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revision 1.21 by edhill, Sat Oct 16 03:40:12 2004 UTC revision 1.26 by edhill, Wed Jun 28 15:22:13 2006 UTC
# Line 88  computational platforms. Line 88  computational platforms.
88  \end{itemize}  \end{itemize}
89    
90  Key publications reporting on and charting the development of the model are  Key publications reporting on and charting the development of the model are
91  \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,marshall:98,adcroft:99,hill:99,maro-eta:99,adcroft:04a,adcroft:04b,marshall:04}:
92    
93  \begin{verbatim}  \begin{verbatim}
94  Hill, C. and J. Marshall, (1995)  Hill, C. and J. Marshall, (1995)
# Line 142  give a feel for the wide range of proble Line 142  give a feel for the wide range of proble
142    
143  \section{Illustrations of the model in action}  \section{Illustrations of the model in action}
144    
145  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,
146  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
147  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
148  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
# Line 165  both atmospheric and oceanographic flows Line 165  both atmospheric and oceanographic flows
165    
166  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$mb$
167  temperature field obtained using the atmospheric isomorph of MITgcm run at  temperature field obtained using the atmospheric isomorph of MITgcm run at
168  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
169  (blue) and warm air along an equatorial band (red). Fully developed  (blue) and warm air along an equatorial band (red). Fully developed
170  baroclinic eddies spawned in the northern hemisphere storm track are  baroclinic eddies spawned in the northern hemisphere storm track are
171  evident. There are no mountains or land-sea contrast in this calculation,  evident. There are no mountains or land-sea contrast in this calculation,
# Line 210  diffusive patterns of ocean currents. Bu Line 210  diffusive patterns of ocean currents. Bu
210  increased until the baroclinic instability process is resolved, numerical  increased until the baroclinic instability process is resolved, numerical
211  solutions of a different and much more realistic kind, can be obtained.  solutions of a different and much more realistic kind, can be obtained.
212    
213  Figure \ref{fig:ocean-gyres} shows the surface temperature and velocity  Figure \ref{fig:ocean-gyres} shows the surface temperature and
214  field obtained from MITgcm run at $\frac{1}{6}^{\circ }$ horizontal  velocity field obtained from MITgcm run at $\frac{1}{6}^{\circ }$
215  resolution on a $lat-lon$  horizontal resolution on a \textit{lat-lon} grid in which the pole has
216  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
217  (to avoid the converging of meridian in northern latitudes). 21 vertical  converging of meridian in northern latitudes). 21 vertical levels are
218  levels are used in the vertical with a `lopped cell' representation of  used in the vertical with a `lopped cell' representation of
219  topography. The development and propagation of anomalously warm and cold  topography. The development and propagation of anomalously warm and
220  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
221  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
222  visible.  is also clearly visible.
223    
224  %% CNHbegin  %% CNHbegin
225  \input{part1/atl6_figure}  \input{part1/atl6_figure}
# Line 231  visible. Line 231  visible.
231  <!-- CMIREDIR:global_ocean_circulation: -->  <!-- CMIREDIR:global_ocean_circulation: -->
232  \end{rawhtml}  \end{rawhtml}
233    
234  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
235  the surface of a 4$^{\circ }$  currents at the surface of a $4^{\circ }$ global ocean model run with
236  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
237  represent topography on a regular $lat-lon$ grid extending from 70$^{\circ  regular \textit{lat-lon} grid extending from $70^{\circ }N$ to
238  }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
239  mixed boundary conditions on temperature and salinity at the surface. The  mixed boundary conditions on temperature and salinity at the surface.
240  transfer properties of ocean eddies, convection and mixing is parameterized  The transfer properties of ocean eddies, convection and mixing is
241  in this model.  parameterized in this model.
242    
243  Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning  Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning
244  circulation of the global ocean in Sverdrups.  circulation of the global ocean in Sverdrups.
# Line 301  Forward and tangent linear counterparts Line 301  Forward and tangent linear counterparts
301  `automatic adjoint compiler'. These can be used in parameter sensitivity and  `automatic adjoint compiler'. These can be used in parameter sensitivity and
302  data assimilation studies.  data assimilation studies.
303    
304  As one example of application of the MITgcm adjoint, Figure \ref{fig:hf-sensitivity}  As one example of application of the MITgcm adjoint, Figure
305  maps the gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude  \ref{fig:hf-sensitivity} maps the gradient $\frac{\partial J}{\partial
306  of the overturning stream-function shown in figure \ref{fig:large-scale-circ}    \mathcal{H}}$where $J$ is the magnitude of the overturning
307  at 60$^{\circ }$N and $  stream-function shown in figure \ref{fig:large-scale-circ} at
308  \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
309  a 100 year period. We see that $J$ is  air-sea heat flux over a 100 year period. We see that $J$ is sensitive
310  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
311  of deep water for the thermohaline circulations. This calculation also  deep water for the thermohaline circulations. This calculation also
312  yields sensitivities to all other model parameters.  yields sensitivities to all other model parameters.
313    
314  %%CNHbegin  %%CNHbegin
# Line 341  consistency with altimetric and in-situ Line 341  consistency with altimetric and in-situ
341  <!-- CMIREDIR:ocean_biogeo_cycles: -->  <!-- CMIREDIR:ocean_biogeo_cycles: -->
342  \end{rawhtml}  \end{rawhtml}
343    
344  MITgcm is being used to study global biogeochemical cycles in the ocean. For  MITgcm is being used to study global biogeochemical cycles in the
345  example one can study the effects of interannual changes in meteorological  ocean. For example one can study the effects of interannual changes in
346  forcing and upper ocean circulation on the fluxes of carbon dioxide and  meteorological forcing and upper ocean circulation on the fluxes of
347  oxygen between the ocean and atmosphere. Figure \ref{fig:biogeo} shows  carbon dioxide and oxygen between the ocean and atmosphere. Figure
348  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
349  the southern oceans from a single year of a global, interannually varying  relation to density outcrops in the southern oceans from a single year
350  simulation. The simulation is run at $1^{\circ}\times1^{\circ}$ resolution  of a global, interannually varying simulation. The simulation is run
351  telescoping to $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not shown).  at $1^{\circ}\times1^{\circ}$ resolution telescoping to
352    $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not
353    shown).
354    
355  %%CNHbegin  %%CNHbegin
356  \input{part1/biogeo_figure}  \input{part1/biogeo_figure}
# Line 770  OPERATORS. Line 772  OPERATORS.
772    
773  \subsubsection{Shallow atmosphere approximation}  \subsubsection{Shallow atmosphere approximation}
774    
775  Most models are based on the `hydrostatic primitive equations' (HPE's) in  Most models are based on the `hydrostatic primitive equations' (HPE's)
776  which the vertical momentum equation is reduced to a statement of  in which the vertical momentum equation is reduced to a statement of
777  hydrostatic balance and the `traditional approximation' is made in which the  hydrostatic balance and the `traditional approximation' is made in
778  Coriolis force is treated approximately and the shallow atmosphere  which the Coriolis force is treated approximately and the shallow
779  approximation is made.\ The MITgcm need not make the `traditional  atmosphere approximation is made.  MITgcm need not make the
780  approximation'. To be able to support consistent non-hydrostatic forms the  `traditional approximation'. To be able to support consistent
781  shallow atmosphere approximation can be relaxed - when dividing through by $  non-hydrostatic forms the shallow atmosphere approximation can be
782  r $ in, for example, (\ref{eq:gu-speherical}), we do not replace $r$ by $a$,  relaxed - when dividing through by $ r $ in, for example,
783  the radius of the earth.  (\ref{eq:gu-speherical}), we do not replace $r$ by $a$, the radius of
784    the earth.
785    
786  \subsubsection{Hydrostatic and quasi-hydrostatic forms}  \subsubsection{Hydrostatic and quasi-hydrostatic forms}
787  \label{sec:hydrostatic_and_quasi-hydrostatic_forms}  \label{sec:hydrostatic_and_quasi-hydrostatic_forms}
# Line 815  et.al., 1997a. As in \textbf{HPE }only a Line 818  et.al., 1997a. As in \textbf{HPE }only a
818    
819  \subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms}  \subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms}
820    
821  The MIT model presently supports a full non-hydrostatic ocean isomorph, but  MITgcm presently supports a full non-hydrostatic ocean isomorph, but
822  only a quasi-non-hydrostatic atmospheric isomorph.  only a quasi-non-hydrostatic atmospheric isomorph.
823    
824  \paragraph{Non-hydrostatic Ocean}  \paragraph{Non-hydrostatic Ocean}
# Line 1074  friction. These coefficients are the sam Line 1077  friction. These coefficients are the sam
1077    
1078  The mixing terms for the temperature and salinity equations have a similar  The mixing terms for the temperature and salinity equations have a similar
1079  form to that of momentum except that the diffusion tensor can be  form to that of momentum except that the diffusion tensor can be
1080  non-diagonal and have varying coefficients. $\qquad $  non-diagonal and have varying coefficients.
1081  \begin{equation}  \begin{equation}
1082  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
1083  _{h}^{4}(T,S)  \label{eq:diffusion}  _{h}^{4}(T,S)  \label{eq:diffusion}
# Line 1213  In $p$-coordinates, the upper boundary a Line 1216  In $p$-coordinates, the upper boundary a
1216  surface ($\phi $ is imposed and $\omega \neq 0$).  surface ($\phi $ is imposed and $\omega \neq 0$).
1217    
1218  \subsubsection{Splitting the geo-potential}  \subsubsection{Splitting the geo-potential}
1219    \label{sec:hpe-p-geo-potential-split}
1220    
1221  For the purposes of initialization and reducing round-off errors, the model  For the purposes of initialization and reducing round-off errors, the model
1222  deals with perturbations from reference (or ``standard'') profiles. For  deals with perturbations from reference (or ``standard'') profiles. For
# Line 1485  u=r\cos \varphi \frac{D\lambda }{Dt} Line 1489  u=r\cos \varphi \frac{D\lambda }{Dt}
1489  \end{equation*}  \end{equation*}
1490    
1491  \begin{equation*}  \begin{equation*}
1492  v=r\frac{D\varphi }{Dt}\qquad  v=r\frac{D\varphi }{Dt}
1493  \end{equation*}  \end{equation*}
 $\qquad \qquad \qquad \qquad $  
1494    
1495  \begin{equation*}  \begin{equation*}
1496  \dot{r}=\frac{Dr}{Dt}  \dot{r}=\frac{Dr}{Dt}
# Line 1497  Here $\varphi $ is the latitude, $\lambd Line 1500  Here $\varphi $ is the latitude, $\lambd
1500  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
1501  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.
1502    
1503  The `grad' ($\nabla $) and `div' ($\nabla $.) operators are defined by, in  The `grad' ($\nabla $) and `div' ($\nabla\cdot$) operators are defined by, in
1504  spherical coordinates:  spherical coordinates:
1505    
1506  \begin{equation*}  \begin{equation*}
# Line 1507  spherical coordinates: Line 1510  spherical coordinates:
1510  \end{equation*}  \end{equation*}
1511    
1512  \begin{equation*}  \begin{equation*}
1513  \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
1514  \lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\}  \lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\}
1515  +\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}
1516  \end{equation*}  \end{equation*}

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