| 61 |
models - see fig \ref{fig:onemodel} |
models - see fig \ref{fig:onemodel} |
| 62 |
|
|
| 63 |
%% CNHbegin |
%% CNHbegin |
| 64 |
\input{part1/one_model_figure} |
\input{s_overview/text/one_model_figure} |
| 65 |
%% CNHend |
%% CNHend |
| 66 |
|
|
| 67 |
\item it has a non-hydrostatic capability and so can be used to study both |
\item it has a non-hydrostatic capability and so can be used to study both |
| 68 |
small-scale and large scale processes - see fig \ref{fig:all-scales} |
small-scale and large scale processes - see fig \ref{fig:all-scales} |
| 69 |
|
|
| 70 |
%% CNHbegin |
%% CNHbegin |
| 71 |
\input{part1/all_scales_figure} |
\input{s_overview/text/all_scales_figure} |
| 72 |
%% CNHend |
%% CNHend |
| 73 |
|
|
| 74 |
\item finite volume techniques are employed yielding an intuitive |
\item finite volume techniques are employed yielding an intuitive |
| 76 |
orthogonal curvilinear grids and shaved cells - see fig \ref{fig:finite-volumes} |
orthogonal curvilinear grids and shaved cells - see fig \ref{fig:finite-volumes} |
| 77 |
|
|
| 78 |
%% CNHbegin |
%% CNHbegin |
| 79 |
\input{part1/fvol_figure} |
\input{s_overview/text/fvol_figure} |
| 80 |
%% CNHend |
%% CNHend |
| 81 |
|
|
| 82 |
\item tangent linear and adjoint counterparts are automatically maintained |
\item tangent linear and adjoint counterparts are automatically maintained |
| 87 |
computational platforms. |
computational platforms. |
| 88 |
\end{itemize} |
\end{itemize} |
| 89 |
|
|
| 90 |
|
|
| 91 |
Key publications reporting on and charting the development of the model are |
Key publications reporting on and charting the development of the model are |
| 92 |
\cite{hill:95,marshall:97a,marshall:97b,adcroft:97,marshall:98,adcroft:99,hill:99,maro-eta:99}: |
\cite{hill:95,marshall:97a,marshall:97b,adcroft:97,mars-eta:98,adcroft:99,hill:99,maro-eta:99,adcroft:04a,adcroft:04b,marshall:04} |
| 93 |
|
(an overview on the model formulation can also be found in \cite{adcroft:04c}): |
| 94 |
|
|
| 95 |
\begin{verbatim} |
\begin{verbatim} |
| 96 |
Hill, C. and J. Marshall, (1995) |
Hill, C. and J. Marshall, (1995) |
| 144 |
|
|
| 145 |
\section{Illustrations of the model in action} |
\section{Illustrations of the model in action} |
| 146 |
|
|
| 147 |
The MITgcm has been designed and used to model a wide range of phenomena, |
MITgcm has been designed and used to model a wide range of phenomena, |
| 148 |
from convection on the scale of meters in the ocean to the global pattern of |
from convection on the scale of meters in the ocean to the global pattern of |
| 149 |
atmospheric winds - see figure \ref{fig:all-scales}. To give a flavor of the |
atmospheric winds - see figure \ref{fig:all-scales}. To give a flavor of the |
| 150 |
kinds of problems the model has been used to study, we briefly describe some |
kinds of problems the model has been used to study, we briefly describe some |
| 167 |
|
|
| 168 |
Figure \ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$ |
Figure \ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$ |
| 169 |
temperature field obtained using the atmospheric isomorph of MITgcm run at |
temperature field obtained using the atmospheric isomorph of MITgcm run at |
| 170 |
2.8$^{\circ }$ resolution on the cubed sphere. We see cold air over the pole |
$2.8^{\circ }$ resolution on the cubed sphere. We see cold air over the pole |
| 171 |
(blue) and warm air along an equatorial band (red). Fully developed |
(blue) and warm air along an equatorial band (red). Fully developed |
| 172 |
baroclinic eddies spawned in the northern hemisphere storm track are |
baroclinic eddies spawned in the northern hemisphere storm track are |
| 173 |
evident. There are no mountains or land-sea contrast in this calculation, |
evident. There are no mountains or land-sea contrast in this calculation, |
| 177 |
there are no mountains or land-sea contrast. |
there are no mountains or land-sea contrast. |
| 178 |
|
|
| 179 |
%% CNHbegin |
%% CNHbegin |
| 180 |
\input{part1/cubic_eddies_figure} |
\input{s_overview/text/cubic_eddies_figure} |
| 181 |
%% CNHend |
%% CNHend |
| 182 |
|
|
| 183 |
As described in Adcroft (2001), a `cubed sphere' is used to discretize the |
As described in Adcroft (2001), a `cubed sphere' is used to discretize the |
| 193 |
latitude-longitude grid. Both grids are supported within the model. |
latitude-longitude grid. Both grids are supported within the model. |
| 194 |
|
|
| 195 |
%% CNHbegin |
%% CNHbegin |
| 196 |
\input{part1/hs_zave_u_figure} |
\input{s_overview/text/hs_zave_u_figure} |
| 197 |
%% CNHend |
%% CNHend |
| 198 |
|
|
| 199 |
\subsection{Ocean gyres} |
\subsection{Ocean gyres} |
| 212 |
increased until the baroclinic instability process is resolved, numerical |
increased until the baroclinic instability process is resolved, numerical |
| 213 |
solutions of a different and much more realistic kind, can be obtained. |
solutions of a different and much more realistic kind, can be obtained. |
| 214 |
|
|
| 215 |
Figure \ref{fig:ocean-gyres} shows the surface temperature and velocity |
Figure \ref{fig:ocean-gyres} shows the surface temperature and |
| 216 |
field obtained from MITgcm run at $\frac{1}{6}^{\circ }$ horizontal |
velocity field obtained from MITgcm run at $\frac{1}{6}^{\circ }$ |
| 217 |
resolution on a $lat-lon$ |
horizontal resolution on a \textit{lat-lon} grid in which the pole has |
| 218 |
grid in which the pole has been rotated by 90$^{\circ }$ on to the equator |
been rotated by $90^{\circ }$ on to the equator (to avoid the |
| 219 |
(to avoid the converging of meridian in northern latitudes). 21 vertical |
converging of meridian in northern latitudes). 21 vertical levels are |
| 220 |
levels are used in the vertical with a `lopped cell' representation of |
used in the vertical with a `lopped cell' representation of |
| 221 |
topography. The development and propagation of anomalously warm and cold |
topography. The development and propagation of anomalously warm and |
| 222 |
eddies can be clearly seen in the Gulf Stream region. The transport of |
cold eddies can be clearly seen in the Gulf Stream region. The |
| 223 |
warm water northward by the mean flow of the Gulf Stream is also clearly |
transport of warm water northward by the mean flow of the Gulf Stream |
| 224 |
visible. |
is also clearly visible. |
| 225 |
|
|
| 226 |
%% CNHbegin |
%% CNHbegin |
| 227 |
\input{part1/atl6_figure} |
\input{s_overview/text/atl6_figure} |
| 228 |
%% CNHend |
%% CNHend |
| 229 |
|
|
| 230 |
|
|
| 233 |
<!-- CMIREDIR:global_ocean_circulation: --> |
<!-- CMIREDIR:global_ocean_circulation: --> |
| 234 |
\end{rawhtml} |
\end{rawhtml} |
| 235 |
|
|
| 236 |
Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean currents at |
Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean |
| 237 |
the surface of a 4$^{\circ }$ |
currents at the surface of a $4^{\circ }$ global ocean model run with |
| 238 |
global ocean model run with 15 vertical levels. Lopped cells are used to |
15 vertical levels. Lopped cells are used to represent topography on a |
| 239 |
represent topography on a regular $lat-lon$ grid extending from 70$^{\circ |
regular \textit{lat-lon} grid extending from $70^{\circ }N$ to |
| 240 |
}N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with |
$70^{\circ }S$. The model is driven using monthly-mean winds with |
| 241 |
mixed boundary conditions on temperature and salinity at the surface. The |
mixed boundary conditions on temperature and salinity at the surface. |
| 242 |
transfer properties of ocean eddies, convection and mixing is parameterized |
The transfer properties of ocean eddies, convection and mixing is |
| 243 |
in this model. |
parameterized in this model. |
| 244 |
|
|
| 245 |
Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning |
Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning |
| 246 |
circulation of the global ocean in Sverdrups. |
circulation of the global ocean in Sverdrups. |
| 247 |
|
|
| 248 |
%%CNHbegin |
%%CNHbegin |
| 249 |
\input{part1/global_circ_figure} |
\input{s_overview/text/global_circ_figure} |
| 250 |
%%CNHend |
%%CNHend |
| 251 |
|
|
| 252 |
\subsection{Convection and mixing over topography} |
\subsection{Convection and mixing over topography} |
| 269 |
instability of the along-slope current. |
instability of the along-slope current. |
| 270 |
|
|
| 271 |
%%CNHbegin |
%%CNHbegin |
| 272 |
\input{part1/convect_and_topo} |
\input{s_overview/text/convect_and_topo} |
| 273 |
%%CNHend |
%%CNHend |
| 274 |
|
|
| 275 |
\subsection{Boundary forced internal waves} |
\subsection{Boundary forced internal waves} |
| 291 |
nonhydrostatic dynamics. |
nonhydrostatic dynamics. |
| 292 |
|
|
| 293 |
%%CNHbegin |
%%CNHbegin |
| 294 |
\input{part1/boundary_forced_waves} |
\input{s_overview/text/boundary_forced_waves} |
| 295 |
%%CNHend |
%%CNHend |
| 296 |
|
|
| 297 |
\subsection{Parameter sensitivity using the adjoint of MITgcm} |
\subsection{Parameter sensitivity using the adjoint of MITgcm} |
| 303 |
`automatic adjoint compiler'. These can be used in parameter sensitivity and |
`automatic adjoint compiler'. These can be used in parameter sensitivity and |
| 304 |
data assimilation studies. |
data assimilation studies. |
| 305 |
|
|
| 306 |
As one example of application of the MITgcm adjoint, Figure \ref{fig:hf-sensitivity} |
As one example of application of the MITgcm adjoint, Figure |
| 307 |
maps the gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude |
\ref{fig:hf-sensitivity} maps the gradient $\frac{\partial J}{\partial |
| 308 |
of the overturning stream-function shown in figure \ref{fig:large-scale-circ} |
\mathcal{H}}$where $J$ is the magnitude of the overturning |
| 309 |
at 60$^{\circ }$N and $ |
stream-function shown in figure \ref{fig:large-scale-circ} at |
| 310 |
\mathcal{H}(\lambda,\varphi)$ is the mean, local air-sea heat flux over |
$60^{\circ }N$ and $ \mathcal{H}(\lambda,\varphi)$ is the mean, local |
| 311 |
a 100 year period. We see that $J$ is |
air-sea heat flux over a 100 year period. We see that $J$ is sensitive |
| 312 |
sensitive to heat fluxes over the Labrador Sea, one of the important sources |
to heat fluxes over the Labrador Sea, one of the important sources of |
| 313 |
of deep water for the thermohaline circulations. This calculation also |
deep water for the thermohaline circulations. This calculation also |
| 314 |
yields sensitivities to all other model parameters. |
yields sensitivities to all other model parameters. |
| 315 |
|
|
| 316 |
%%CNHbegin |
%%CNHbegin |
| 317 |
\input{part1/adj_hf_ocean_figure} |
\input{s_overview/text/adj_hf_ocean_figure} |
| 318 |
%%CNHend |
%%CNHend |
| 319 |
|
|
| 320 |
\subsection{Global state estimation of the ocean} |
\subsection{Global state estimation of the ocean} |
| 335 |
1992-1997. |
1992-1997. |
| 336 |
|
|
| 337 |
%% CNHbegin |
%% CNHbegin |
| 338 |
\input{part1/assim_figure} |
\input{s_overview/text/assim_figure} |
| 339 |
%% CNHend |
%% CNHend |
| 340 |
|
|
| 341 |
\subsection{Ocean biogeochemical cycles} |
\subsection{Ocean biogeochemical cycles} |
| 343 |
<!-- CMIREDIR:ocean_biogeo_cycles: --> |
<!-- CMIREDIR:ocean_biogeo_cycles: --> |
| 344 |
\end{rawhtml} |
\end{rawhtml} |
| 345 |
|
|
| 346 |
MITgcm is being used to study global biogeochemical cycles in the ocean. For |
MITgcm is being used to study global biogeochemical cycles in the |
| 347 |
example one can study the effects of interannual changes in meteorological |
ocean. For example one can study the effects of interannual changes in |
| 348 |
forcing and upper ocean circulation on the fluxes of carbon dioxide and |
meteorological forcing and upper ocean circulation on the fluxes of |
| 349 |
oxygen between the ocean and atmosphere. Figure \ref{fig:biogeo} shows |
carbon dioxide and oxygen between the ocean and atmosphere. Figure |
| 350 |
the annual air-sea flux of oxygen and its relation to density outcrops in |
\ref{fig:biogeo} shows the annual air-sea flux of oxygen and its |
| 351 |
the southern oceans from a single year of a global, interannually varying |
relation to density outcrops in the southern oceans from a single year |
| 352 |
simulation. The simulation is run at $1^{\circ}\times1^{\circ}$ resolution |
of a global, interannually varying simulation. The simulation is run |
| 353 |
telescoping to $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not shown). |
at $1^{\circ}\times1^{\circ}$ resolution telescoping to |
| 354 |
|
$\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not |
| 355 |
|
shown). |
| 356 |
|
|
| 357 |
%%CNHbegin |
%%CNHbegin |
| 358 |
\input{part1/biogeo_figure} |
\input{s_overview/text/biogeo_figure} |
| 359 |
%%CNHend |
%%CNHend |
| 360 |
|
|
| 361 |
\subsection{Simulations of laboratory experiments} |
\subsection{Simulations of laboratory experiments} |
| 373 |
stratification of the ACC. |
stratification of the ACC. |
| 374 |
|
|
| 375 |
%%CNHbegin |
%%CNHbegin |
| 376 |
\input{part1/lab_figure} |
\input{s_overview/text/lab_figure} |
| 377 |
%%CNHend |
%%CNHend |
| 378 |
|
|
| 379 |
% $Header$ |
% $Header$ |
| 396 |
\ref{fig:isomorphic-equations}). |
\ref{fig:isomorphic-equations}). |
| 397 |
|
|
| 398 |
%%CNHbegin |
%%CNHbegin |
| 399 |
\input{part1/zandpcoord_figure.tex} |
\input{s_overview/text/zandpcoord_figure.tex} |
| 400 |
%%CNHend |
%%CNHend |
| 401 |
|
|
| 402 |
The state of the fluid at any time is characterized by the distribution of |
The state of the fluid at any time is characterized by the distribution of |
| 410 |
see figure \ref{fig:zandp-vert-coord}. |
see figure \ref{fig:zandp-vert-coord}. |
| 411 |
|
|
| 412 |
%%CNHbegin |
%%CNHbegin |
| 413 |
\input{part1/vertcoord_figure.tex} |
\input{s_overview/text/vertcoord_figure.tex} |
| 414 |
%%CNHend |
%%CNHend |
| 415 |
|
|
| 416 |
\begin{equation} |
\begin{equation} |
| 661 |
|
|
| 662 |
\subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and |
\subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and |
| 663 |
Non-hydrostatic forms} |
Non-hydrostatic forms} |
| 664 |
|
\label{sec:all_hydrostatic_forms} |
| 665 |
\begin{rawhtml} |
\begin{rawhtml} |
| 666 |
<!-- CMIREDIR:non_hydrostatic: --> |
<!-- CMIREDIR:non_hydrostatic: --> |
| 667 |
\end{rawhtml} |
\end{rawhtml} |
| 770 |
OPERATORS. |
OPERATORS. |
| 771 |
|
|
| 772 |
%%CNHbegin |
%%CNHbegin |
| 773 |
\input{part1/sphere_coord_figure.tex} |
\input{s_overview/text/sphere_coord_figure.tex} |
| 774 |
%%CNHend |
%%CNHend |
| 775 |
|
|
| 776 |
\subsubsection{Shallow atmosphere approximation} |
\subsubsection{Shallow atmosphere approximation} |
| 777 |
|
|
| 778 |
Most models are based on the `hydrostatic primitive equations' (HPE's) in |
Most models are based on the `hydrostatic primitive equations' (HPE's) |
| 779 |
which the vertical momentum equation is reduced to a statement of |
in which the vertical momentum equation is reduced to a statement of |
| 780 |
hydrostatic balance and the `traditional approximation' is made in which the |
hydrostatic balance and the `traditional approximation' is made in |
| 781 |
Coriolis force is treated approximately and the shallow atmosphere |
which the Coriolis force is treated approximately and the shallow |
| 782 |
approximation is made.\ The MITgcm need not make the `traditional |
atmosphere approximation is made. MITgcm need not make the |
| 783 |
approximation'. To be able to support consistent non-hydrostatic forms the |
`traditional approximation'. To be able to support consistent |
| 784 |
shallow atmosphere approximation can be relaxed - when dividing through by $ |
non-hydrostatic forms the shallow atmosphere approximation can be |
| 785 |
r $ in, for example, (\ref{eq:gu-speherical}), we do not replace $r$ by $a$, |
relaxed - when dividing through by $ r $ in, for example, |
| 786 |
the radius of the earth. |
(\ref{eq:gu-speherical}), we do not replace $r$ by $a$, the radius of |
| 787 |
|
the earth. |
| 788 |
|
|
| 789 |
\subsubsection{Hydrostatic and quasi-hydrostatic forms} |
\subsubsection{Hydrostatic and quasi-hydrostatic forms} |
| 790 |
\label{sec:hydrostatic_and_quasi-hydrostatic_forms} |
\label{sec:hydrostatic_and_quasi-hydrostatic_forms} |
| 821 |
|
|
| 822 |
\subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms} |
\subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms} |
| 823 |
|
|
| 824 |
The MIT model presently supports a full non-hydrostatic ocean isomorph, but |
MITgcm presently supports a full non-hydrostatic ocean isomorph, but |
| 825 |
only a quasi-non-hydrostatic atmospheric isomorph. |
only a quasi-non-hydrostatic atmospheric isomorph. |
| 826 |
|
|
| 827 |
\paragraph{Non-hydrostatic Ocean} |
\paragraph{Non-hydrostatic Ocean} |
| 891 |
stepping forward the vertical momentum equation. |
stepping forward the vertical momentum equation. |
| 892 |
|
|
| 893 |
%%CNHbegin |
%%CNHbegin |
| 894 |
\input{part1/solution_strategy_figure.tex} |
\input{s_overview/text/solution_strategy_figure.tex} |
| 895 |
%%CNHend |
%%CNHend |
| 896 |
|
|
| 897 |
There is no penalty in implementing \textbf{QH} over \textbf{HPE} except, of |
There is no penalty in implementing \textbf{QH} over \textbf{HPE} except, of |
| 1080 |
|
|
| 1081 |
The mixing terms for the temperature and salinity equations have a similar |
The mixing terms for the temperature and salinity equations have a similar |
| 1082 |
form to that of momentum except that the diffusion tensor can be |
form to that of momentum except that the diffusion tensor can be |
| 1083 |
non-diagonal and have varying coefficients. $\qquad $ |
non-diagonal and have varying coefficients. |
| 1084 |
\begin{equation} |
\begin{equation} |
| 1085 |
D_{T,S}=\nabla .[\underline{\underline{K}}\nabla (T,S)]+K_{4}\nabla |
D_{T,S}=\nabla .[\underline{\underline{K}}\nabla (T,S)]+K_{4}\nabla |
| 1086 |
_{h}^{4}(T,S) \label{eq:diffusion} |
_{h}^{4}(T,S) \label{eq:diffusion} |
| 1492 |
\end{equation*} |
\end{equation*} |
| 1493 |
|
|
| 1494 |
\begin{equation*} |
\begin{equation*} |
| 1495 |
v=r\frac{D\varphi }{Dt}\qquad |
v=r\frac{D\varphi }{Dt} |
| 1496 |
\end{equation*} |
\end{equation*} |
|
$\qquad \qquad \qquad \qquad $ |
|
| 1497 |
|
|
| 1498 |
\begin{equation*} |
\begin{equation*} |
| 1499 |
\dot{r}=\frac{Dr}{Dt} |
\dot{r}=\frac{Dr}{Dt} |
| 1503 |
distance of the particle from the center of the earth, $\Omega $ is the |
distance of the particle from the center of the earth, $\Omega $ is the |
| 1504 |
angular speed of rotation of the Earth and $D/Dt$ is the total derivative. |
angular speed of rotation of the Earth and $D/Dt$ is the total derivative. |
| 1505 |
|
|
| 1506 |
The `grad' ($\nabla $) and `div' ($\nabla $.) operators are defined by, in |
The `grad' ($\nabla $) and `div' ($\nabla\cdot$) operators are defined by, in |
| 1507 |
spherical coordinates: |
spherical coordinates: |
| 1508 |
|
|
| 1509 |
\begin{equation*} |
\begin{equation*} |
| 1513 |
\end{equation*} |
\end{equation*} |
| 1514 |
|
|
| 1515 |
\begin{equation*} |
\begin{equation*} |
| 1516 |
\nabla .v\equiv \frac{1}{r\cos \varphi }\left\{ \frac{\partial u}{\partial |
\nabla\cdot v\equiv \frac{1}{r\cos \varphi }\left\{ \frac{\partial u}{\partial |
| 1517 |
\lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\} |
\lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\} |
| 1518 |
+\frac{1}{r^{2}}\frac{\partial \left( r^{2}\dot{r}\right) }{\partial r} |
+\frac{1}{r^{2}}\frac{\partial \left( r^{2}\dot{r}\right) }{\partial r} |
| 1519 |
\end{equation*} |
\end{equation*} |