1 |
adcroft |
1.1 |
% $Header: $ |
2 |
|
|
% $Name: $ |
3 |
|
|
|
4 |
|
|
\section{Example: Centenial Time Scale Sensitivities} |
5 |
|
|
|
6 |
|
|
\bodytext{bgcolor="#FFFFFFFF"} |
7 |
|
|
|
8 |
|
|
%\begin{center} |
9 |
|
|
%{\Large \bf Using MITgcm to Look at Centenial Time Scale |
10 |
|
|
%Sensitivities} |
11 |
|
|
% |
12 |
|
|
%\vspace*{4mm} |
13 |
|
|
% |
14 |
|
|
%\vspace*{3mm} |
15 |
|
|
%{\large May 2001} |
16 |
|
|
%\end{center} |
17 |
|
|
|
18 |
|
|
\subsection{Introduction} |
19 |
|
|
|
20 |
|
|
This document describes the fourth example MITgcm experiment. |
21 |
|
|
This example iilustrates the use of |
22 |
|
|
the MITgcm to perform sentivity analysis in a |
23 |
|
|
large scale ocean circulation simulation. |
24 |
|
|
|
25 |
|
|
\subsection{Overview} |
26 |
|
|
|
27 |
|
|
This example experiment demonstrates using the MITgcm to simulate |
28 |
|
|
the planetary ocean circulation. The simulation is configured |
29 |
|
|
with realistic geography and bathymetry on a |
30 |
|
|
$4^{\circ} \times 4^{\circ}$ spherical polar grid. |
31 |
|
|
Twenty vertical layers are used in the vertical, ranging in thickness |
32 |
|
|
from $50\,{\rm m}$ at the surface to $815\,{\rm m}$ at depth, |
33 |
|
|
giving a maximum model depth of $6\,{\rm km}$. |
34 |
|
|
At this resolution, the configuration |
35 |
|
|
can be integrated forward for thousands of years on a single |
36 |
|
|
processor desktop computer. |
37 |
|
|
\\ |
38 |
|
|
|
39 |
|
|
The model is forced with climatalogical wind stress data and surface |
40 |
|
|
flux data from Da Silva \cite{DaSilva94}. Climatalogical data |
41 |
|
|
from Levitus \cite{Levitus94} is used to initialise the model hydrography. |
42 |
|
|
Levitus data is also used throughout the calculation |
43 |
|
|
to derive air-sea fluxes of heat at the ocean surface. |
44 |
|
|
These fluxes are combined with climatalogical estimates of |
45 |
|
|
surface heat flux and fresh water, resulting in a mixed boundary |
46 |
|
|
condition of the style decribed in Haney \cite{Haney}. |
47 |
|
|
Altogether, this yields the following forcing applied |
48 |
|
|
in the model surface layer. |
49 |
|
|
|
50 |
|
|
\begin{eqnarray} |
51 |
|
|
\label{EQ:global_forcing} |
52 |
|
|
\label{EQ:global_forcing_fu} |
53 |
|
|
{\cal F}_{u} & = & \frac{\tau_{x}}{\rho_{0} \Delta z_{s}} |
54 |
|
|
\\ |
55 |
|
|
\label{EQ:global_forcing_fv} |
56 |
|
|
{\cal F}_{v} & = & \frac{\tau_{y}}{\rho_{0} \Delta z_{s}} |
57 |
|
|
\\ |
58 |
|
|
\label{EQ:global_forcing_ft} |
59 |
|
|
{\cal F}_{\theta} & = & - \lambda_{\theta} ( \theta - \theta^{\ast} ) |
60 |
|
|
- \frac{1}{C_{p} \rho_{0} \Delta z_{s}}{\cal Q} |
61 |
|
|
\\ |
62 |
|
|
\label{EQ:global_forcing_fs} |
63 |
|
|
{\cal F}_{s} & = & - \lambda_{s} ( S - S^{\ast} ) |
64 |
|
|
+ \frac{S_{0}}{\Delta z_{s}}({\cal E} - {\cal P} - {\cal R}) |
65 |
|
|
\end{eqnarray} |
66 |
|
|
|
67 |
|
|
\noindent where ${\cal F}_{u}$, ${\cal F}_{v}$, ${\cal F}_{\theta}$, |
68 |
|
|
${\cal F}_{s}$ are the forcing terms in the zonal and meridional |
69 |
|
|
momentum and in the potential temperature and salinity |
70 |
|
|
equations respectively. |
71 |
|
|
The term $\Delta z_{s}$ represents the top ocean layer thickness. |
72 |
|
|
It is used in conjunction with the reference density, $\rho_{0}$ |
73 |
|
|
(here set to $999.8\,{\rm kg\,m^{-3}}$), the |
74 |
|
|
reference salinity, $S_{0}$ (here set to 35ppt), |
75 |
|
|
and a specific heat capacity $C_{p}$ to convert |
76 |
|
|
wind-stress fluxes given in ${\rm N}\,m^{-2}$, |
77 |
|
|
\\ |
78 |
|
|
|
79 |
|
|
|
80 |
|
|
The configuration is illustrated in figure \ref{simulation_config}. |
81 |
|
|
|
82 |
|
|
|
83 |
|
|
\subsection{Discrete Numerical Configuration} |
84 |
|
|
|
85 |
|
|
|
86 |
|
|
The model is configured in hydrostatic form. The domain is discretised with |
87 |
|
|
a uniform grid spacing in latitude and longitude of |
88 |
|
|
$\Delta x=\Delta y=4^{\circ}$, so |
89 |
|
|
that there are ninety grid cells in the $x$ and forty in the |
90 |
|
|
$y$ direction (Arctic polar regions are not |
91 |
|
|
included in this experiment). Vertically the |
92 |
|
|
model is configured with twenty layers with the following thicknesses |
93 |
|
|
$\Delta z_{1} = 50\,{\rm m},\, |
94 |
|
|
\Delta z_{2} = 50\,{\rm m},\, |
95 |
|
|
\Delta z_{3} = 55\,{\rm m},\, |
96 |
|
|
\Delta z_{4} = 60\,{\rm m},\, |
97 |
|
|
\Delta z_{5} = 65\,{\rm m},\, |
98 |
|
|
$ |
99 |
|
|
$ |
100 |
|
|
\Delta z_{6}~=~70\,{\rm m},\, |
101 |
|
|
\Delta z_{7}~=~80\,{\rm m},\, |
102 |
|
|
\Delta z_{8}~=95\,{\rm m},\, |
103 |
|
|
\Delta z_{9}=120\,{\rm m},\, |
104 |
|
|
\Delta z_{10}=155\,{\rm m},\, |
105 |
|
|
$ |
106 |
|
|
$ |
107 |
|
|
\Delta z_{11}=200\,{\rm m},\, |
108 |
|
|
\Delta z_{12}=260\,{\rm m},\, |
109 |
|
|
\Delta z_{13}=320\,{\rm m},\, |
110 |
|
|
\Delta z_{14}=400\,{\rm m},\, |
111 |
|
|
\Delta z_{15}=480\,{\rm m},\, |
112 |
|
|
$ |
113 |
|
|
$ |
114 |
|
|
\Delta z_{16}=570\,{\rm m},\, |
115 |
|
|
\Delta z_{17}=655\,{\rm m},\, |
116 |
|
|
\Delta z_{18}=725\,{\rm m},\, |
117 |
|
|
\Delta z_{19}=775\,{\rm m},\, |
118 |
|
|
\Delta z_{20}=815\,{\rm m} |
119 |
|
|
$ (here the numeric subscript indicates the model level index number, ${\tt k}$). |
120 |
|
|
The implicit free surface form of the pressure equation described in Marshall et. al |
121 |
|
|
\cite{Marshall97a} is employed. A laplacian operator, $\nabla^2$, provides viscous |
122 |
|
|
dissipation. Thermal and haline diffusion is also represented by a laplacian operator. |
123 |
|
|
\\ |
124 |
|
|
|
125 |
|
|
Wind-stress momentum inputs are added to the momentum equations for both |
126 |
|
|
the zonal flow, $u$ and the merdional flow $v$, according to equations |
127 |
|
|
(\ref{EQ:global_forcing_fu}) and (\ref{EQ:global_forcing_fv}). |
128 |
|
|
Thermodynamic forcing inputs are added to the equations for |
129 |
|
|
potential temperature, $\theta$, and salinity, $S$, according to equations |
130 |
|
|
(\ref{EQ:global_forcing_ft}) and (\ref{EQ:global_forcing_fs}). |
131 |
|
|
This produces a set of equations solved in this configuration as follows: |
132 |
|
|
% {\fracktur} |
133 |
|
|
|
134 |
|
|
|
135 |
|
|
\begin{eqnarray} |
136 |
|
|
\label{EQ:model_equations} |
137 |
|
|
\frac{Du}{Dt} - fv + |
138 |
|
|
\frac{1}{\rho}\frac{\partial p^{'}}{\partial x} - |
139 |
|
|
A_{h}\nabla_{h}^2u - A_{z}\frac{\partial^{2}u}{\partial z^{2}} |
140 |
|
|
& = & |
141 |
|
|
{\cal F}_{u} |
142 |
|
|
\\ |
143 |
|
|
\frac{Dv}{Dt} + fu + |
144 |
|
|
\frac{1}{\rho}\frac{\partial p^{'}}{\partial y} - |
145 |
|
|
A_{h}\nabla_{h}^2v - A_{z}\frac{\partial^{2}v}{\partial z^{2}} |
146 |
|
|
& = & |
147 |
|
|
{\cal F}_{v} |
148 |
|
|
\\ |
149 |
|
|
\frac{\partial \eta}{\partial t} + \nabla_{h}\cdot \vec{u} |
150 |
|
|
&=& |
151 |
|
|
0 |
152 |
|
|
\\ |
153 |
|
|
\frac{D\theta}{Dt} - |
154 |
|
|
K_{h}\nabla_{h}^2\theta - \Gamma(K_{z})\frac{\partial^{2}\theta}{\partial z^{2}} |
155 |
|
|
& = & |
156 |
|
|
{\cal F}_{\theta} |
157 |
|
|
\\ |
158 |
|
|
\frac{D s}{Dt} - |
159 |
|
|
K_{h}\nabla_{h}^2 s - \Gamma(K_{z})\frac{\partial^{2} s}{\partial z^{2}} |
160 |
|
|
& = & |
161 |
|
|
{\cal F}_{s} |
162 |
|
|
\\ |
163 |
|
|
g\rho_{0} \eta + \int^{0}_{-z}\rho^{'} dz & = & p^{'} |
164 |
|
|
\\ |
165 |
|
|
\end{eqnarray} |
166 |
|
|
|
167 |
|
|
\noindent where $u$ and $v$ are the $x$ and $y$ components of the |
168 |
|
|
flow vector $\vec{u}$. The suffices ${s},{i}$ indicate surface and |
169 |
|
|
interior model levels respectively. As described in |
170 |
|
|
MITgcm Numerical Solution Procedure \cite{MITgcm_Numerical_Scheme}, the time |
171 |
|
|
evolution of potential temperature, $\theta$, equation is solved prognostically. |
172 |
|
|
The total pressure, $p$, is diagnosed by summing pressure due to surface |
173 |
|
|
elevation $\eta$ and the hydrostatic pressure. |
174 |
|
|
\\ |
175 |
|
|
|
176 |
|
|
\subsubsection{Numerical Stability Criteria} |
177 |
|
|
|
178 |
|
|
The laplacian dissipation coefficient, $A_{h}$, is set to $400 m s^{-1}$. |
179 |
|
|
This value is chosen to yield a Munk layer width \cite{Adcroft_thesis}, |
180 |
|
|
|
181 |
|
|
\begin{eqnarray} |
182 |
|
|
\label{EQ:munk_layer} |
183 |
|
|
M_{w} = \pi ( \frac { A_{h} }{ \beta } )^{\frac{1}{3}} |
184 |
|
|
\end{eqnarray} |
185 |
|
|
|
186 |
|
|
\noindent of $\approx 100$km. This is greater than the model |
187 |
|
|
resolution in mid-latitudes $\Delta x$, ensuring that the frictional |
188 |
|
|
boundary layer is well resolved. |
189 |
|
|
\\ |
190 |
|
|
|
191 |
|
|
\noindent The model is stepped forward with a |
192 |
|
|
time step $\delta t=1200$secs. With this time step the stability |
193 |
|
|
parameter to the horizontal laplacian friction \cite{Adcroft_thesis} |
194 |
|
|
|
195 |
|
|
\begin{eqnarray} |
196 |
|
|
\label{EQ:laplacian_stability} |
197 |
|
|
S_{l} = 4 \frac{A_{h} \delta t}{{\Delta x}^2} |
198 |
|
|
\end{eqnarray} |
199 |
|
|
|
200 |
|
|
\noindent evaluates to 0.012, which is well below the 0.3 upper limit |
201 |
|
|
for stability. |
202 |
|
|
\\ |
203 |
|
|
|
204 |
|
|
\noindent The vertical dissipation coefficient, $A_{z}$, is set to |
205 |
|
|
$1\times10^{-2} {\rm m}^2{\rm s}^{-1}$. The associated stability limit |
206 |
|
|
|
207 |
|
|
\begin{eqnarray} |
208 |
|
|
\label{EQ:laplacian_stability_z} |
209 |
|
|
S_{l} = 4 \frac{A_{z} \delta t}{{\Delta z}^2} |
210 |
|
|
\end{eqnarray} |
211 |
|
|
|
212 |
|
|
\noindent evaluates to $4.8 \times 10^{-5}$ which is again well below |
213 |
|
|
the upper limit. |
214 |
|
|
The values of $A_{h}$ and $A_{z}$ are also used for the horizontal ($K_{h}$) |
215 |
|
|
and vertical ($K_{z}$) diffusion coefficients for temperature respectively. |
216 |
|
|
\\ |
217 |
|
|
|
218 |
|
|
\noindent The numerical stability for inertial oscillations |
219 |
|
|
\cite{Adcroft_thesis} |
220 |
|
|
|
221 |
|
|
\begin{eqnarray} |
222 |
|
|
\label{EQ:inertial_stability} |
223 |
|
|
S_{i} = f^{2} {\delta t}^2 |
224 |
|
|
\end{eqnarray} |
225 |
|
|
|
226 |
|
|
\noindent evaluates to $0.0144$, which is well below the $0.5$ upper |
227 |
|
|
limit for stability. |
228 |
|
|
\\ |
229 |
|
|
|
230 |
|
|
\noindent The advective CFL \cite{Adcroft_thesis} for a extreme maximum |
231 |
|
|
horizontal flow |
232 |
|
|
speed of $ | \vec{u} | = 2 ms^{-1}$ |
233 |
|
|
|
234 |
|
|
\begin{eqnarray} |
235 |
|
|
\label{EQ:cfl_stability} |
236 |
|
|
S_{a} = \frac{| \vec{u} | \delta t}{ \Delta x} |
237 |
|
|
\end{eqnarray} |
238 |
|
|
|
239 |
|
|
\noindent evaluates to $5 \times 10^{-2}$. This is well below the stability |
240 |
|
|
limit of 0.5. |
241 |
|
|
\\ |
242 |
|
|
|
243 |
|
|
\noindent The stbility parameter for internal gravity waves |
244 |
|
|
\cite{Adcroft_thesis} |
245 |
|
|
|
246 |
|
|
\begin{eqnarray} |
247 |
|
|
\label{EQ:cfl_stability} |
248 |
|
|
S_{c} = \frac{c_{g} \delta t}{ \Delta x} |
249 |
|
|
\end{eqnarray} |
250 |
|
|
|
251 |
|
|
\noindent evaluates to $5 \times 10^{-2}$. This is well below the linear |
252 |
|
|
stability limit of 0.25. |
253 |
|
|
|
254 |
|
|
\subsection{Code Configuration} |
255 |
|
|
\label{SEC:code_config} |
256 |
|
|
|
257 |
|
|
The model configuration for this experiment resides under the |
258 |
|
|
directory {\it verification/exp1/}. The experiment files |
259 |
|
|
\begin{itemize} |
260 |
|
|
\item {\it input/data} |
261 |
|
|
\item {\it input/data.pkg} |
262 |
|
|
\item {\it input/eedata}, |
263 |
|
|
\item {\it input/windx.sin\_y}, |
264 |
|
|
\item {\it input/topog.box}, |
265 |
|
|
\item {\it code/CPP\_EEOPTIONS.h} |
266 |
|
|
\item {\it code/CPP\_OPTIONS.h}, |
267 |
|
|
\item {\it code/SIZE.h}. |
268 |
|
|
\end{itemize} |
269 |
|
|
contain the code customisations and parameter settings for this |
270 |
|
|
experiements. Below we describe the customisations |
271 |
|
|
to these files associated with this experiment. |
272 |
|
|
|
273 |
|
|
\subsubsection{File {\it input/data}} |
274 |
|
|
|
275 |
|
|
This file, reproduced completely below, specifies the main parameters |
276 |
|
|
for the experiment. The parameters that are significant for this configuration |
277 |
|
|
are |
278 |
|
|
|
279 |
|
|
\begin{itemize} |
280 |
|
|
|
281 |
|
|
\item Line 4, |
282 |
|
|
\begin{verbatim} tRef=20.,10.,8.,6., \end{verbatim} |
283 |
|
|
this line sets |
284 |
|
|
the initial and reference values of potential temperature at each model |
285 |
|
|
level in units of $^{\circ}$C. |
286 |
|
|
The entries are ordered from surface to depth. For each |
287 |
|
|
depth level the inital and reference profiles will be uniform in |
288 |
|
|
$x$ and $y$. |
289 |
|
|
|
290 |
|
|
\fbox{ |
291 |
|
|
\begin{minipage}{5.0in} |
292 |
|
|
{\it S/R INI\_THETA}({\it ini\_theta.F}) |
293 |
|
|
\end{minipage} |
294 |
|
|
} |
295 |
|
|
|
296 |
|
|
|
297 |
|
|
\item Line 6, |
298 |
|
|
\begin{verbatim} viscAz=1.E-2, \end{verbatim} |
299 |
|
|
this line sets the vertical laplacian dissipation coefficient to |
300 |
|
|
$1 \times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary conditions |
301 |
|
|
for this operator are specified later. This variable is copied into |
302 |
|
|
model general vertical coordinate variable {\bf viscAr}. |
303 |
|
|
|
304 |
|
|
\fbox{ |
305 |
|
|
\begin{minipage}{5.0in} |
306 |
|
|
{\it S/R CALC\_DIFFUSIVITY}({\it calc\_diffusivity.F}) |
307 |
|
|
\end{minipage} |
308 |
|
|
} |
309 |
|
|
|
310 |
|
|
\item Line 7, |
311 |
|
|
\begin{verbatim} |
312 |
|
|
viscAh=4.E2, |
313 |
|
|
\end{verbatim} |
314 |
|
|
this line sets the horizontal laplacian frictional dissipation coefficient to |
315 |
|
|
$1 \times 10^{-2} {\rm m^{2}s^{-1}}$. Boundary conditions |
316 |
|
|
for this operator are specified later. |
317 |
|
|
|
318 |
|
|
\item Lines 8, |
319 |
|
|
\begin{verbatim} |
320 |
|
|
no_slip_sides=.FALSE. |
321 |
|
|
\end{verbatim} |
322 |
|
|
this line selects a free-slip lateral boundary condition for |
323 |
|
|
the horizontal laplacian friction operator |
324 |
|
|
e.g. $\frac{\partial u}{\partial y}$=0 along boundaries in $y$ and |
325 |
|
|
$\frac{\partial v}{\partial x}$=0 along boundaries in $x$. |
326 |
|
|
|
327 |
|
|
\item Lines 9, |
328 |
|
|
\begin{verbatim} |
329 |
|
|
no_slip_bottom=.TRUE. |
330 |
|
|
\end{verbatim} |
331 |
|
|
this line selects a no-slip boundary condition for bottom |
332 |
|
|
boundary condition in the vertical laplacian friction operator |
333 |
|
|
e.g. $u=v=0$ at $z=-H$, where $H$ is the local depth of the domain. |
334 |
|
|
|
335 |
|
|
\item Line 10, |
336 |
|
|
\begin{verbatim} |
337 |
|
|
diffKhT=4.E2, |
338 |
|
|
\end{verbatim} |
339 |
|
|
this line sets the horizontal diffusion coefficient for temperature |
340 |
|
|
to $400\,{\rm m^{2}s^{-1}}$. The boundary condition on this |
341 |
|
|
operator is $\frac{\partial}{\partial x}=\frac{\partial}{\partial y}=0$ at |
342 |
|
|
all boundaries. |
343 |
|
|
|
344 |
|
|
\item Line 11, |
345 |
|
|
\begin{verbatim} |
346 |
|
|
diffKzT=1.E-2, |
347 |
|
|
\end{verbatim} |
348 |
|
|
this line sets the vertical diffusion coefficient for temperature |
349 |
|
|
to $10^{-2}\,{\rm m^{2}s^{-1}}$. The boundary condition on this |
350 |
|
|
operator is $\frac{\partial}{\partial z}$ = 0 on all boundaries. |
351 |
|
|
|
352 |
|
|
\item Line 13, |
353 |
|
|
\begin{verbatim} |
354 |
|
|
tAlpha=2.E-4, |
355 |
|
|
\end{verbatim} |
356 |
|
|
This line sets the thermal expansion coefficient for the fluid |
357 |
|
|
to $2 \times 10^{-4}\,{\rm degrees}^{-1}$ |
358 |
|
|
|
359 |
|
|
\fbox{ |
360 |
|
|
\begin{minipage}{5.0in} |
361 |
|
|
{\it S/R FIND\_RHO}({\it find\_rho.F}) |
362 |
|
|
\end{minipage} |
363 |
|
|
} |
364 |
|
|
|
365 |
|
|
\item Line 18, |
366 |
|
|
\begin{verbatim} |
367 |
|
|
eosType='LINEAR' |
368 |
|
|
\end{verbatim} |
369 |
|
|
This line selects the linear form of the equation of state. |
370 |
|
|
|
371 |
|
|
\fbox{ |
372 |
|
|
\begin{minipage}{5.0in} |
373 |
|
|
{\it S/R FIND\_RHO}({\it find\_rho.F}) |
374 |
|
|
\end{minipage} |
375 |
|
|
} |
376 |
|
|
|
377 |
|
|
|
378 |
|
|
|
379 |
|
|
\item Line 40, |
380 |
|
|
\begin{verbatim} |
381 |
|
|
usingSphericalPolarGrid=.TRUE., |
382 |
|
|
\end{verbatim} |
383 |
|
|
This line requests that the simulation be performed in a |
384 |
|
|
spherical polar coordinate system. It affects the interpretation of |
385 |
|
|
grid inoput parameters, for exampl {\bf delX} and {\bf delY} and |
386 |
|
|
causes the grid generation routines to initialise an internal grid based |
387 |
|
|
on spherical polar geometry. |
388 |
|
|
|
389 |
|
|
\fbox{ |
390 |
|
|
\begin{minipage}{5.0in} |
391 |
|
|
{\it S/R INI\_SPEHRICAL\_POLAR\_GRID}({\it ini\_spherical\_polar\_grid.F}) |
392 |
|
|
\end{minipage} |
393 |
|
|
} |
394 |
|
|
|
395 |
|
|
\item Line 41, |
396 |
|
|
\begin{verbatim} |
397 |
|
|
phiMin=0., |
398 |
|
|
\end{verbatim} |
399 |
|
|
This line sets the southern boundary of the modeled |
400 |
|
|
domain to $0^{\circ}$ latitude. This value affects both the |
401 |
|
|
generation of the locally orthogonal grid that the model |
402 |
|
|
uses internally and affects the initialisation of the coriolis force. |
403 |
|
|
Note - it is not required to set |
404 |
|
|
a longitude boundary, since the absolute longitude does |
405 |
|
|
not alter the kernel equation discretisation. |
406 |
|
|
|
407 |
|
|
\item Line 42, |
408 |
|
|
\begin{verbatim} |
409 |
|
|
delX=60*1., |
410 |
|
|
\end{verbatim} |
411 |
|
|
This line sets the horizontal grid spacing between each y-coordinate line |
412 |
|
|
in the discrete grid to $1^{\circ}$ in longitude. |
413 |
|
|
|
414 |
|
|
\item Line 43, |
415 |
|
|
\begin{verbatim} |
416 |
|
|
delY=60*1., |
417 |
|
|
\end{verbatim} |
418 |
|
|
This line sets the horizontal grid spacing between each y-coordinate line |
419 |
|
|
in the discrete grid to $1^{\circ}$ in latitude. |
420 |
|
|
|
421 |
|
|
\item Line 44, |
422 |
|
|
\begin{verbatim} |
423 |
|
|
delZ=500.,500.,500.,500., |
424 |
|
|
\end{verbatim} |
425 |
|
|
This line sets the vertical grid spacing between each z-coordinate line |
426 |
|
|
in the discrete grid to $500\,{\rm m}$, so that the total model depth |
427 |
|
|
is $2\,{\rm km}$. The variable {\bf delZ} is copied into the internal |
428 |
|
|
model coordinate variable {\bf delR} |
429 |
|
|
|
430 |
|
|
\fbox{ |
431 |
|
|
\begin{minipage}{5.0in} |
432 |
|
|
{\it S/R INI\_VERTICAL\_GRID}({\it ini\_vertical\_grid.F}) |
433 |
|
|
\end{minipage} |
434 |
|
|
} |
435 |
|
|
|
436 |
|
|
\item Line 47, |
437 |
|
|
\begin{verbatim} |
438 |
|
|
bathyFile='topog.box' |
439 |
|
|
\end{verbatim} |
440 |
|
|
This line specifies the name of the file from which the domain |
441 |
|
|
bathymetry is read. This file is a two-dimensional ($x,y$) map of |
442 |
|
|
depths. This file is assumed to contain 64-bit binary numbers |
443 |
|
|
giving the depth of the model at each grid cell, ordered with the x |
444 |
|
|
coordinate varying fastest. The points are ordered from low coordinate |
445 |
|
|
to high coordinate for both axes. The units and orientation of the |
446 |
|
|
depths in this file are the same as used in the MITgcm code. In this |
447 |
|
|
experiment, a depth of $0m$ indicates a solid wall and a depth |
448 |
|
|
of $-2000m$ indicates open ocean. The matlab program |
449 |
|
|
{\it input/gendata.m} shows an example of how to generate a |
450 |
|
|
bathymetry file. |
451 |
|
|
|
452 |
|
|
|
453 |
|
|
\item Line 50, |
454 |
|
|
\begin{verbatim} |
455 |
|
|
zonalWindFile='windx.sin_y' |
456 |
|
|
\end{verbatim} |
457 |
|
|
This line specifies the name of the file from which the x-direction |
458 |
|
|
surface wind stress is read. This file is also a two-dimensional |
459 |
|
|
($x,y$) map and is enumerated and formatted in the same manner as the |
460 |
|
|
bathymetry file. The matlab program {\it input/gendata.m} includes example |
461 |
|
|
code to generate a valid |
462 |
|
|
{\bf zonalWindFile} |
463 |
|
|
file. |
464 |
|
|
|
465 |
|
|
\end{itemize} |
466 |
|
|
|
467 |
|
|
\noindent other lines in the file {\it input/data} are standard values |
468 |
|
|
that are described in the MITgcm Getting Started and MITgcm Parameters |
469 |
|
|
notes. |
470 |
|
|
|
471 |
|
|
\begin{small} |
472 |
|
|
% \input{part3/case_studies/carbon_outgassing_sensitivity/input/data} |
473 |
|
|
\end{small} |
474 |
|
|
|
475 |
|
|
\subsubsection{File {\it input/data.pkg}} |
476 |
|
|
|
477 |
|
|
This file uses standard default values and does not contain |
478 |
|
|
customisations for this experiment. |
479 |
|
|
|
480 |
|
|
\subsubsection{File {\it input/eedata}} |
481 |
|
|
|
482 |
|
|
This file uses standard default values and does not contain |
483 |
|
|
customisations for this experiment. |
484 |
|
|
|
485 |
|
|
\subsubsection{File {\it input/windx.sin\_y}} |
486 |
|
|
|
487 |
|
|
The {\it input/windx.sin\_y} file specifies a two-dimensional ($x,y$) |
488 |
|
|
map of wind stress ,$\tau_{x}$, values. The units used are $Nm^{-2}$. |
489 |
|
|
Although $\tau_{x}$ is only a function of $y$n in this experiment |
490 |
|
|
this file must still define a complete two-dimensional map in order |
491 |
|
|
to be compatible with the standard code for loading forcing fields |
492 |
|
|
in MITgcm. The included matlab program {\it input/gendata.m} gives a complete |
493 |
|
|
code for creating the {\it input/windx.sin\_y} file. |
494 |
|
|
|
495 |
|
|
\subsubsection{File {\it input/topog.box}} |
496 |
|
|
|
497 |
|
|
|
498 |
|
|
The {\it input/topog.box} file specifies a two-dimensional ($x,y$) |
499 |
|
|
map of depth values. For this experiment values are either |
500 |
|
|
$0m$ or $-2000\,{\rm m}$, corresponding respectively to a wall or to deep |
501 |
|
|
ocean. The file contains a raw binary stream of data that is enumerated |
502 |
|
|
in the same way as standard MITgcm two-dimensional, horizontal arrays. |
503 |
|
|
The included matlab program {\it input/gendata.m} gives a complete |
504 |
|
|
code for creating the {\it input/topog.box} file. |
505 |
|
|
|
506 |
|
|
\subsubsection{File {\it code/SIZE.h}} |
507 |
|
|
|
508 |
|
|
Two lines are customized in this file for the current experiment |
509 |
|
|
|
510 |
|
|
\begin{itemize} |
511 |
|
|
|
512 |
|
|
\item Line 39, |
513 |
|
|
\begin{verbatim} sNx=60, \end{verbatim} this line sets |
514 |
|
|
the lateral domain extent in grid points for the |
515 |
|
|
axis aligned with the x-coordinate. |
516 |
|
|
|
517 |
|
|
\item Line 40, |
518 |
|
|
\begin{verbatim} sNy=60, \end{verbatim} this line sets |
519 |
|
|
the lateral domain extent in grid points for the |
520 |
|
|
axis aligned with the y-coordinate. |
521 |
|
|
|
522 |
|
|
\item Line 49, |
523 |
|
|
\begin{verbatim} Nr=4, \end{verbatim} this line sets |
524 |
|
|
the vertical domain extent in grid points. |
525 |
|
|
|
526 |
|
|
\end{itemize} |
527 |
|
|
|
528 |
|
|
\begin{small} |
529 |
|
|
% \include{code/SIZE.h} |
530 |
|
|
\end{small} |
531 |
|
|
|
532 |
|
|
\subsubsection{File {\it code/CPP\_OPTIONS.h}} |
533 |
|
|
|
534 |
|
|
This file uses standard default values and does not contain |
535 |
|
|
customisations for this experiment. |
536 |
|
|
|
537 |
|
|
|
538 |
|
|
\subsubsection{File {\it code/CPP\_EEOPTIONS.h}} |
539 |
|
|
|
540 |
|
|
This file uses standard default values and does not contain |
541 |
|
|
customisations for this experiment. |
542 |
|
|
|
543 |
|
|
\subsubsection{Other Files } |
544 |
|
|
|
545 |
|
|
Other files relevant to this experiment are |
546 |
|
|
\begin{itemize} |
547 |
|
|
\item {\it model/src/ini\_cori.F}. This file initializes the model |
548 |
|
|
coriolis variables {\bf fCorU}. |
549 |
|
|
\item {\it model/src/ini\_spherical\_polar\_grid.F} |
550 |
|
|
\item {\it model/src/ini\_parms.F}, |
551 |
|
|
\item {\it input/windx.sin\_y}, |
552 |
|
|
\end{itemize} |
553 |
|
|
contain the code customisations and parameter settings for this |
554 |
|
|
experiements. Below we describe the customisations |
555 |
|
|
to these files associated with this experiment. |