}$ +the Laplacian friction coefficient to $400 m^2s^{-1}$ \item Line 10, \begin{verbatim} beta=1.E-11, \end{verbatim} this line sets $\beta$ (the gradient of the coriolis parameter, $f$) to $10^{-11} s^{-1}m^{-1}$ @@ -219,7 +231,7 @@ startTime=0, \end{verbatim} this line indicates that the experiment should start from $t=0$ -and implicitly supresses searching for checkpoint files associated +and implicitly suppresses searching for checkpoint files associated with restarting an numerical integration from a previously saved state. \item Line 29, @@ -241,7 +253,7 @@ usingCartesianGrid=.TRUE., \end{verbatim} This line requests that the simulation be performed in a -cartesian coordinate system. +Cartesian coordinate system. \item Line 41, \begin{verbatim} @@ -304,16 +316,19 @@ \end{small} \subsubsection{File {\it input/data.pkg}} +\label{www:tutorials} This file uses standard default values and does not contain -customisations for this experiment. +customizations for this experiment. \subsubsection{File {\it input/eedata}} +\label{www:tutorials} This file uses standard default values and does not contain -customisations for this experiment. +customizations for this experiment. \subsubsection{File {\it input/windx.sin\_y}} +\label{www:tutorials} The {\it input/windx.sin\_y} file specifies a two-dimensional ($x,y$) map of wind stress ,$\tau_{x}$, values. The units used are $Nm^{-2}$. @@ -324,6 +339,7 @@ code for creating the {\it input/windx.sin\_y} file. \subsubsection{File {\it input/topog.box}} +\label{www:tutorials} The {\it input/topog.box} file specifies a two-dimensional ($x,y$) @@ -335,6 +351,7 @@ code for creating the {\it input/topog.box} file. \subsubsection{File {\it code/SIZE.h}} +\label{www:tutorials} Two lines are customized in this file for the current experiment @@ -357,13 +374,15 @@ \end{small} \subsubsection{File {\it code/CPP\_OPTIONS.h}} +\label{www:tutorials} This file uses standard default values and does not contain -customisations for this experiment. +customizations for this experiment. \subsubsection{File {\it code/CPP\_EEOPTIONS.h}} +\label{www:tutorials} This file uses standard default values and does not contain -customisations for this experiment. +customizations for this experiment.