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\section{Example: Four layer Baroclinic Ocean Gyre In Spherical Coordinates} |
\section{Four Layer Baroclinic Ocean Gyre In Spherical Coordinates} |
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\label{www:tutorials} |
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\label{sect:eg-fourlayer} |
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\bodytext{bgcolor="#FFFFFFFF"} |
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%{\large May 2001} |
%{\large May 2001} |
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%\end{center} |
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\subsection{Introduction} |
This document describes an example experiment using MITgcm |
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to simulate a baroclinic ocean gyre in spherical |
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This document describes the second example MITgcm experiment. The first |
polar coordinates. The barotropic |
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example experiment ilustrated how to configure the code for a single layer |
example experiment in section \ref{sect:eg-baro} |
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simulation in a cartesian grid. In this example a similar physical problem |
illustrated how to configure the code for a single layer |
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simulation in a Cartesian grid. In this example a similar physical problem |
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is simulated, but the code is now configured |
is simulated, but the code is now configured |
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for four layers and in a spherical polar coordinate system. |
for four layers and in a spherical polar coordinate system. |
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\subsection{Overview} |
\subsection{Overview} |
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\label{www:tutorials} |
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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 baroclinic, wind-forced, ocean gyre circulation. The experiment |
a baroclinic, wind-forced, ocean gyre circulation. The experiment |
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is a numerical rendition of the gyre circulation problem simliar |
is a numerical rendition of the gyre circulation problem similar |
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to the problems described analytically by Stommel in 1966 |
to the problems described analytically by Stommel in 1966 |
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\cite{Stommel66} and numerically in Holland et. al \cite{Holland75}. |
\cite{Stommel66} and numerically in Holland et. al \cite{Holland75}. |
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\\ |
\\ |
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In this experiment the model is configured to represent a mid-latitude |
In this experiment the model is configured to represent a mid-latitude |
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enclosed sector of fluid on a sphere, $60^{\circ} \times 60^{\circ}$ in |
enclosed sector of fluid on a sphere, $60^{\circ} \times 60^{\circ}$ in |
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lateral extent. The fluid is $2$~km deep and is forced |
lateral extent. The fluid is $2$~km deep and is forced |
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by a constant in time zonal wind stress, $\tau_x$, that varies sinusoidally |
by a constant in time zonal wind stress, $\tau_{\lambda}$, that varies |
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in the north-south direction. Topologically the simulated |
sinusoidally in the north-south direction. Topologically the simulated |
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domain is a sector on a sphere and the coriolis parameter, $f$, is defined |
domain is a sector on a sphere and the coriolis parameter, $f$, is defined |
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according to latitude, $\phi$ |
according to latitude, $\varphi$ |
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|
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\begin{equation} |
\begin{equation} |
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\label{EQ:fcori} |
\label{EQ:eg-fourlayer-fcori} |
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f(\phi) = 2 \Omega \sin( \phi ) |
f(\varphi) = 2 \Omega \sin( \varphi ) |
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\end{equation} |
\end{equation} |
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|
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\noindent with the rotation rate, $\Omega$ set to $\frac{2 \pi}{86400s}$. |
\noindent with the rotation rate, $\Omega$ set to $\frac{2 \pi}{86400s}$. |
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|
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\begin{equation} |
\begin{equation} |
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\label{EQ:taux} |
\label{EQ:taux} |
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\tau_x(\phi) = \tau_{0}\sin(\pi \frac{\phi}{L_{\phi}}) |
\tau_{\lambda}(\varphi) = \tau_{0}\sin(\pi \frac{\varphi}{L_{\varphi}}) |
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\end{equation} |
\end{equation} |
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|
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\noindent where $L_{\phi}$ is the lateral domain extent ($60^{\circ}$) and |
\noindent where $L_{\varphi}$ is the lateral domain extent ($60^{\circ}$) and |
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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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\\ |
\\ |
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Figure \ref{FIG:simulation_config} |
Figure \ref{FIG:eg-fourlayer-simulation_config} |
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summarises the configuration simulated. |
summarizes the configuration simulated. |
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In contrast to example (1) \cite{baro_gyre_case_study}, the current |
In contrast to the example in section \ref{sect:eg-baro}, the |
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experiment simulates a spherical polar domain. However, as indicated |
current experiment simulates a spherical polar domain. As indicated |
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by the axes in the lower left of the figure the model code works internally |
by the axes in the lower left of the figure the model code works internally |
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in a locally orthoganal coordinate $(x,y,z)$. In the remainder of this |
in a locally orthogonal coordinate $(x,y,z)$. For this experiment description |
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document the local coordinate $(x,y,z)$ will be adopted. |
the local orthogonal model coordinate $(x,y,z)$ is synonymous |
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with the coordinates $(\lambda,\varphi,r)$ shown in figure |
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\ref{fig:spherical-polar-coord} |
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\\ |
\\ |
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The experiment has four levels in the vertical, each of equal thickness, |
The experiment has four levels in the vertical, each of equal thickness, |
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linear |
linear |
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|
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\begin{equation} |
\begin{equation} |
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\label{EQ:linear1_eos} |
\label{EQ:eg-fourlayer-linear1_eos} |
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\rho = \rho_{0} ( 1 - \alpha_{\theta}\theta^{'} ) |
\rho = \rho_{0} ( 1 - \alpha_{\theta}\theta^{'} ) |
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\end{equation} |
\end{equation} |
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\noindent which is implemented in the model as a density anomaly equation |
\noindent which is implemented in the model as a density anomaly equation |
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\begin{equation} |
\begin{equation} |
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\label{EQ:linear1_eos_pert} |
\label{EQ:eg-fourlayer-linear1_eos_pert} |
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\rho^{'} = -\rho_{0}\alpha_{\theta}\theta^{'} |
\rho^{'} = -\rho_{0}\alpha_{\theta}\theta^{'} |
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\end{equation} |
\end{equation} |
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\noindent with $\rho_{0}=999.8\,{\rm kg\,m}^{-3}$ and |
\noindent with $\rho_{0}=999.8\,{\rm kg\,m}^{-3}$ and |
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$\alpha_{\theta}=2\times10^{-4}\,{\rm degrees}^{-1} $. Integrated forward in |
$\alpha_{\theta}=2\times10^{-4}\,{\rm degrees}^{-1} $. Integrated forward in |
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this configuration the model state variable {\bf theta} is synonomous with |
this configuration the model state variable {\bf theta} is equivalent to |
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either in-situ temperature, $T$, or potential temperature, $\theta$. For |
either in-situ temperature, $T$, or potential temperature, $\theta$. For |
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consistency with later examples, in which the equation of state is |
consistency with later examples, in which the equation of state is |
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non-linear, we use $\theta$ to represent temperature here. This is |
non-linear, we use $\theta$ to represent temperature here. This is |
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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 the four-layer gyre numerical experiment. The domain is enclosed by solid |
for the four-layer gyre numerical experiment. The domain is enclosed by solid |
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walls at $0^{\circ}$~E, $60^{\circ}$~E, $0^{\circ}$~N and $60^{\circ}$~N. |
walls at $0^{\circ}$~E, $60^{\circ}$~E, $0^{\circ}$~N and $60^{\circ}$~N. |
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In the four-layer case an initial temperature stratification is |
An initial stratification is |
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imposed by setting the potential temperature, $\theta$, in each layer. |
imposed by setting the potential temperature, $\theta$, in each layer. |
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The vertical spacing, $\Delta z$, is constant and equal to $500$m. |
The vertical spacing, $\Delta z$, is constant and equal to $500$m. |
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} |
} |
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\label{FIG:simulation_config} |
\label{FIG:eg-fourlayer-simulation_config} |
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\end{figure} |
\end{figure} |
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\subsection{Discrete Numerical Configuration} |
\subsection{Equations solved} |
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|
\label{www:tutorials} |
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The model is configured in hydrostatic form. The domain is discretised with |
For this problem |
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a uniform grid spacing in latitude and longitude |
the implicit free surface, {\bf HPE} (see section \ref{sect:hydrostatic_and_quasi-hydrostatic_forms}) form of the |
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$\Delta x=\Delta y=1^{\circ}$, so |
equations described in Marshall et. al \cite{marshall:97a} are |
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that there are sixty grid cells in the $x$ and $y$ directions. Vertically the |
employed. The flow is three-dimensional with just temperature, $\theta$, as |
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model is configured with a four layers with constant depth, |
an active tracer. The equation of state is linear. |
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$\Delta z$, of $500$~m. |
A horizontal Laplacian operator $\nabla_{h}^2$ provides viscous |
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The implicit free surface form of the |
dissipation and provides a diffusive sub-grid scale closure for the |
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pressure equation described in Marshall et. al \cite{Marshall97a} is |
temperature equation. A wind-stress momentum forcing is added to the momentum |
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employed. |
equation for the zonal flow, $u$. Other terms in the model |
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A horizontal laplacian operator $\nabla_{h}^2$ provides viscous |
are explicitly switched off for this experiment configuration (see section |
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dissipation. The wind-stress momentum input is added to the momentum equation |
\ref{SEC:eg_fourl_code_config} ). This yields an active set of equations |
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for the ``zonal flow'', $u$. Other terms in the model |
solved in this configuration, written in spherical polar coordinates as |
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are explicitly switched off for this experiement configuration (see section |
follows |
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\ref{SEC:code_config} ), yielding an active set of equations solved in this |
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configuration as follows |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:model_equations} |
\label{EQ:eg-fourlayer-model_equations} |
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\frac{Du}{Dt} - fv + |
\frac{Du}{Dt} - fv + |
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\frac{1}{\rho}\frac{\partial p^{'}}{\partial x} - |
\frac{1}{\rho}\frac{\partial p^{\prime}}{\partial \lambda} - |
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A_{h}\nabla_{h}^2u - A_{z}\frac{\partial^{2}u}{\partial z^{2}} |
A_{h}\nabla_{h}^2u - A_{z}\frac{\partial^{2}u}{\partial z^{2}} |
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& = & |
& = & |
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\cal{F} |
\cal{F}_{\lambda} |
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\\ |
\\ |
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\frac{Dv}{Dt} + fu + |
\frac{Dv}{Dt} + fu + |
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\frac{1}{\rho}\frac{\partial p^{'}}{\partial y} - |
\frac{1}{\rho}\frac{\partial p^{\prime}}{\partial \varphi} - |
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A_{h}\nabla_{h}^2v - A_{z}\frac{\partial^{2}v}{\partial z^{2}} |
A_{h}\nabla_{h}^2v - A_{z}\frac{\partial^{2}v}{\partial z^{2}} |
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& = & |
& = & |
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0 |
0 |
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\\ |
\\ |
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\frac{\partial \eta}{\partial t} + \nabla_{h}\cdot \vec{u} |
\frac{\partial \eta}{\partial t} + \frac{\partial H \widehat{u}}{\partial \lambda} + |
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\frac{\partial H \widehat{v}}{\partial \varphi} |
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&=& |
&=& |
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0 |
0 |
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\label{eq:fourl_example_continuity} |
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\\ |
\\ |
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\frac{D\theta}{Dt} - |
\frac{D\theta}{Dt} - |
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K_{h}\nabla_{h}^2\theta - K_{z}\frac{\partial^{2}\theta}{\partial z^{2}} |
K_{h}\nabla_{h}^2\theta - K_{z}\frac{\partial^{2}\theta}{\partial z^{2}} |
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& = & |
& = & |
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0 |
0 |
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\label{eq:eg_fourl_theta} |
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\\ |
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p^{\prime} & = & |
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g\rho_{0} \eta + \int^{0}_{-z}\rho^{\prime} dz |
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\\ |
\\ |
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g\rho_{0} \eta + \int^{0}_{-z}\rho^{'} dz & = & p^{'} |
\rho^{\prime} & = &- \alpha_{\theta}\rho_{0}\theta^{\prime} |
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\\ |
\\ |
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{\cal F} |_{s} & = & \frac{\tau_{x}}{\rho_{0}\Delta z_{s}} |
{\cal F}_{\lambda} |_{s} & = & \frac{\tau_{\lambda}}{\rho_{0}\Delta z_{s}} |
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\\ |
\\ |
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{\cal F} |_{i} & = & 0 |
{\cal F}_{\lambda} |_{i} & = & 0 |
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\end{eqnarray} |
\end{eqnarray} |
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|
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\noindent where $u$ and $v$ are the $x$ and $y$ components of the |
\noindent where $u$ and $v$ are the components of the horizontal |
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flow vector $\vec{u}$. The suffices ${s},{i}$ indicate surface and |
flow vector $\vec{u}$ on the sphere ($u=\dot{\lambda},v=\dot{\varphi}$). |
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interior model levels respectively. As described in |
The terms $H\widehat{u}$ and $H\widehat{v}$ are the components of the vertical |
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MITgcm Numerical Solution Procedure \cite{MITgcm_Numerical_Scheme}, the time |
integral term given in equation \ref{eq:free-surface} and |
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evolution of potential temperature, $\theta$, equation is solved prognostically. |
explained in more detail in section \ref{sect:pressure-method-linear-backward}. |
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The total pressure, $p$, is diagnosed by summing pressure due to surface |
However, for the problem presented here, the continuity relation (equation |
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elevation $\eta$ and the hydrostatic pressure. |
\ref{eq:fourl_example_continuity}) differs from the general form given |
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\\ |
in section \ref{sect:pressure-method-linear-backward}, |
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equation \ref{eq:linear-free-surface=P-E+R}, because the source terms |
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${\cal P}-{\cal E}+{\cal R}$ |
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are all $0$. |
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The pressure field, $p^{\prime}$, is separated into a barotropic part |
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due to variations in sea-surface height, $\eta$, and a hydrostatic |
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part due to variations in density, $\rho^{\prime}$, integrated |
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through the water column. |
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The suffices ${s},{i}$ indicate surface layer and the interior of the domain. |
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The windstress forcing, ${\cal F}_{\lambda}$, is applied in the surface layer |
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by a source term in the zonal momentum equation. In the ocean interior |
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this term is zero. |
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In the momentum equations |
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lateral and vertical boundary conditions for the $\nabla_{h}^{2}$ |
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and $\frac{\partial^{2}}{\partial z^{2}}$ operators are specified |
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when the numerical simulation is run - see section |
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\ref{SEC:eg_fourl_code_config}. For temperature |
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the boundary condition is ``zero-flux'' |
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e.g. $\frac{\partial \theta}{\partial \varphi}= |
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\frac{\partial \theta}{\partial \lambda}=\frac{\partial \theta}{\partial z}=0$. |
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\subsection{Discrete Numerical Configuration} |
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\label{www:tutorials} |
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The domain is discretised with |
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a uniform grid spacing in latitude and longitude |
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$\Delta \lambda=\Delta \varphi=1^{\circ}$, so |
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that there are sixty grid cells in the zonal and meridional directions. |
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Vertically the |
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model is configured with four layers with constant depth, |
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$\Delta z$, of $500$~m. The internal, locally orthogonal, model coordinate |
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variables $x$ and $y$ are initialized from the values of |
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$\lambda$, $\varphi$, $\Delta \lambda$ and $\Delta \varphi$ in |
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radians according to |
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\begin{eqnarray} |
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x=r\cos(\varphi)\lambda,~\Delta x & = &r\cos(\varphi)\Delta \lambda \\ |
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y=r\varphi,~\Delta y &= &r\Delta \varphi |
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\end{eqnarray} |
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The procedure for generating a set of internal grid variables from a |
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spherical polar grid specification is discussed in section |
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\ref{sect:spatial_discrete_horizontal_grid}. |
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\noindent\fbox{ \begin{minipage}{5.5in} |
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{\em S/R INI\_SPHERICAL\_POLAR\_GRID} ({\em |
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model/src/ini\_spherical\_polar\_grid.F}) |
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$A_c$, $A_\zeta$, $A_w$, $A_s$: {\bf rAc}, {\bf rAz}, {\bf rAw}, {\bf rAs} |
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({\em GRID.h}) |
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$\Delta x_g$, $\Delta y_g$: {\bf DXg}, {\bf DYg} ({\em GRID.h}) |
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$\Delta x_c$, $\Delta y_c$: {\bf DXc}, {\bf DYc} ({\em GRID.h}) |
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$\Delta x_f$, $\Delta y_f$: {\bf DXf}, {\bf DYf} ({\em GRID.h}) |
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$\Delta x_v$, $\Delta y_u$: {\bf DXv}, {\bf DYu} ({\em GRID.h}) |
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\end{minipage} }\\ |
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As described in \ref{sect:tracer_equations}, the time evolution of potential |
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temperature, |
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$\theta$, (equation \ref{eq:eg_fourl_theta}) |
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is evaluated prognostically. The centered second-order scheme with |
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Adams-Bashforth time stepping described in section |
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\ref{sect:tracer_equations_abII} is used to step forward the temperature |
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equation. Prognostic terms in |
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the momentum equations are solved using flux form as |
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described in section \ref{sect:flux-form_momentum_eqautions}. |
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The pressure forces that drive the fluid motions, ( |
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$\frac{\partial p^{'}}{\partial \lambda}$ and $\frac{\partial p^{'}}{\partial \varphi}$), are found by summing pressure due to surface |
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elevation $\eta$ and the hydrostatic pressure. The hydrostatic part of the |
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pressure is diagnosed explicitly by integrating density. The sea-surface |
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height, $\eta$, is diagnosed using an implicit scheme. The pressure |
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field solution method is described in sections |
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\ref{sect:pressure-method-linear-backward} and |
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\ref{sect:finding_the_pressure_field}. |
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\subsubsection{Numerical Stability Criteria} |
\subsubsection{Numerical Stability Criteria} |
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\label{www:tutorials} |
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|
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The laplacian dissipation coefficient, $A_{h}$, is set to $400 m s^{-1}$. |
The Laplacian viscosity coefficient, $A_{h}$, is set to $400 m s^{-1}$. |
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This value is chosen to yield a Munk layer width \cite{Adcroft_thesis}, |
This value is chosen to yield a Munk layer width, |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:munk_layer} |
\label{EQ:eg-fourlayer-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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\noindent of $\approx 100$km. This is greater than the model |
\noindent of $\approx 100$km. This is greater than the model |
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resolution in mid-latitudes $\Delta x$, ensuring that the frictional |
resolution in mid-latitudes |
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$\Delta x=r \cos(\varphi) \Delta \lambda \approx 80~{\rm km}$ at |
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$\varphi=45^{\circ}$, ensuring that the frictional |
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boundary layer is well resolved. |
boundary layer is well resolved. |
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\\ |
\\ |
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\noindent The model is stepped forward with a |
\noindent The model is stepped forward with a |
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time step $\delta t=1200$secs. With this time step the stability |
time step $\delta t=1200$secs. With this time step the stability |
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parameter to the horizontal laplacian friction \cite{Adcroft_thesis} |
parameter to the horizontal Laplacian friction |
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|
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:laplacian_stability} |
\label{EQ:eg-fourlayer-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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\noindent evaluates to 0.012, which is well below the 0.3 upper limit |
\noindent evaluates to 0.012, which is well below the 0.3 upper limit |
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for stability. |
for stability for this term under ABII time-stepping. |
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\\ |
\\ |
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\noindent The vertical dissipation coefficient, $A_{z}$, is set to |
\noindent The vertical dissipation coefficient, $A_{z}$, is set to |
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$1\times10^{-2} {\rm m}^2{\rm s}^{-1}$. The associated stability limit |
$1\times10^{-2} {\rm m}^2{\rm s}^{-1}$. The associated stability limit |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:laplacian_stability_z} |
\label{EQ:eg-fourlayer-laplacian_stability_z} |
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S_{l} = 4 \frac{A_{z} \delta t}{{\Delta z}^2} |
S_{l} = 4 \frac{A_{z} \delta t}{{\Delta z}^2} |
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\end{eqnarray} |
\end{eqnarray} |
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\\ |
\\ |
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\noindent The numerical stability for inertial oscillations |
\noindent The numerical stability for inertial oscillations |
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\cite{Adcroft_thesis} |
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:inertial_stability} |
\label{EQ:eg-fourlayer-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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limit for stability. |
limit for stability. |
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\\ |
\\ |
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\noindent The advective CFL \cite{Adcroft_thesis} for a extreme maximum |
\noindent The advective CFL for a extreme maximum |
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horizontal flow |
horizontal flow |
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speed of $ | \vec{u} | = 2 ms^{-1}$ |
speed of $ | \vec{u} | = 2 ms^{-1}$ |
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|
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\begin{eqnarray} |
\begin{eqnarray} |
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\label{EQ:cfl_stability} |
\label{EQ:eg-fourlayer-cfl_stability} |
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S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} |
C_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} |
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\end{eqnarray} |
\end{eqnarray} |
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\noindent evaluates to $5 \times 10^{-2}$. This is well below the stability |
\noindent evaluates to $5 \times 10^{-2}$. This is well below the stability |
333 |
limit of 0.5. |
limit of 0.5. |
334 |
\\ |
\\ |
335 |
|
|
336 |
\noindent The stability parameter for internal gravity waves |
\noindent The stability parameter for internal gravity waves |
337 |
\cite{Adcroft_thesis} |
propagating at $2~{\rm m}~{\rm s}^{-1}$ |
338 |
|
|
339 |
\begin{eqnarray} |
\begin{eqnarray} |
340 |
\label{EQ:igw_stability} |
\label{EQ:eg-fourlayer-igw_stability} |
341 |
S_{c} = \frac{c_{g} \delta t}{ \Delta x} |
S_{c} = \frac{c_{g} \delta t}{ \Delta x} |
342 |
\end{eqnarray} |
\end{eqnarray} |
343 |
|
|
344 |
\noindent evaluates to $5 \times 10^{-2}$. This is well below the linear |
\noindent evaluates to $\approx 5 \times 10^{-2}$. This is well below the linear |
345 |
stability limit of 0.25. |
stability limit of 0.25. |
346 |
|
|
347 |
\subsection{Code Configuration} |
\subsection{Code Configuration} |
348 |
\label{SEC:code_config} |
\label{www:tutorials} |
349 |
|
\label{SEC:eg_fourl_code_config} |
350 |
|
|
351 |
The model configuration for this experiment resides under the |
The model configuration for this experiment resides under the |
352 |
directory {\it verification/exp1/}. The experiment files |
directory {\it verification/exp2/}. The experiment files |
353 |
\begin{itemize} |
\begin{itemize} |
354 |
\item {\it input/data} |
\item {\it input/data} |
355 |
\item {\it input/data.pkg} |
\item {\it input/data.pkg} |
361 |
\item {\it code/SIZE.h}. |
\item {\it code/SIZE.h}. |
362 |
\end{itemize} |
\end{itemize} |
363 |
contain the code customisations and parameter settings for this |
contain the code customisations and parameter settings for this |
364 |
experiements. Below we describe the customisations |
experiments. Below we describe the customisations |
365 |
to these files associated with this experiment. |
to these files associated with this experiment. |
366 |
|
|
367 |
\subsubsection{File {\it input/data}} |
\subsubsection{File {\it input/data}} |
368 |
|
\label{www:tutorials} |
369 |
|
|
370 |
This file, reproduced completely below, specifies the main parameters |
This file, reproduced completely below, specifies the main parameters |
371 |
for the experiment. The parameters that are significant for this configuration |
for the experiment. The parameters that are significant for this configuration |
379 |
the initial and reference values of potential temperature at each model |
the initial and reference values of potential temperature at each model |
380 |
level in units of $^{\circ}$C. |
level in units of $^{\circ}$C. |
381 |
The entries are ordered from surface to depth. For each |
The entries are ordered from surface to depth. For each |
382 |
depth level the inital and reference profiles will be uniform in |
depth level the initial and reference profiles will be uniform in |
383 |
$x$ and $y$. The values specified here are read into the |
$x$ and $y$. The values specified here are read into the |
384 |
variable |
variable |
385 |
{\bf |
{\bf |
425 |
|
|
426 |
\item Line 6, |
\item Line 6, |
427 |
\begin{verbatim} viscAz=1.E-2, \end{verbatim} |
\begin{verbatim} viscAz=1.E-2, \end{verbatim} |
428 |
this line sets the vertical laplacian dissipation coefficient to |
this line sets the vertical Laplacian dissipation coefficient to |
429 |
$1 \times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary conditions |
$1 \times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary conditions |
430 |
for this operator are specified later. |
for this operator are specified later. |
431 |
The variable |
The variable |
445 |
\begin{rawhtml} <A href=../../../code_reference/vdb/names/PF.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/names/PF.htm> \end{rawhtml} |
446 |
viscAr |
viscAr |
447 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
448 |
}. |
}. At each time step, the viscous term contribution to the momentum equations |
449 |
|
is calculated in routine |
450 |
|
{\it S/R CALC\_DIFFUSIVITY}. |
451 |
|
|
452 |
\fbox{ |
\fbox{ |
453 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
478 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
479 |
INI\_PARMS |
INI\_PARMS |
480 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
481 |
}. |
} and applied in routines {\it CALC\_MOM\_RHS} and {\it CALC\_GW}. |
482 |
|
|
483 |
\fbox{ |
\fbox{ |
484 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
521 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
522 |
INI\_PARMS |
INI\_PARMS |
523 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
524 |
}. |
} and the boundary condition is evaluated in routine |
525 |
|
{\it S/R CALC\_MOM\_RHS}. |
526 |
|
|
527 |
|
|
528 |
\fbox{ |
\fbox{ |
554 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
555 |
INI\_PARMS |
INI\_PARMS |
556 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
557 |
}. |
} and is applied in the routine {\it S/R CALC\_MOM\_RHS}. |
558 |
|
|
559 |
\fbox{ |
\fbox{ |
560 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
586 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
587 |
INI\_PARMS |
INI\_PARMS |
588 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
589 |
}. |
} and used in routine {\it S/R CALC\_GT}. |
590 |
|
|
591 |
\fbox{ \begin{minipage}{5.0in} |
\fbox{ \begin{minipage}{5.0in} |
592 |
{\it S/R CALC\_GT}({\it calc\_gt.F}) |
{\it S/R CALC\_GT}({\it calc\_gt.F}) |
622 |
\begin{rawhtml} <A href=../../../code_reference/vdb/names/PD.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/names/PD.htm> \end{rawhtml} |
623 |
diffKrT |
diffKrT |
624 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
625 |
}. |
} which is used in routine {\it S/R CALC\_DIFFUSIVITY}. |
626 |
|
|
627 |
\fbox{ \begin{minipage}{5.0in} |
\fbox{ \begin{minipage}{5.0in} |
628 |
{\it S/R CALC\_DIFFUSIVITY}({\it calc\_diffusivity.F}) |
{\it S/R CALC\_DIFFUSIVITY}({\it calc\_diffusivity.F}) |
653 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
654 |
INI\_PARMS |
INI\_PARMS |
655 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
656 |
}. |
}. The routine {\it S/R FIND\_RHO} makes use of {\bf tAlpha}. |
657 |
|
|
658 |
\fbox{ |
\fbox{ |
659 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
682 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
683 |
INI\_PARMS |
INI\_PARMS |
684 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
685 |
}. |
}. The values of {\bf eosType} sets which formula in routine |
686 |
|
{\it FIND\_RHO} is used to calculate density. |
687 |
|
|
688 |
\fbox{ |
\fbox{ |
689 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
704 |
\end{verbatim} |
\end{verbatim} |
705 |
This line requests that the simulation be performed in a |
This line requests that the simulation be performed in a |
706 |
spherical polar coordinate system. It affects the interpretation of |
spherical polar coordinate system. It affects the interpretation of |
707 |
grid inoput parameters, for exampl {\bf delX} and {\bf delY} and |
grid input parameters, for example {\bf delX} and {\bf delY} and |
708 |
causes the grid generation routines to initialise an internal grid based |
causes the grid generation routines to initialize an internal grid based |
709 |
on spherical polar geometry. |
on spherical polar geometry. |
710 |
The variable |
The variable |
711 |
{\bf |
{\bf |
718 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
719 |
INI\_PARMS |
INI\_PARMS |
720 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
721 |
}. |
}. When set to {\bf .TRUE.} the settings of {\bf delX} and {\bf delY} are |
722 |
|
taken to be in degrees. These values are used in the |
723 |
|
routine {\it INI\_SPEHRICAL\_POLAR\_GRID}. |
724 |
|
|
725 |
\fbox{ |
\fbox{ |
726 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
740 |
This line sets the southern boundary of the modeled |
This line sets the southern boundary of the modeled |
741 |
domain to $0^{\circ}$ latitude. This value affects both the |
domain to $0^{\circ}$ latitude. This value affects both the |
742 |
generation of the locally orthogonal grid that the model |
generation of the locally orthogonal grid that the model |
743 |
uses internally and affects the initialisation of the coriolis force. |
uses internally and affects the initialization of the coriolis force. |
744 |
Note - it is not required to set |
Note - it is not required to set |
745 |
a longitude boundary, since the absolute longitude does |
a longitude boundary, since the absolute longitude does |
746 |
not alter the kernel equation discretisation. |
not alter the kernel equation discretisation. |
755 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
756 |
INI\_PARMS |
INI\_PARMS |
757 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
758 |
}. |
} and is used in routine {\it INI\_SPEHRICAL\_POLAR\_GRID}. |
759 |
|
|
760 |
\fbox{ |
\fbox{ |
761 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
785 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
786 |
INI\_PARMS |
INI\_PARMS |
787 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
788 |
}. |
} and is used in routine {\it INI\_SPEHRICAL\_POLAR\_GRID}. |
789 |
|
|
790 |
\fbox{ |
\fbox{ |
791 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
815 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
816 |
INI\_PARMS |
INI\_PARMS |
817 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
818 |
}. |
} and is used in routine {\it INI\_SPEHRICAL\_POLAR\_GRID}. |
819 |
|
|
820 |
\fbox{ |
\fbox{ |
821 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
853 |
\begin{rawhtml} <A href=../../../code_reference/vdb/names/10Y.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/names/10Y.htm> \end{rawhtml} |
854 |
delR |
delR |
855 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
856 |
}. |
} which is used in routine {\it INI\_VERTICAL\_GRID}. |
857 |
|
|
858 |
\fbox{ |
\fbox{ |
859 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
892 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
893 |
INI\_PARMS |
INI\_PARMS |
894 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
895 |
}. |
}. The bathymetry file is read in the routine {\it INI\_DEPTHS}. |
896 |
|
|
897 |
\fbox{ |
\fbox{ |
898 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
911 |
zonalWindFile='windx.sin_y' |
zonalWindFile='windx.sin_y' |
912 |
\end{verbatim} |
\end{verbatim} |
913 |
This line specifies the name of the file from which the x-direction |
This line specifies the name of the file from which the x-direction |
914 |
surface wind stress is read. This file is also a two-dimensional |
(zonal) surface wind stress is read. This file is also a two-dimensional |
915 |
($x,y$) map and is enumerated and formatted in the same manner as the |
($x,y$) map and is enumerated and formatted in the same manner as the |
916 |
bathymetry file. The matlab program {\it input/gendata.m} includes example |
bathymetry file. The matlab program {\it input/gendata.m} includes example |
917 |
code to generate a valid |
code to generate a valid |
928 |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
\begin{rawhtml} <A href=../../../code_reference/vdb/code/94.htm> \end{rawhtml} |
929 |
INI\_PARMS |
INI\_PARMS |
930 |
\begin{rawhtml} </A>\end{rawhtml} |
\begin{rawhtml} </A>\end{rawhtml} |
931 |
}. |
}. The wind-stress file is read in the routine |
932 |
|
{\it EXTERNAL\_FIELDS\_LOAD}. |
933 |
|
|
934 |
\fbox{ |
\fbox{ |
935 |
\begin{minipage}{5.0in} |
\begin{minipage}{5.0in} |
944 |
|
|
945 |
\end{itemize} |
\end{itemize} |
946 |
|
|
947 |
\noindent other lines in the file {\it input/data} are standard values |
\noindent other lines in the file {\it input/data} are standard values. |
|
that are described in the MITgcm Getting Started and MITgcm Parameters |
|
|
notes. |
|
948 |
|
|
949 |
\begin{rawhtml}<PRE>\end{rawhtml} |
\begin{rawhtml}<PRE>\end{rawhtml} |
950 |
\begin{small} |
\begin{small} |
953 |
\begin{rawhtml}</PRE>\end{rawhtml} |
\begin{rawhtml}</PRE>\end{rawhtml} |
954 |
|
|
955 |
\subsubsection{File {\it input/data.pkg}} |
\subsubsection{File {\it input/data.pkg}} |
956 |
|
\label{www:tutorials} |
957 |
|
|
958 |
This file uses standard default values and does not contain |
This file uses standard default values and does not contain |
959 |
customisations for this experiment. |
customisations for this experiment. |
960 |
|
|
961 |
\subsubsection{File {\it input/eedata}} |
\subsubsection{File {\it input/eedata}} |
962 |
|
\label{www:tutorials} |
963 |
|
|
964 |
This file uses standard default values and does not contain |
This file uses standard default values and does not contain |
965 |
customisations for this experiment. |
customisations for this experiment. |
966 |
|
|
967 |
\subsubsection{File {\it input/windx.sin\_y}} |
\subsubsection{File {\it input/windx.sin\_y}} |
968 |
|
\label{www:tutorials} |
969 |
|
|
970 |
The {\it input/windx.sin\_y} file specifies a two-dimensional ($x,y$) |
The {\it input/windx.sin\_y} file specifies a two-dimensional ($x,y$) |
971 |
map of wind stress ,$\tau_{x}$, values. The units used are $Nm^{-2}$. |
map of wind stress ,$\tau_{x}$, values. The units used are $Nm^{-2}$ (the |
972 |
Although $\tau_{x}$ is only a function of $y$n in this experiment |
default for MITgcm). |
973 |
|
Although $\tau_{x}$ is only a function of latitude, $y$, |
974 |
|
in this experiment |
975 |
this file must still define a complete two-dimensional map in order |
this file must still define a complete two-dimensional map in order |
976 |
to be compatible with the standard code for loading forcing fields |
to be compatible with the standard code for loading forcing fields |
977 |
in MITgcm. The included matlab program {\it input/gendata.m} gives a complete |
in MITgcm (routine {\it EXTERNAL\_FIELDS\_LOAD}. |
978 |
|
The included matlab program {\it input/gendata.m} gives a complete |
979 |
code for creating the {\it input/windx.sin\_y} file. |
code for creating the {\it input/windx.sin\_y} file. |
980 |
|
|
981 |
\subsubsection{File {\it input/topog.box}} |
\subsubsection{File {\it input/topog.box}} |
982 |
|
\label{www:tutorials} |
983 |
|
|
984 |
|
|
985 |
The {\it input/topog.box} file specifies a two-dimensional ($x,y$) |
The {\it input/topog.box} file specifies a two-dimensional ($x,y$) |
986 |
map of depth values. For this experiment values are either |
map of depth values. For this experiment values are either |
987 |
$0m$ or $-2000\,{\rm m}$, corresponding respectively to a wall or to deep |
$0~{\rm m}$ or $-2000\,{\rm m}$, corresponding respectively to a wall or to deep |
988 |
ocean. The file contains a raw binary stream of data that is enumerated |
ocean. The file contains a raw binary stream of data that is enumerated |
989 |
in the same way as standard MITgcm two-dimensional, horizontal arrays. |
in the same way as standard MITgcm two-dimensional, horizontal arrays. |
990 |
The included matlab program {\it input/gendata.m} gives a complete |
The included matlab program {\it input/gendata.m} gives a complete |
991 |
code for creating the {\it input/topog.box} file. |
code for creating the {\it input/topog.box} file. |
992 |
|
|
993 |
\subsubsection{File {\it code/SIZE.h}} |
\subsubsection{File {\it code/SIZE.h}} |
994 |
|
\label{www:tutorials} |
995 |
|
|
996 |
Two lines are customized in this file for the current experiment |
Two lines are customized in this file for the current experiment |
997 |
|
|
1018 |
\end{small} |
\end{small} |
1019 |
|
|
1020 |
\subsubsection{File {\it code/CPP\_OPTIONS.h}} |
\subsubsection{File {\it code/CPP\_OPTIONS.h}} |
1021 |
|
\label{www:tutorials} |
1022 |
|
|
1023 |
This file uses standard default values and does not contain |
This file uses standard default values and does not contain |
1024 |
customisations for this experiment. |
customisations for this experiment. |
1025 |
|
|
1026 |
|
|
1027 |
\subsubsection{File {\it code/CPP\_EEOPTIONS.h}} |
\subsubsection{File {\it code/CPP\_EEOPTIONS.h}} |
1028 |
|
\label{www:tutorials} |
1029 |
|
|
1030 |
This file uses standard default values and does not contain |
This file uses standard default values and does not contain |
1031 |
customisations for this experiment. |
customisations for this experiment. |
1032 |
|
|
1033 |
\subsubsection{Other Files } |
\subsubsection{Other Files } |
1034 |
|
\label{www:tutorials} |
1035 |
|
|
1036 |
Other files relevant to this experiment are |
Other files relevant to this experiment are |
1037 |
\begin{itemize} |
\begin{itemize} |
1044 |
\end{itemize} |
\end{itemize} |
1045 |
|
|
1046 |
\subsection{Running The Example} |
\subsection{Running The Example} |
1047 |
|
\label{www:tutorials} |
1048 |
\label{SEC:running_the_example} |
\label{SEC:running_the_example} |
1049 |
|
|
1050 |
\subsubsection{Code Download} |
\subsubsection{Code Download} |
1051 |
|
\label{www:tutorials} |
1052 |
|
|
1053 |
In order to run the examples you must first download the code distribution. |
In order to run the examples you must first download the code distribution. |
1054 |
Instructions for downloading the code can be found in the Getting Started |
Instructions for downloading the code can be found in section |
1055 |
Guide \cite{MITgcm_Getting_Started}. |
\ref{sect:obtainingCode}. |
1056 |
|
|
1057 |
\subsubsection{Experiment Location} |
\subsubsection{Experiment Location} |
1058 |
|
\label{www:tutorials} |
1059 |
|
|
1060 |
This example experiments is located under the release sub-directory |
This example experiments is located under the release sub-directory |
1061 |
|
|
1062 |
\vspace{5mm} |
\vspace{5mm} |
1063 |
{\it verification/exp1/ } |
{\it verification/exp2/ } |
1064 |
|
|
1065 |
\subsubsection{Running the Experiment} |
\subsubsection{Running the Experiment} |
1066 |
|
\label{www:tutorials} |
1067 |
|
|
1068 |
To run the experiment |
To run the experiment |
1069 |
|
|
1080 |
% pwd |
% pwd |
1081 |
\end{verbatim} |
\end{verbatim} |
1082 |
|
|
1083 |
You shold see a response on the screen ending in |
You should see a response on the screen ending in |
1084 |
|
|
1085 |
{\it verification/exp1/input } |
{\it verification/exp2/input } |
1086 |
|
|
1087 |
|
|
1088 |
\item Run the genmake script to create the experiment {\it Makefile} |
\item Run the genmake script to create the experiment {\it Makefile} |