--- manual/s_examples/baroclinic_gyre/fourlayer.tex 2001/09/27 00:58:17 1.2 +++ manual/s_examples/baroclinic_gyre/fourlayer.tex 2003/09/15 19:39:04 1.16 @@ -1,7 +1,9 @@ -% $Header: /home/ubuntu/mnt/e9_copy/manual/s_examples/baroclinic_gyre/fourlayer.tex,v 1.2 2001/09/27 00:58:17 cnh Exp $ +% $Header: /home/ubuntu/mnt/e9_copy/manual/s_examples/baroclinic_gyre/fourlayer.tex,v 1.16 2003/09/15 19:39:04 edhill Exp $ % $Name: $ -\section{Example: Four layer Baroclinic Ocean Gyre In Spherical Coordinates} +\section{Four Layer Baroclinic Ocean Gyre In Spherical Coordinates} +\label{www:tutorials} +\label{sect:eg-fourlayer} \bodytext{bgcolor="#FFFFFFFF"} @@ -15,19 +17,21 @@ %{\large May 2001} %\end{center} -\subsection{Introduction} - -This document describes the second example MITgcm experiment. The first -example experiment ilustrated how to configure the code for a single layer -simulation in a cartesian grid. In this example a similar physical problem +This document describes an example experiment using MITgcm +to simulate a baroclinic ocean gyre in spherical +polar coordinates. The barotropic +example experiment in section \ref{sect:eg-baro} +illustrated how to configure the code for a single layer +simulation in a Cartesian grid. In this example a similar physical problem is simulated, but the code is now configured for four layers and in a spherical polar coordinate system. \subsection{Overview} +\label{www:tutorials} This example experiment demonstrates using the MITgcm to simulate a baroclinic, wind-forced, ocean gyre circulation. The experiment -is a numerical rendition of the gyre circulation problem simliar +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}. \\ @@ -35,14 +39,14 @@ In this experiment the model is configured to represent a mid-latitude enclosed sector of fluid on a sphere, $60^{\circ} \times 60^{\circ}$ in lateral extent. The fluid is $2$~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 simulated +by a constant in time zonal wind stress, $\tau_{\lambda}$, that varies +sinusoidally in the north-south direction. Topologically the simulated domain is a sector on a sphere and the coriolis parameter, $f$, is defined -according to latitude, $\phi$ +according to latitude, $\varphi$ \begin{equation} -\label{EQ:fcori} -f(\phi) = 2 \Omega \sin( \phi ) +\label{EQ:eg-fourlayer-fcori} +f(\varphi) = 2 \Omega \sin( \varphi ) \end{equation} \noindent with the rotation rate, $\Omega$ set to $\frac{2 \pi}{86400s}$. @@ -52,20 +56,22 @@ \begin{equation} \label{EQ:taux} -\tau_x(\phi) = \tau_{0}\sin(\pi \frac{\phi}{L_{\phi}}) +\tau_{\lambda}(\varphi) = \tau_{0}\sin(\pi \frac{\varphi}{L_{\varphi}}) \end{equation} -\noindent where $L_{\phi}$ is the lateral domain extent ($60^{\circ}$) and +\noindent where $L_{\varphi}$ is the lateral domain extent ($60^{\circ}$) and $\tau_0$ is set to $0.1N m^{-2}$. \\ -Figure \ref{FIG:simulation_config} -summarises the configuration simulated. -In contrast to example (1) \cite{baro_gyre_case_study}, the current -experiment simulates a spherical polar domain. However, as indicated +Figure \ref{FIG:eg-fourlayer-simulation_config} +summarizes the configuration simulated. +In contrast to the example in section \ref{sect:eg-baro}, the +current experiment simulates a spherical polar domain. As indicated by the axes in the lower left of the figure the model code works internally -in a locally orthoganal coordinate $(x,y,z)$. In the remainder of this -document the local coordinate $(x,y,z)$ will be adopted. +in a locally orthogonal coordinate $(x,y,z)$. For this experiment description +the local orthogonal model coordinate $(x,y,z)$ is synonymous +with the coordinates $(\lambda,\varphi,r)$ shown in figure +\ref{fig:spherical-polar-coord} \\ The experiment has four levels in the vertical, each of equal thickness, @@ -78,20 +84,20 @@ linear \begin{equation} -\label{EQ:linear1_eos} +\label{EQ:eg-fourlayer-linear1_eos} \rho = \rho_{0} ( 1 - \alpha_{\theta}\theta^{'} ) \end{equation} \noindent which is implemented in the model as a density anomaly equation \begin{equation} -\label{EQ:linear1_eos_pert} +\label{EQ:eg-fourlayer-linear1_eos_pert} \rho^{'} = -\rho_{0}\alpha_{\theta}\theta^{'} \end{equation} \noindent with $\rho_{0}=999.8\,{\rm kg\,m}^{-3}$ and $\alpha_{\theta}=2\times10^{-4}\,{\rm degrees}^{-1} $. Integrated forward in -this configuration the model state variable {\bf theta} is synonomous with +this configuration the model state variable {\bf theta} is equivalent to either in-situ temperature, $T$, or potential temperature, $\theta$. For consistency with later examples, in which the equation of state is non-linear, we use $\theta$ to represent temperature here. This is @@ -106,103 +112,194 @@ \caption{Schematic of simulation domain and wind-stress forcing function for the four-layer gyre numerical experiment. The domain is enclosed by solid walls at $0^{\circ}$~E, $60^{\circ}$~E, $0^{\circ}$~N and $60^{\circ}$~N. -In the four-layer case an initial temperature stratification is +An initial stratification is imposed by setting the potential temperature, $\theta$, in each layer. The vertical spacing, $\Delta z$, is constant and equal to $500$m. } -\label{FIG:simulation_config} +\label{FIG:eg-fourlayer-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 latitude and longitude - $\Delta x=\Delta y=1^{\circ}$, so -that there are sixty grid cells in the $x$ and $y$ directions. Vertically the -model is configured with a four layers with constant depth, -$\Delta z$, of $500$~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 -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 +\subsection{Equations solved} +\label{www:tutorials} +For this problem +the implicit free surface, {\bf HPE} (see section \ref{sect:hydrostatic_and_quasi-hydrostatic_forms}) form of the +equations described in Marshall et. al \cite{marshall:97a} are +employed. The flow is three-dimensional with just temperature, $\theta$, as +an active tracer. The equation of state is linear. +A horizontal Laplacian operator $\nabla_{h}^2$ provides viscous +dissipation and provides a diffusive sub-grid scale closure for the +temperature equation. A wind-stress momentum forcing is added to the momentum +equation for the zonal flow, $u$. Other terms in the model +are explicitly switched off for this experiment configuration (see section +\ref{SEC:eg_fourl_code_config} ). This yields an active set of equations +solved in this configuration, written in spherical polar coordinates as +follows \begin{eqnarray} -\label{EQ:model_equations} +\label{EQ:eg-fourlayer-model_equations} \frac{Du}{Dt} - fv + - \frac{1}{\rho}\frac{\partial p^{'}}{\partial x} - + \frac{1}{\rho}\frac{\partial p^{\prime}}{\partial \lambda} - A_{h}\nabla_{h}^2u - A_{z}\frac{\partial^{2}u}{\partial z^{2}} & = & -\cal{F} +\cal{F}_{\lambda} \\ \frac{Dv}{Dt} + fu + - \frac{1}{\rho}\frac{\partial p^{'}}{\partial y} - + \frac{1}{\rho}\frac{\partial p^{\prime}}{\partial \varphi} - A_{h}\nabla_{h}^2v - A_{z}\frac{\partial^{2}v}{\partial z^{2}} & = & 0 \\ -\frac{\partial \eta}{\partial t} + \nabla_{h}\cdot \vec{u} +\frac{\partial \eta}{\partial t} + \frac{\partial H \widehat{u}}{\partial \lambda} + +\frac{\partial H \widehat{v}}{\partial \varphi} &=& 0 +\label{eq:fourl_example_continuity} \\ \frac{D\theta}{Dt} - K_{h}\nabla_{h}^2\theta - K_{z}\frac{\partial^{2}\theta}{\partial z^{2}} & = & 0 +\label{eq:eg_fourl_theta} +\\ +p^{\prime} & = & +g\rho_{0} \eta + \int^{0}_{-z}\rho^{\prime} dz \\ -g\rho_{0} \eta + \int^{0}_{-z}\rho^{'} dz & = & p^{'} +\rho^{\prime} & = &- \alpha_{\theta}\rho_{0}\theta^{\prime} \\ -{\cal F} |_{s} & = & \frac{\tau_{x}}{\rho_{0}\Delta z_{s}} +{\cal F}_{\lambda} |_{s} & = & \frac{\tau_{\lambda}}{\rho_{0}\Delta z_{s}} \\ -{\cal F} |_{i} & = & 0 +{\cal F}_{\lambda} |_{i} & = & 0 \end{eqnarray} -\noindent where $u$ and $v$ are the $x$ and $y$ components of the -flow vector $\vec{u}$. The suffices ${s},{i}$ indicate surface and -interior model levels respectively. As described in -MITgcm Numerical Solution Procedure \cite{MITgcm_Numerical_Scheme}, the time -evolution of potential temperature, $\theta$, equation is solved prognostically. -The total pressure, $p$, is diagnosed by summing pressure due to surface -elevation $\eta$ and the hydrostatic pressure. -\\ +\noindent where $u$ and $v$ are the components of the horizontal +flow vector $\vec{u}$ on the sphere ($u=\dot{\lambda},v=\dot{\varphi}$). +The terms $H\widehat{u}$ and $H\widehat{v}$ are the components of the vertical +integral term given in equation \ref{eq:free-surface} and +explained in more detail in section \ref{sect:pressure-method-linear-backward}. +However, for the problem presented here, the continuity relation (equation +\ref{eq:fourl_example_continuity}) differs from the general form given +in section \ref{sect:pressure-method-linear-backward}, +equation \ref{eq:linear-free-surface=P-E+R}, because the source terms +${\cal P}-{\cal E}+{\cal R}$ +are all $0$. + +The pressure field, $p^{\prime}$, is separated into a barotropic part +due to variations in sea-surface height, $\eta$, and a hydrostatic +part due to variations in density, $\rho^{\prime}$, integrated +through the water column. + +The suffices ${s},{i}$ indicate surface layer and the interior of the domain. +The windstress forcing, ${\cal F}_{\lambda}$, is applied in the surface layer +by a source term in the zonal momentum equation. In the ocean interior +this term is zero. + +In the momentum equations +lateral and vertical boundary conditions for the $\nabla_{h}^{2}$ +and $\frac{\partial^{2}}{\partial z^{2}}$ operators are specified +when the numerical simulation is run - see section +\ref{SEC:eg_fourl_code_config}. For temperature +the boundary condition is ``zero-flux'' +e.g. $\frac{\partial \theta}{\partial \varphi}= +\frac{\partial \theta}{\partial \lambda}=\frac{\partial \theta}{\partial z}=0$. + + + +\subsection{Discrete Numerical Configuration} +\label{www:tutorials} + + The domain is discretised with +a uniform grid spacing in latitude and longitude + $\Delta \lambda=\Delta \varphi=1^{\circ}$, so +that there are sixty grid cells in the zonal and meridional directions. +Vertically the +model is configured with four layers with constant depth, +$\Delta z$, of $500$~m. The internal, locally orthogonal, model coordinate +variables $x$ and $y$ are initialized from the values of +$\lambda$, $\varphi$, $\Delta \lambda$ and $\Delta \varphi$ in +radians according to + +\begin{eqnarray} +x=r\cos(\varphi)\lambda,~\Delta x & = &r\cos(\varphi)\Delta \lambda \\ +y=r\varphi,~\Delta y &= &r\Delta \varphi +\end{eqnarray} + +The procedure for generating a set of internal grid variables from a +spherical polar grid specification is discussed in section +\ref{sect:spatial_discrete_horizontal_grid}. + +\noindent\fbox{ \begin{minipage}{5.5in} +{\em S/R INI\_SPHERICAL\_POLAR\_GRID} ({\em +model/src/ini\_spherical\_polar\_grid.F}) + +$A_c$, $A_\zeta$, $A_w$, $A_s$: {\bf rAc}, {\bf rAz}, {\bf rAw}, {\bf rAs} +({\em GRID.h}) + +$\Delta x_g$, $\Delta y_g$: {\bf DXg}, {\bf DYg} ({\em GRID.h}) + +$\Delta x_c$, $\Delta y_c$: {\bf DXc}, {\bf DYc} ({\em GRID.h}) + +$\Delta x_f$, $\Delta y_f$: {\bf DXf}, {\bf DYf} ({\em GRID.h}) + +$\Delta x_v$, $\Delta y_u$: {\bf DXv}, {\bf DYu} ({\em GRID.h}) + +\end{minipage} }\\ + + + +As described in \ref{sect:tracer_equations}, the time evolution of potential +temperature, +$\theta$, (equation \ref{eq:eg_fourl_theta}) +is evaluated prognostically. The centered second-order scheme with +Adams-Bashforth time stepping described in section +\ref{sect:tracer_equations_abII} is used to step forward the temperature +equation. Prognostic terms in +the momentum equations are solved using flux form as +described in section \ref{sect:flux-form_momentum_eqautions}. +The pressure forces that drive the fluid motions, ( +$\frac{\partial p^{'}}{\partial \lambda}$ and $\frac{\partial p^{'}}{\partial \varphi}$), are found by summing pressure due to surface +elevation $\eta$ and the hydrostatic pressure. The hydrostatic part of the +pressure is diagnosed explicitly by integrating density. The sea-surface +height, $\eta$, is diagnosed using an implicit scheme. The pressure +field solution method is described in sections +\ref{sect:pressure-method-linear-backward} and +\ref{sect:finding_the_pressure_field}. \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 viscosity coefficient, $A_{h}$, is set to $400 m s^{-1}$. +This value is chosen to yield a Munk layer width, \begin{eqnarray} -\label{EQ:munk_layer} +\label{EQ:eg-fourlayer-munk_layer} M_{w} = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}} \end{eqnarray} \noindent of $\approx 100$km. This is greater than the model -resolution in mid-latitudes $\Delta x$, ensuring that the frictional +resolution in mid-latitudes +$\Delta x=r \cos(\varphi) \Delta \lambda \approx 80~{\rm km}$ at +$\varphi=45^{\circ}$, ensuring that the frictional boundary layer is well resolved. \\ \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 \begin{eqnarray} -\label{EQ:laplacian_stability} +\label{EQ:eg-fourlayer-laplacian_stability} S_{l} = 4 \frac{A_{h} \delta t}{{\Delta x}^2} \end{eqnarray} \noindent evaluates to 0.012, which is well below the 0.3 upper limit -for stability. +for stability for this term under ABII time-stepping. \\ \noindent The vertical dissipation coefficient, $A_{z}$, is set to $1\times10^{-2} {\rm m}^2{\rm s}^{-1}$. The associated stability limit \begin{eqnarray} -\label{EQ:laplacian_stability_z} +\label{EQ:eg-fourlayer-laplacian_stability_z} S_{l} = 4 \frac{A_{z} \delta t}{{\Delta z}^2} \end{eqnarray} @@ -213,10 +310,9 @@ \\ \noindent The numerical stability for inertial oscillations -\cite{Adcroft_thesis} \begin{eqnarray} -\label{EQ:inertial_stability} +\label{EQ:eg-fourlayer-inertial_stability} S_{i} = f^{2} {\delta t}^2 \end{eqnarray} @@ -224,35 +320,36 @@ limit for stability. \\ -\noindent The advective CFL \cite{Adcroft_thesis} for a extreme maximum +\noindent The advective CFL for a extreme maximum horizontal flow speed of $ | \vec{u} | = 2 ms^{-1}$ \begin{eqnarray} -\label{EQ:cfl_stability} -S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} +\label{EQ:eg-fourlayer-cfl_stability} +C_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} \end{eqnarray} \noindent evaluates to $5 \times 10^{-2}$. This is well below the stability limit of 0.5. \\ -\noindent The stability parameter for internal gravity waves -\cite{Adcroft_thesis} +\noindent The stability parameter for internal gravity waves +propagating at $2~{\rm m}~{\rm s}^{-1}$ \begin{eqnarray} -\label{EQ:igw_stability} +\label{EQ:eg-fourlayer-igw_stability} S_{c} = \frac{c_{g} \delta t}{ \Delta x} \end{eqnarray} -\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 stability limit of 0.25. \subsection{Code Configuration} -\label{SEC:code_config} +\label{www:tutorials} +\label{SEC:eg_fourl_code_config} The model configuration for this experiment resides under the -directory {\it verification/exp1/}. The experiment files +directory {\it verification/exp2/}. The experiment files \begin{itemize} \item {\it input/data} \item {\it input/data.pkg} @@ -263,11 +360,12 @@ \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 -to these files associated with this experiment. +contain the code customisations and parameter settings for this +experiment. Below we describe the customisations 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 @@ -277,571 +375,306 @@ \item Line 4, \begin{verbatim} tRef=20.,10.,8.,6., \end{verbatim} -this line sets -the initial and reference values of potential temperature at each model -level in units of $^{\circ}$C. -The entries are ordered from surface to depth. For each -depth level the inital and reference profiles will be uniform in -$x$ and $y$. The values specified here are read into the -variable -{\bf -\begin{rawhtml} \end{rawhtml} -tRef -\begin{rawhtml} \end{rawhtml} -} -in the model code, by procedure -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -%% \codelink{var:tref} tRef \endlink -%% \codelink{file:ini_parms} {\it INI\_PARMS } \endlink -%% \codelink{proc:ini_parms} {\it INI\_PARMS } \endlink -%% \var{tref} -%% \proc{ini_parms} -%% \file{ini_parms} -\newcommand{\VARtref}{ -{\bf -\begin{rawhtml} \end{rawhtml} -tRef -\begin{rawhtml} \end{rawhtml} -} -} - - +this line sets the initial and reference values of potential +temperature at each model level in units of $^{\circ}$C. The entries +are ordered from surface to depth. For each depth level the initial +and reference profiles will be uniform in $x$ and $y$. The values +specified here are read into the variable \varlink{tRef}{tRef} in the +model code, by procedure \filelink{INI\_PARMS}{model-src-ini_parms.F} \fbox{ -\begin{minipage}{5.0in} -{\it S/R INI\_THETA} -({\it ini\_theta.F}) -\end{minipage} + \begin{minipage}{5.0in} + {\it S/R INI\_THETA}({\it ini\_theta.F}) + \end{minipage} } -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} - +\filelink{ini\_theta.F}{model-src-ini_theta.F} \item Line 6, \begin{verbatim} viscAz=1.E-2, \end{verbatim} -this line sets the vertical laplacian dissipation coefficient to -$1 \times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary conditions -for this operator are specified later. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -viscAz -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -} -and is copied into model general vertical coordinate variable -{\bf -\begin{rawhtml} \end{rawhtml} -viscAr -\begin{rawhtml} \end{rawhtml} -}. +this line sets the vertical Laplacian dissipation coefficient to $1 +\times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary conditions for this +operator are specified later. The variable \varlink{viscAz}{viscAz} +is read in the routine \filelink{ini\_parms.F}{model-src-ini_parms.F} +and is copied into model general vertical coordinate variable +\varlink{viscAr}{viscAr} At each time step, the viscous term +contribution to the momentum equations is calculated in routine +\varlink{CALC\_DIFFUSIVITY}{CALC_DIFFUSIVITY} \fbox{ \begin{minipage}{5.0in} {\it S/R CALC\_DIFFUSIVITY}({\it calc\_diffusivity.F}) \end{minipage} } -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} \item Line 7, \begin{verbatim} viscAh=4.E2, \end{verbatim} -this line sets the horizontal laplacian frictional dissipation coefficient to -$1 \times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary conditions -for this operator are specified later. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -viscAh -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. + this line sets the horizontal laplacian frictional dissipation + coefficient to $1 \times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary + conditions for this operator are specified later. The variable + \varlink{viscAh}{viscAh} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS} and applied in routines + \varlink{CALC\_MOM\_RHS}{CALC_MOM_RHS} and + \varlink{CALC\_GW}{CALC_GW}. \fbox{ -\begin{minipage}{5.0in} -{\it S/R CALC\_MOM\_RHS}({\it calc\_mom\_rhs.F}) -\end{minipage} + \begin{minipage}{5.0in} + {\it S/R CALC\_MOM\_RHS}({\it calc\_mom\_rhs.F}) + \end{minipage} } -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} - \fbox{ -\begin{minipage}{5.0in} -{\it S/R CALC\_GW}({\it calc\_gw.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} + \begin{minipage}{5.0in} + {\it S/R CALC\_GW}({\it calc\_gw.F}) + \end{minipage} } -\item Lines 8, +\item Line 8, \begin{verbatim} no_slip_sides=.FALSE. \end{verbatim} -this line selects a free-slip lateral boundary condition for -the horizontal laplacian friction operator -e.g. $\frac{\partial u}{\partial y}$=0 along boundaries in $y$ and -$\frac{\partial v}{\partial x}$=0 along boundaries in $x$. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -no\_slip\_sides -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R CALC\_MOM\_RHS}({\it calc\_mom\_rhs.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} - + this line selects a free-slip lateral boundary condition for the + horizontal laplacian friction operator e.g. $\frac{\partial + u}{\partial y}$=0 along boundaries in $y$ and $\frac{\partial + v}{\partial x}$=0 along boundaries in $x$. The variable + \varlink{no\_slip\_sides}{no_slip_sides} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS} and the boundary condition is + evaluated in routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R CALC\_MOM\_RHS}({\it calc\_mom\_rhs.F}) + \end{minipage} + } + \filelink{calc\_mom\_rhs.F}{calc_mom_rhs.F} + \item Lines 9, \begin{verbatim} no_slip_bottom=.TRUE. \end{verbatim} -this line selects a no-slip boundary condition for bottom -boundary condition in the vertical laplacian friction operator -e.g. $u=v=0$ at $z=-H$, where $H$ is the local depth of the domain. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -no\_slip\_bottom -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R CALC\_MOM\_RHS}({\it calc\_mom\_rhs.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + this line selects a no-slip boundary condition for bottom boundary + condition in the vertical laplacian friction operator e.g. $u=v=0$ + at $z=-H$, where $H$ is the local depth of the domain. The variable + \varlink{no\_slip\_bottom}{no\_slip\_bottom} is read in the routine + \filelink{INI\_PARMS}{model-src-ini_parms.F} and is applied in the + routine \varlink{CALC\_MOM\_RHS}{CALC_MOM_RHS}. + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R CALC\_MOM\_RHS}({\it calc\_mom\_rhs.F}) + \end{minipage} + } + \filelink{calc\_mom\_rhs.F}{calc_mom_rhs.F} \item Line 10, \begin{verbatim} diffKhT=4.E2, \end{verbatim} -this line sets the horizontal diffusion coefficient for temperature -to $400\,{\rm m^{2}s^{-1}}$. The boundary condition on this -operator is $\frac{\partial}{\partial x}=\frac{\partial}{\partial y}=0$ at -all boundaries. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -diffKhT -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ \begin{minipage}{5.0in} -{\it S/R CALC\_GT}({\it calc\_gt.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + this line sets the horizontal diffusion coefficient for temperature + to $400\,{\rm m^{2}s^{-1}}$. The boundary condition on this operator + is $\frac{\partial}{\partial x}=\frac{\partial}{\partial y}=0$ at + all boundaries. The variable \varlink{diffKhT}{diffKhT} is read in + the routine \varlink{INI\_PARMS}{INI_PARMS} and used in routine + \varlink{CALC\_GT}{CALC_GT}. + + \fbox{ \begin{minipage}{5.0in} + {\it S/R CALC\_GT}({\it calc\_gt.F}) + \end{minipage} + } + \filelink{calc\_gt.F}{model-src-calc_gt.F} \item Line 11, \begin{verbatim} diffKzT=1.E-2, \end{verbatim} -this line sets the vertical diffusion coefficient for temperature -to $10^{-2}\,{\rm m^{2}s^{-1}}$. The boundary condition on this -operator is $\frac{\partial}{\partial z}$ = 0 on all boundaries. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -diffKzT -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. -It is copied into model general vertical coordinate variable -{\bf -\begin{rawhtml} \end{rawhtml} -diffKrT -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ \begin{minipage}{5.0in} -{\it S/R CALC\_DIFFUSIVITY}({\it calc\_diffusivity.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} - - + this line sets the vertical diffusion coefficient for temperature to + $10^{-2}\,{\rm m^{2}s^{-1}}$. The boundary condition on this + operator is $\frac{\partial}{\partial z}$ = 0 on all boundaries. + The variable \varlink{diffKzT}{diffKzT} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS}. It is copied into model general + vertical coordinate variable \varlink{diffKrT}{diffKrT} which is + used in routine \varlink{CALC\_DIFFUSIVITY}{CALC_DIFFUSIVITY}. + + \fbox{ \begin{minipage}{5.0in} + {\it S/R CALC\_DIFFUSIVITY}({\it calc\_diffusivity.F}) + \end{minipage} + } + \filelink{calc\_diffusivity.F}{model-src-calc_diffusivity.F} \item Line 13, \begin{verbatim} tAlpha=2.E-4, \end{verbatim} -This line sets the thermal expansion coefficient for the fluid -to $2 \times 10^{-4}\,{\rm degrees}^{-1}$ -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -tAlpha -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R FIND\_RHO}({\it find\_rho.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + This line sets the thermal expansion coefficient for the fluid to $2 + \times 10^{-4}\,{\rm degrees}^{-1}$ The variable + \varlink{tAlpha}{tAlpha} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS}. The routine + \varlink{FIND\_RHO}{FIND\_RHO} makes use of {\bf tAlpha}. + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R FIND\_RHO}({\it find\_rho.F}) + \end{minipage} + } + \filelink{find\_rho.F}{model-src-find_rho.F} \item Line 18, \begin{verbatim} eosType='LINEAR' \end{verbatim} -This line selects the linear form of the equation of state. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -eosType -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R FIND\_RHO}({\it find\_rho.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} - - + This line selects the linear form of the equation of state. The + variable \varlink{eosType}{eosType} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS}. The values of {\bf eosType} sets + which formula in routine {\it FIND\_RHO} is used to calculate + density. + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R FIND\_RHO}({\it find\_rho.F}) + \end{minipage} + } + \filelink{find\_rho.F}{model-src-find_rho.F} \item Line 40, \begin{verbatim} usingSphericalPolarGrid=.TRUE., \end{verbatim} -This line requests that the simulation be performed in a -spherical polar coordinate system. It affects the interpretation of -grid inoput parameters, for exampl {\bf delX} and {\bf delY} and -causes the grid generation routines to initialise an internal grid based -on spherical polar geometry. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -usingSphericalPolarGrid -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + This line requests that the simulation be performed in a spherical + polar coordinate system. It affects the interpretation of grid input + parameters, for example {\bf delX} and {\bf delY} and causes the + grid generation routines to initialize an internal grid based on + spherical polar geometry. The variable + \varlink{usingSphericalPolarGrid}{usingSphericalPolarGrid} is read + in the routine \varlink{INI\_PARMS}{INI_PARMS}. When set to {\bf + .TRUE.} the settings of {\bf delX} and {\bf delY} are taken to be + in degrees. These values are used in the routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) + \end{minipage} + } + \filelink{ini\_spherical\_polar\_grid.F}{model-src-ini_spherical_polar_grid.F} \item Line 41, \begin{verbatim} phiMin=0., \end{verbatim} -This line sets the southern boundary of the modeled -domain to $0^{\circ}$ latitude. This value affects both the -generation of the locally orthogonal grid that the model -uses internally and affects the initialisation of the coriolis force. -Note - it is not required to set -a longitude boundary, since the absolute longitude does -not alter the kernel equation discretisation. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -phiMin -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + This line sets the southern boundary of the modeled domain to + $0^{\circ}$ latitude. This value affects both the generation of the + locally orthogonal grid that the model uses internally and affects + the initialization of the coriolis force. Note - it is not required + to set a longitude boundary, since the absolute longitude does not + alter the kernel equation discretisation. The variable + \varlink{phiMin}{phiMin} is read in the + routine \varlink{INI\_PARMS}{INI_PARMS} and is used in routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) + \end{minipage} + } + \filelink{ini\_spherical\_polar\_grid.F}{model-src-ini_spherical_polar_grid.F} \item Line 42, \begin{verbatim} delX=60*1., \end{verbatim} -This line sets the horizontal grid spacing between each y-coordinate line -in the discrete grid to $1^{\circ}$ in longitude. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -delX -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + This line sets the horizontal grid spacing between each y-coordinate + line in the discrete grid to $1^{\circ}$ in longitude. The variable + \varlink{delX}{delX} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS} and is used in routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) + \end{minipage} + } + \filelink{ini\_spherical\_polar\_grid.F}{model-src-ini_spherical_polar_grid.F} \item Line 43, \begin{verbatim} delY=60*1., \end{verbatim} -This line sets the horizontal grid spacing between each y-coordinate line -in the discrete grid to $1^{\circ}$ in latitude. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -delY -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + This line sets the horizontal grid spacing between each y-coordinate + line in the discrete grid to $1^{\circ}$ in latitude. The variable + \varlink{delY}{delY} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS} and is used in routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) + \end{minipage} + } + \filelink{ini\_spherical\_polar\_grid.F}{model-src-ini_spherical_polar_grid.F} \item Line 44, \begin{verbatim} delZ=500.,500.,500.,500., \end{verbatim} -This line sets the vertical grid spacing between each z-coordinate line -in the discrete grid to $500\,{\rm m}$, so that the total model depth -is $2\,{\rm km}$. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -delZ -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. -It is copied into the internal -model coordinate variable -{\bf -\begin{rawhtml} \end{rawhtml} -delR -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R INI\_VERTICAL\_GRID}({\it ini\_vertical\_grid.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + This line sets the vertical grid spacing between each z-coordinate + line in the discrete grid to $500\,{\rm m}$, so that the total model + depth is $2\,{\rm km}$. The variable \varlink{delZ}{delZ} is read + in the routine \varlink{INI\_PARMS}{INI_PARMS}. It is copied into + the internal model coordinate variable \varlink{delR}{delR} which is + used in routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R INI\_VERTICAL\_GRID}({\it ini\_vertical\_grid.F}) + \end{minipage} + } + \filelink{ini\_vertical\_grid.F}{model-src-ini_vertical_grid.F} \item Line 47, \begin{verbatim} bathyFile='topog.box' \end{verbatim} -This line specifies the name of the file from which the domain -bathymetry is read. This file is a two-dimensional ($x,y$) map of -depths. This file is assumed to contain 64-bit binary numbers -giving the depth of the model at each grid cell, ordered with the x -coordinate varying fastest. The points are ordered from low coordinate -to high coordinate for both axes. The units and orientation of the -depths in this file are the same as used in the MITgcm code. In this -experiment, a depth of $0m$ indicates a solid wall and a depth -of $-2000m$ indicates open ocean. The matlab program -{\it input/gendata.m} shows an example of how to generate a -bathymetry file. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -bathyFile -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R INI\_DEPTHS}({\it ini\_depths.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} - + This line specifies the name of the file from which the domain + bathymetry is read. This file is a two-dimensional ($x,y$) map of + depths. This file is assumed to contain 64-bit binary numbers giving + the depth of the model at each grid cell, ordered with the x + coordinate varying fastest. The points are ordered from low + coordinate to high coordinate for both axes. The units and + orientation of the depths in this file are the same as used in the + MITgcm code. In this experiment, a depth of $0m$ indicates a solid + wall and a depth of $-2000m$ indicates open ocean. The matlab + program {\it input/gendata.m} shows an example of how to generate a + bathymetry file. The variable \varlink{bathyFile}{bathyFile} is + read in the routine \varlink{INI\_PARMS}{INI_PARMS}. The bathymetry + file is read in the routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R INI\_DEPTHS}({\it ini\_depths.F}) + \end{minipage} + } + \filelink{ini\_depths.F}{model-src-ini_depths.F} \item Line 50, \begin{verbatim} zonalWindFile='windx.sin_y' \end{verbatim} -This line specifies the name of the file from which the x-direction -surface wind stress is read. This file is also a two-dimensional -($x,y$) map and is enumerated and formatted in the same manner as the -bathymetry file. The matlab program {\it input/gendata.m} includes example -code to generate a valid -{\bf zonalWindFile} -file. -The variable -{\bf -\begin{rawhtml} \end{rawhtml} -zonalWindFile -\begin{rawhtml} \end{rawhtml} -} -is read in the routine -{\it -\begin{rawhtml} \end{rawhtml} -INI\_PARMS -\begin{rawhtml} \end{rawhtml} -}. - -\fbox{ -\begin{minipage}{5.0in} -{\it S/R EXTERNAL\_FIELDS\_LOAD}({\it external\_fields\_load.F}) -\end{minipage} -} -{\bf -\begin{rawhtml} \end{rawhtml} -goto code -\begin{rawhtml} \end{rawhtml} -} + This line specifies the name of the file from which the x-direction + (zonal) surface wind stress is read. This file is also a + two-dimensional ($x,y$) map and is enumerated and formatted in the + same manner as the bathymetry file. The matlab program {\it + input/gendata.m} includes example code to generate a valid {\bf + zonalWindFile} file. The variable + \varlink{zonalWindFile}{zonalWindFile} is read in the routine + \varlink{INI\_PARMS}{INI_PARMS}. The wind-stress file is read in + the routine + + \fbox{ + \begin{minipage}{5.0in} + {\it S/R EXTERNAL\_FIELDS\_LOAD}({\it external\_fields\_load.F}) + \end{minipage} + } + \filelink{external\_fields\_load.F}{model-src-external_fields_load.F} \end{itemize} -\noindent other lines in the file {\it input/data} are standard values -that are described in the MITgcm Getting Started and MITgcm Parameters -notes. +\noindent other lines in the file {\it input/data} are standard values. \begin{rawhtml}
\end{rawhtml} \begin{small} @@ -850,37 +683,44 @@ \begin{rawhtml}\end{rawhtml} \subsubsection{File {\it input/data.pkg}} +\label{www:tutorials} This file uses standard default values and does not contain customisations 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. \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 $Nm^{-2}$. -Although $\tau_{x}$ is only a function of $y$n in this experiment -this file must still define a complete two-dimensional map in order -to be compatible with the standard code for loading forcing fields -in MITgcm. The included matlab program {\it input/gendata.m} gives a complete -code for creating the {\it input/windx.sin\_y} file. +The {\it input/windx.sin\_y} file specifies a two-dimensional ($x,y$) +map of wind stress ,$\tau_{x}$, values. The units used are $Nm^{-2}$ +(the default for MITgcm). Although $\tau_{x}$ is only a function of +latitude, $y$, in this experiment this file must still define a +complete two-dimensional map in order to be compatible with the +standard code for loading forcing fields in MITgcm (routine {\it + EXTERNAL\_FIELDS\_LOAD}. The included matlab program {\it + input/gendata.m} gives a complete 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 ($x,y$) map of depth values. For this experiment values are either -$0m$ 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 ocean. The file contains a raw binary stream of data that is enumerated in the same way as standard MITgcm two-dimensional, horizontal arrays. The included matlab program {\it input/gendata.m} gives a complete 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 @@ -907,17 +747,20 @@ \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. \subsubsection{File {\it code/CPP\_EEOPTIONS.h}} +\label{www:tutorials} This file uses standard default values and does not contain customisations for this experiment. \subsubsection{Other Files } +\label{www:tutorials} Other files relevant to this experiment are \begin{itemize} @@ -930,22 +773,26 @@ \end{itemize} \subsection{Running The Example} +\label{www:tutorials} \label{SEC:running_the_example} \subsubsection{Code Download} +\label{www:tutorials} In order to run the examples you must first download the code distribution. -Instructions for downloading the code can be found in the Getting Started -Guide \cite{MITgcm_Getting_Started}. +Instructions for downloading the code can be found in section +\ref{sect:obtainingCode}. \subsubsection{Experiment Location} +\label{www:tutorials} This example experiments is located under the release sub-directory \vspace{5mm} -{\it verification/exp1/ } +{\it verification/exp2/ } \subsubsection{Running the Experiment} +\label{www:tutorials} To run the experiment @@ -962,9 +809,9 @@ % pwd \end{verbatim} - You shold see a response on the screen ending in + You should see a response on the screen ending in -{\it verification/exp1/input } +{\it verification/exp2/input } \item Run the genmake script to create the experiment {\it Makefile}