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revision 1.16 by cnh, Thu Feb 28 19:32:19 2002 UTC revision 1.29 by jmc, Mon Aug 30 23:09:21 2010 UTC
# Line 48  both process and general circulation stu Line 48  both process and general circulation stu
48  also presented.  also presented.
49    
50  \section{Introduction}  \section{Introduction}
51    \begin{rawhtml}
52    <!-- CMIREDIR:innovations: -->
53    \end{rawhtml}
54    
55    
56  MITgcm has a number of novel aspects:  MITgcm has a number of novel aspects:
57    
# Line 57  hydrodynamical kernel is used to drive f Line 61  hydrodynamical kernel is used to drive f
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
# Line 72  discretization and support for the treat Line 76  discretization and support for the treat
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
# Line 83  studies. Line 87  studies.
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)
# Line 138  give a feel for the wide range of proble Line 144  give a feel for the wide range of proble
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
# Line 150  running Linux, together with a FORTRAN\ Line 156  running Linux, together with a FORTRAN\
156  described in detail in the documentation.  described in detail in the documentation.
157    
158  \subsection{Global atmosphere: `Held-Suarez' benchmark}  \subsection{Global atmosphere: `Held-Suarez' benchmark}
159    \begin{rawhtml}
160    <!-- CMIREDIR:atmospheric_example: -->
161    \end{rawhtml}
162    
163    
164    
165  A novel feature of MITgcm is its ability to simulate, using one basic algorithm,  A novel feature of MITgcm is its ability to simulate, using one basic algorithm,
166  both atmospheric and oceanographic flows at both small and large scales.  both atmospheric and oceanographic flows at both small and large scales.
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,
# Line 166  in Held and Suarez; 1994 designed to tes Line 177  in Held and Suarez; 1994 designed to tes
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
# Line 182  cube-sphere grid and the flow calculated Line 193  cube-sphere grid and the flow calculated
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}
200    \begin{rawhtml}
201    <!-- CMIREDIR:oceanic_example: -->
202    \end{rawhtml}
203    \begin{rawhtml}
204    <!-- CMIREDIR:ocean_gyres: -->
205    \end{rawhtml}
206    
207  Baroclinic instability is a ubiquitous process in the ocean, as well as the  Baroclinic instability is a ubiquitous process in the ocean, as well as the
208  atmosphere. Ocean eddies play an important role in modifying the  atmosphere. Ocean eddies play an important role in modifying the
# Line 195  diffusive patterns of ocean currents. Bu Line 212  diffusive patterns of ocean currents. Bu
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    
231  \subsection{Global ocean circulation}  \subsection{Global ocean circulation}
232    \begin{rawhtml}
233  Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean currents at  <!-- CMIREDIR:global_ocean_circulation: -->
234  the surface of a 4$^{\circ }$  \end{rawhtml}
235  global ocean model run with 15 vertical levels. Lopped cells are used to  
236  represent topography on a regular $lat-lon$ grid extending from 70$^{\circ  Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean
237  }N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with  currents at the surface of a $4^{\circ }$ global ocean model run with
238  mixed boundary conditions on temperature and salinity at the surface. The  15 vertical levels. Lopped cells are used to represent topography on a
239  transfer properties of ocean eddies, convection and mixing is parameterized  regular \textit{lat-lon} grid extending from $70^{\circ }N$ to
240  in this model.  $70^{\circ }S$. The model is driven using monthly-mean winds with
241    mixed boundary conditions on temperature and salinity at the surface.
242    The transfer properties of ocean eddies, convection and mixing is
243    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}
253    \begin{rawhtml}
254    <!-- CMIREDIR:mixing_over_topography: -->
255    \end{rawhtml}
256    
257    
258  Dense plumes generated by localized cooling on the continental shelf of the  Dense plumes generated by localized cooling on the continental shelf of the
259  ocean may be influenced by rotation when the deformation radius is smaller  ocean may be influenced by rotation when the deformation radius is smaller
# Line 245  strong, and replaced by lateral entrainm Line 269  strong, and replaced by lateral entrainm
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}
276    \begin{rawhtml}
277    <!-- CMIREDIR:boundary_forced_internal_waves: -->
278    \end{rawhtml}
279    
280  The unique ability of MITgcm to treat non-hydrostatic dynamics in the  The unique ability of MITgcm to treat non-hydrostatic dynamics in the
281  presence of complex geometry makes it an ideal tool to study internal wave  presence of complex geometry makes it an ideal tool to study internal wave
# Line 264  using MITgcm's finite volume spatial dis Line 291  using MITgcm's finite volume spatial dis
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}
298    \begin{rawhtml}
299    <!-- CMIREDIR:parameter_sensitivity: -->
300    \end{rawhtml}
301    
302  Forward and tangent linear counterparts of MITgcm are supported using an  Forward and tangent linear counterparts of MITgcm are supported using an
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}
321    \begin{rawhtml}
322    <!-- CMIREDIR:global_state_estimation: -->
323    \end{rawhtml}
324    
325    
326  An important application of MITgcm is in state estimation of the global  An important application of MITgcm is in state estimation of the global
327  ocean circulation. An appropriately defined `cost function', which measures  ocean circulation. An appropriately defined `cost function', which measures
# Line 301  consistency with altimetric and in-situ Line 335  consistency with altimetric and in-situ
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}
342    \begin{rawhtml}
343  MITgcm is being used to study global biogeochemical cycles in the ocean. For  <!-- CMIREDIR:ocean_biogeo_cycles: -->
344  example one can study the effects of interannual changes in meteorological  \end{rawhtml}
345  forcing and upper ocean circulation on the fluxes of carbon dioxide and  
346  oxygen between the ocean and atmosphere. Figure \ref{fig:biogeo} shows  MITgcm is being used to study global biogeochemical cycles in the
347  the annual air-sea flux of oxygen and its relation to density outcrops in  ocean. For example one can study the effects of interannual changes in
348  the southern oceans from a single year of a global, interannually varying  meteorological forcing and upper ocean circulation on the fluxes of
349  simulation. The simulation is run at $1^{\circ}\times1^{\circ}$ resolution  carbon dioxide and oxygen between the ocean and atmosphere. Figure
350  telescoping to $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not shown).  \ref{fig:biogeo} shows the annual air-sea flux of oxygen and its
351    relation to density outcrops in the southern oceans from a single year
352    of a global, interannually varying simulation. The simulation is run
353    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}
362    \begin{rawhtml}
363    <!-- CMIREDIR:classroom_exp: -->
364    \end{rawhtml}
365    
366  Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a  Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a
367  laboratory experiment inquiring in to the dynamics of the Antarctic Circumpolar Current (ACC). An  laboratory experiment inquiring into the dynamics of the Antarctic Circumpolar Current (ACC). An
368  initially homogeneous tank of water ($1m$ in diameter) is driven from its  initially homogeneous tank of water ($1m$ in diameter) is driven from its
369  free surface by a rotating heated disk. The combined action of mechanical  free surface by a rotating heated disk. The combined action of mechanical
370  and thermal forcing creates a lens of fluid which becomes baroclinically  and thermal forcing creates a lens of fluid which becomes baroclinically
# Line 331  arrested by its instability in a process Line 373  arrested by its instability in a process
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  % $Header$  % $Header$
380  % $Name$  % $Name$
381    
382  \section{Continuous equations in `r' coordinates}  \section{Continuous equations in `r' coordinates}
383    \begin{rawhtml}
384    <!-- CMIREDIR:z-p_isomorphism: -->
385    \end{rawhtml}
386    
387  To render atmosphere and ocean models from one dynamical core we exploit  To render atmosphere and ocean models from one dynamical core we exploit
388  `isomorphisms' between equation sets that govern the evolution of the  `isomorphisms' between equation sets that govern the evolution of the
# Line 346  One system of hydrodynamical equations i Line 391  One system of hydrodynamical equations i
391  and encoded. The model variables have different interpretations depending on  and encoded. The model variables have different interpretations depending on
392  whether the atmosphere or ocean is being studied. Thus, for example, the  whether the atmosphere or ocean is being studied. Thus, for example, the
393  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are
394  modeling the atmosphere (left hand side of figure \ref{fig:isomorphic-equations})  modeling the atmosphere (right hand side of figure \ref{fig:isomorphic-equations})
395  and height, $z$, if we are modeling the ocean (right hand side of figure  and height, $z$, if we are modeling the ocean (left hand side of figure
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
# Line 365  kinematic boundary conditions can be app Line 410  kinematic boundary conditions can be app
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}
417  \frac{D\vec{\mathbf{v}_{h}}}{Dt}+\left( 2\vec{\Omega}\times \vec{\mathbf{v}}  \frac{D\vec{\mathbf{v}_{h}}}{Dt}+\left( 2\vec{\Omega}\times \vec{\mathbf{v}}
418  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}
419  \text{ horizontal mtm} \label{eq:horizontal_mtm}  \text{ horizontal mtm} \label{eq:horizontal_mtm}
420  \end{equation*}  \end{equation}
421    
422  \begin{equation}  \begin{equation}
423  \frac{D\dot{r}}{Dt}+\widehat{k}\cdot \left( 2\vec{\Omega}\times \vec{\mathbf{  \frac{D\dot{r}}{Dt}+\widehat{k}\cdot \left( 2\vec{\Omega}\times \vec{\mathbf{
# Line 471  in later chapters. Line 516  in later chapters.
516  at fixed and moving $r$ surfaces we set (see figure \ref{fig:zandp-vert-coord}):  at fixed and moving $r$ surfaces we set (see figure \ref{fig:zandp-vert-coord}):
517    
518  \begin{equation}  \begin{equation}
519  \dot{r}=0atr=R_{fixed}(x,y)\text{ (ocean bottom, top of the atmosphere)}  \dot{r}=0 \text{\ at\ } r=R_{fixed}(x,y)\text{ (ocean bottom, top of the atmosphere)}
520  \label{eq:fixedbc}  \label{eq:fixedbc}
521  \end{equation}  \end{equation}
522    
523  \begin{equation}  \begin{equation}
524  \dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \  \dot{r}=\frac{Dr}{Dt} \text{\ at\ } r=R_{moving}\text{ \
525  (ocean surface,bottom of the atmosphere)}  \label{eq:movingbc}  (ocean surface,bottom of the atmosphere)}  \label{eq:movingbc}
526  \end{equation}  \end{equation}
527    
# Line 570  The boundary conditions at top and botto Line 615  The boundary conditions at top and botto
615  atmosphere)}  \label{eq:moving-bc-atmos}  atmosphere)}  \label{eq:moving-bc-atmos}
616  \end{eqnarray}  \end{eqnarray}
617    
618  Then the (hydrostatic form of) equations (\ref{eq:horizontal_mtm}-\ref{eq:humidity_salt})  Then the (hydrostatic form of) equations
619  yields a consistent set of atmospheric equations which, for convenience, are written out in $p$  (\ref{eq:horizontal_mtm}-\ref{eq:humidity_salt}) yields a consistent
620  coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}).  set of atmospheric equations which, for convenience, are written out
621    in $p$ coordinates in Appendix Atmosphere - see
622    eqs(\ref{eq:atmos-prime}).
623    
624  \subsection{Ocean}  \subsection{Ocean}
625    
# Line 614  which, for convenience, are written out Line 661  which, for convenience, are written out
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}
666    <!-- CMIREDIR:non_hydrostatic: -->
667    \end{rawhtml}
668    
669    
670  Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms:  Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms:
671    
# Line 621  Let us separate $\phi $ in to surface, h Line 673  Let us separate $\phi $ in to surface, h
673  \phi (x,y,r)=\phi _{s}(x,y)+\phi _{hyd}(x,y,r)+\phi _{nh}(x,y,r)  \phi (x,y,r)=\phi _{s}(x,y)+\phi _{hyd}(x,y,r)+\phi _{nh}(x,y,r)
674  \label{eq:phi-split}  \label{eq:phi-split}
675  \end{equation}  \end{equation}
676  and write eq(\ref{eq:incompressible}) in the form:  %and write eq(\ref{eq:incompressible}) in the form:
677    %                  ^- this eq is missing (jmc) ; replaced with:
678    and write eq( \ref{eq:horizontal_mtm}) in the form:
679    
680  \begin{equation}  \begin{equation}
681  \frac{\partial \vec{\mathbf{v}_{h}}}{\partial t}+\mathbf{\nabla }_{h}\phi  \frac{\partial \vec{\mathbf{v}_{h}}}{\partial t}+\mathbf{\nabla }_{h}\phi
# Line 716  Grad and div operators in spherical coor Line 770  Grad and div operators in spherical coor
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}
# Line 766  et.al., 1997a. As in \textbf{HPE }only a Line 821  et.al., 1997a. As in \textbf{HPE }only a
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}
# Line 836  stepping forward the horizontal momentum Line 891  stepping forward the horizontal momentum
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
# Line 1025  friction. These coefficients are the sam Line 1080  friction. These coefficients are the sam
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}
# Line 1051  salinity ... ). Line 1106  salinity ... ).
1106    
1107  \subsection{Vector invariant form}  \subsection{Vector invariant form}
1108    
1109  For some purposes it is advantageous to write momentum advection in eq(\ref  For some purposes it is advantageous to write momentum advection in
1110  {eq:horizontal_mtm}) and (\ref{eq:vertical_mtm}) in the (so-called) `vector invariant' form:  eq(\ref {eq:horizontal_mtm}) and (\ref{eq:vertical_mtm}) in the
1111    (so-called) `vector invariant' form:
1112    
1113  \begin{equation}  \begin{equation}
1114  \frac{D\vec{\mathbf{v}}}{Dt}=\frac{\partial \vec{\mathbf{v}}}{\partial t}  \frac{D\vec{\mathbf{v}}}{Dt}=\frac{\partial \vec{\mathbf{v}}}{\partial t}
# Line 1163  In $p$-coordinates, the upper boundary a Line 1219  In $p$-coordinates, the upper boundary a
1219  surface ($\phi $ is imposed and $\omega \neq 0$).  surface ($\phi $ is imposed and $\omega \neq 0$).
1220    
1221  \subsubsection{Splitting the geo-potential}  \subsubsection{Splitting the geo-potential}
1222    \label{sec:hpe-p-geo-potential-split}
1223    
1224  For the purposes of initialization and reducing round-off errors, the model  For the purposes of initialization and reducing round-off errors, the model
1225  deals with perturbations from reference (or ``standard'') profiles. For  deals with perturbations from reference (or ``standard'') profiles. For
# Line 1192  _{o}(p_{o})=g~Z_{topo}$, defined: Line 1249  _{o}(p_{o})=g~Z_{topo}$, defined:
1249  The final form of the HPE's in p coordinates is then:  The final form of the HPE's in p coordinates is then:
1250  \begin{eqnarray}  \begin{eqnarray}
1251  \frac{D\vec{\mathbf{v}}_{h}}{Dt}+f\hat{\mathbf{k}}\times \vec{\mathbf{v}}  \frac{D\vec{\mathbf{v}}_{h}}{Dt}+f\hat{\mathbf{k}}\times \vec{\mathbf{v}}
1252  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \label{eq:atmos-prime} \\  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}}
1253    \label{eq:atmos-prime} \\
1254  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\
1255  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1256  \partial p} &=&0 \\  \partial p} &=&0 \\
# Line 1238  _{\theta ,p}\frac{DS}{Dt}+\left. \frac{\ Line 1296  _{\theta ,p}\frac{DS}{Dt}+\left. \frac{\
1296  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexpansion}  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexpansion}
1297  \end{equation}  \end{equation}
1298    
1299  Note that $\frac{\partial \rho }{\partial p}=\frac{1}{c_{s}^{2}}$ is the  Note that $\frac{\partial \rho }{\partial p}=\frac{1}{c_{s}^{2}}$ is
1300  reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref{eq-zns-cont} gives:  the reciprocal of the sound speed ($c_{s}$) squared. Substituting into
1301    \ref{eq-zns-cont} gives:
1302  \begin{equation}  \begin{equation}
1303  \frac{1}{\rho c_{s}^{2}}\frac{Dp}{Dt}+\mathbf{\nabla }_{z}\cdot \vec{\mathbf{  \frac{1}{\rho c_{s}^{2}}\frac{Dp}{Dt}+\mathbf{\nabla }_{z}\cdot \vec{\mathbf{
1304  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}
# Line 1433  u=r\cos \varphi \frac{D\lambda }{Dt} Line 1492  u=r\cos \varphi \frac{D\lambda }{Dt}
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}
# Line 1445  Here $\varphi $ is the latitude, $\lambd Line 1503  Here $\varphi $ is the latitude, $\lambd
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*}
# Line 1455  spherical coordinates: Line 1513  spherical coordinates:
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*}

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