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# Line 32  Line 32 
32  %tci%\tableofcontents  %tci%\tableofcontents
33    
34    
 \part{MIT GCM basics}  
   
35  % Section: Overview  % Section: Overview
36    
37  % $Header$  This document provides the reader with the information necessary to
 % $Name$  
   
 \section{Introduction}  
   
 This documentation provides the reader with the information necessary to  
38  carry out numerical experiments using MITgcm. It gives a comprehensive  carry out numerical experiments using MITgcm. It gives a comprehensive
39  description of the continuous equations on which the model is based, the  description of the continuous equations on which the model is based, the
40  numerical algorithms the model employs and a description of the associated  numerical algorithms the model employs and a description of the associated
# Line 51  are available. A number of examples illu Line 44  are available. A number of examples illu
44  both process and general circulation studies of the atmosphere and ocean are  both process and general circulation studies of the atmosphere and ocean are
45  also presented.  also presented.
46    
47    \section{Introduction}
48    \begin{rawhtml}
49    <!-- CMIREDIR:innovations: -->
50    \end{rawhtml}
51    
52    
53  MITgcm has a number of novel aspects:  MITgcm has a number of novel aspects:
54    
55  \begin{itemize}  \begin{itemize}
56  \item it can be used to study both atmospheric and oceanic phenomena; one  \item it can be used to study both atmospheric and oceanic phenomena; one
57  hydrodynamical kernel is used to drive forward both atmospheric and oceanic  hydrodynamical kernel is used to drive forward both atmospheric and oceanic
58  models - see fig  models - see fig \ref{fig:onemodel}
 \marginpar{  
 Fig.1 One model}\ref{fig:onemodel}  
59    
60  %% CNHbegin  %% CNHbegin
61  \input{part1/one_model_figure}  \input{s_overview/text/one_model_figure}
62  %% CNHend  %% CNHend
63    
64  \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
65  small-scale and large scale processes - see fig  small-scale and large scale processes - see fig \ref{fig:all-scales}
 \marginpar{  
 Fig.2 All scales}\ref{fig:all-scales}  
66    
67  %% CNHbegin  %% CNHbegin
68  \input{part1/all_scales_figure}  \input{s_overview/text/all_scales_figure}
69  %% CNHend  %% CNHend
70    
71  \item finite volume techniques are employed yielding an intuitive  \item finite volume techniques are employed yielding an intuitive
72  discretization and support for the treatment of irregular geometries using  discretization and support for the treatment of irregular geometries using
73  orthogonal curvilinear grids and shaved cells - see fig  orthogonal curvilinear grids and shaved cells - see fig \ref{fig:finite-volumes}
 \marginpar{  
 Fig.3 Finite volumes}\ref{fig:finite-volumes}  
74    
75  %% CNHbegin  %% CNHbegin
76  \input{part1/fvol_figure}  \input{s_overview/text/fvol_figure}
77  %% CNHend  %% CNHend
78    
79  \item tangent linear and adjoint counterparts are automatically maintained  \item tangent linear and adjoint counterparts are automatically maintained
# Line 91  studies. Line 84  studies.
84  computational platforms.  computational platforms.
85  \end{itemize}  \end{itemize}
86    
87    
88  Key publications reporting on and charting the development of the model are  Key publications reporting on and charting the development of the model are
89  listed in an Appendix.  \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}
90    (an overview on the model formulation can also be found in \cite{adcroft:04c}):
91    
92    \begin{verbatim}
93    Hill, C. and J. Marshall, (1995)
94    Application of a Parallel Navier-Stokes Model to Ocean Circulation in
95    Parallel Computational Fluid Dynamics
96    In Proceedings of Parallel Computational Fluid Dynamics: Implementations
97    and Results Using Parallel Computers, 545-552.
98    Elsevier Science B.V.: New York
99    
100    Marshall, J., C. Hill, L. Perelman, and A. Adcroft, (1997)
101    Hydrostatic, quasi-hydrostatic, and nonhydrostatic ocean modeling
102    J. Geophysical Res., 102(C3), 5733-5752.
103    
104    Marshall, J., A. Adcroft, C. Hill, L. Perelman, and C. Heisey, (1997)
105    A finite-volume, incompressible Navier Stokes model for studies of the ocean
106    on parallel computers,
107    J. Geophysical Res., 102(C3), 5753-5766.
108    
109    Adcroft, A.J., Hill, C.N. and J. Marshall, (1997)
110    Representation of topography by shaved cells in a height coordinate ocean
111    model
112    Mon Wea Rev, vol 125, 2293-2315
113    
114    Marshall, J., Jones, H. and C. Hill, (1998)
115    Efficient ocean modeling using non-hydrostatic algorithms
116    Journal of Marine Systems, 18, 115-134
117    
118    Adcroft, A., Hill C. and J. Marshall: (1999)
119    A new treatment of the Coriolis terms in C-grid models at both high and low
120    resolutions,
121    Mon. Wea. Rev. Vol 127, pages 1928-1936
122    
123    Hill, C, Adcroft,A., Jamous,D., and J. Marshall, (1999)
124    A Strategy for Terascale Climate Modeling.
125    In Proceedings of the Eighth ECMWF Workshop on the Use of Parallel Processors
126    in Meteorology, pages 406-425
127    World Scientific Publishing Co: UK
128    
129    Marotzke, J, Giering,R., Zhang, K.Q., Stammer,D., Hill,C., and T.Lee, (1999)
130    Construction of the adjoint MIT ocean general circulation model and
131    application to Atlantic heat transport variability
132    J. Geophysical Res., 104(C12), 29,529-29,547.
133    
134    \end{verbatim}
135    
136  We begin by briefly showing some of the results of the model in action to  We begin by briefly showing some of the results of the model in action to
137  give a feel for the wide range of problems that can be addressed using it.  give a feel for the wide range of problems that can be addressed using it.
 \pagebreak  
   
 % $Header$  
 % $Name$  
138    
139  \section{Illustrations of the model in action}  \section{Illustrations of the model in action}
140    
141  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,
142  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
143  atmospheric winds - see fig.2\ref{fig:all-scales}. To give a flavor of the  atmospheric winds - see figure \ref{fig:all-scales}. To give a flavor of the
144  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
145  of them here. A more detailed description of the underlying formulation,  of them here. A more detailed description of the underlying formulation,
146  numerical algorithm and implementation that lie behind these calculations is  numerical algorithm and implementation that lie behind these calculations is
147  given later. Indeed many of the illustrative examples shown below can be  given later. Indeed many of the illustrative examples shown below can be
148  easily reproduced: simply download the model (the minimum you need is a PC  easily reproduced: simply download the model (the minimum you need is a PC
149  running linux, together with a FORTRAN\ 77 compiler) and follow the examples  running Linux, together with a FORTRAN\ 77 compiler) and follow the examples
150  described in detail in the documentation.  described in detail in the documentation.
151    
152  \subsection{Global atmosphere: `Held-Suarez' benchmark}  \subsection{Global atmosphere: `Held-Suarez' benchmark}
153    \begin{rawhtml}
154    <!-- CMIREDIR:atmospheric_example: -->
155    \end{rawhtml}
156    
 A novel feature of MITgcm is its ability to simulate both atmospheric and  
 oceanographic flows at both small and large scales.  
157    
158  Fig.E1a.\ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$  
159    A novel feature of MITgcm is its ability to simulate, using one basic algorithm,
160    both atmospheric and oceanographic flows at both small and large scales.
161    
162    Figure \ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$
163  temperature field obtained using the atmospheric isomorph of MITgcm run at  temperature field obtained using the atmospheric isomorph of MITgcm run at
164  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
165  (blue) and warm air along an equatorial band (red). Fully developed  (blue) and warm air along an equatorial band (red). Fully developed
166  baroclinic eddies spawned in the northern hemisphere storm track are  baroclinic eddies spawned in the northern hemisphere storm track are
167  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 131  in Held and Suarez; 1994 designed to tes Line 171  in Held and Suarez; 1994 designed to tes
171  there are no mountains or land-sea contrast.  there are no mountains or land-sea contrast.
172    
173  %% CNHbegin  %% CNHbegin
174  \input{part1/cubic_eddies_figure}  \input{s_overview/text/cubic_eddies_figure}
175  %% CNHend  %% CNHend
176    
177  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
178  globe permitting a uniform gridding and obviated the need to fourier filter.  globe permitting a uniform griding and obviated the need to Fourier filter.
179  The `vector-invariant' form of MITgcm supports any orthogonal curvilinear  The `vector-invariant' form of MITgcm supports any orthogonal curvilinear
180  grid, of which the cubed sphere is just one of many choices.  grid, of which the cubed sphere is just one of many choices.
181    
182  Fig.E1b shows the 5-year mean, zonally averaged potential temperature, zonal  Figure \ref{fig:hs_zave_u} shows the 5-year mean, zonally averaged zonal
183  wind and meridional overturning streamfunction from a 20-level version of  wind from a 20-level configuration of
184  the model. It compares favorable with more conventional spatial  the model. It compares favorable with more conventional spatial
185  discretization approaches.  discretization approaches. The two plots show the field calculated using the
186    cube-sphere grid and the flow calculated using a regular, spherical polar
187  A regular spherical lat-lon grid can also be used.  latitude-longitude grid. Both grids are supported within the model.
188    
189  %% CNHbegin  %% CNHbegin
190  \input{part1/hs_zave_u_figure}  \input{s_overview/text/hs_zave_u_figure}
191  %% CNHend  %% CNHend
192    
193  \subsection{Ocean gyres}  \subsection{Ocean gyres}
194    \begin{rawhtml}
195    <!-- CMIREDIR:oceanic_example: -->
196    \end{rawhtml}
197    \begin{rawhtml}
198    <!-- CMIREDIR:ocean_gyres: -->
199    \end{rawhtml}
200    
201  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
202  atmosphere. Ocean eddies play an important role in modifying the  atmosphere. Ocean eddies play an important role in modifying the
# Line 160  diffusive patterns of ocean currents. Bu Line 206  diffusive patterns of ocean currents. Bu
206  increased until the baroclinic instability process is resolved, numerical  increased until the baroclinic instability process is resolved, numerical
207  solutions of a different and much more realistic kind, can be obtained.  solutions of a different and much more realistic kind, can be obtained.
208    
209  Fig. ?.? shows the surface temperature and velocity field obtained from  Figure \ref{fig:ocean-gyres} shows the surface temperature and
210  MITgcm run at $\frac{1}{6}^{\circ }$ horizontal resolution on a $lat-lon$  velocity field obtained from MITgcm run at $\frac{1}{6}^{\circ }$
211  grid in which the pole has been rotated by 90$^{\circ }$ on to the equator  horizontal resolution on a \textit{lat-lon} grid in which the pole has
212  (to avoid the converging of meridian in northern latitudes). 21 vertical  been rotated by $90^{\circ }$ on to the equator (to avoid the
213  levels are used in the vertical with a `lopped cell' representation of  converging of meridian in northern latitudes). 21 vertical levels are
214  topography. The development and propagation of anomalously warm and cold  used in the vertical with a `lopped cell' representation of
215  eddies can be clearly been seen in the Gulf Stream region. The transport of  topography. The development and propagation of anomalously warm and
216  warm water northward by the mean flow of the Gulf Stream is also clearly  cold eddies can be clearly seen in the Gulf Stream region. The
217  visible.  transport of warm water northward by the mean flow of the Gulf Stream
218    is also clearly visible.
219    
220  %% CNHbegin  %% CNHbegin
221  \input{part1/ocean_gyres_figure}  \input{s_overview/text/atl6_figure}
222  %% CNHend  %% CNHend
223    
224    
225  \subsection{Global ocean circulation}  \subsection{Global ocean circulation}
226    \begin{rawhtml}
227    <!-- CMIREDIR:global_ocean_circulation: -->
228    \end{rawhtml}
229    
230    Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean
231    currents at the surface of a $4^{\circ }$ global ocean model run with
232    15 vertical levels. Lopped cells are used to represent topography on a
233    regular \textit{lat-lon} grid extending from $70^{\circ }N$ to
234    $70^{\circ }S$. The model is driven using monthly-mean winds with
235    mixed boundary conditions on temperature and salinity at the surface.
236    The transfer properties of ocean eddies, convection and mixing is
237    parameterized in this model.
238    
239  Fig.E2a shows the pattern of ocean currents at the surface of a 4$^{\circ }$  Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning
240  global ocean model run with 15 vertical levels. Lopped cells are used to  circulation of the global ocean in Sverdrups.
 represent topography on a regular $lat-lon$ grid extending from 70$^{\circ  
 }N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with  
 mixed boundary conditions on temperature and salinity at the surface. The  
 transfer properties of ocean eddies, convection and mixing is parameterized  
 in this model.  
   
 Fig.E2b shows the meridional overturning circulation of the global ocean in  
 Sverdrups.  
241    
242  %%CNHbegin  %%CNHbegin
243  \input{part1/global_circ_figure}  \input{s_overview/text/global_circ_figure}
244  %%CNHend  %%CNHend
245    
246  \subsection{Convection and mixing over topography}  \subsection{Convection and mixing over topography}
247    \begin{rawhtml}
248    <!-- CMIREDIR:mixing_over_topography: -->
249    \end{rawhtml}
250    
251    
252  Dense plumes generated by localized cooling on the continental shelf of the  Dense plumes generated by localized cooling on the continental shelf of the
253  ocean may be influenced by rotation when the deformation radius is smaller  ocean may be influenced by rotation when the deformation radius is smaller
254  than the width of the cooling region. Rather than gravity plumes, the  than the width of the cooling region. Rather than gravity plumes, the
255  mechanism for moving dense fluid down the shelf is then through geostrophic  mechanism for moving dense fluid down the shelf is then through geostrophic
256  eddies. The simulation shown in the figure (blue is cold dense fluid, red is  eddies. The simulation shown in the figure \ref{fig:convect-and-topo}
257    (blue is cold dense fluid, red is
258  warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to  warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to
259  trigger convection by surface cooling. The cold, dense water falls down the  trigger convection by surface cooling. The cold, dense water falls down the
260  slope but is deflected along the slope by rotation. It is found that  slope but is deflected along the slope by rotation. It is found that
# Line 207  strong, and replaced by lateral entrainm Line 263  strong, and replaced by lateral entrainm
263  instability of the along-slope current.  instability of the along-slope current.
264    
265  %%CNHbegin  %%CNHbegin
266  \input{part1/convect_and_topo}  \input{s_overview/text/convect_and_topo}
267  %%CNHend  %%CNHend
268    
269  \subsection{Boundary forced internal waves}  \subsection{Boundary forced internal waves}
270    \begin{rawhtml}
271    <!-- CMIREDIR:boundary_forced_internal_waves: -->
272    \end{rawhtml}
273    
274  The unique ability of MITgcm to treat non-hydrostatic dynamics in the  The unique ability of MITgcm to treat non-hydrostatic dynamics in the
275  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
276  dynamics and mixing in oceanic canyons and ridges driven by large amplitude  dynamics and mixing in oceanic canyons and ridges driven by large amplitude
277  barotropic tidal currents imposed through open boundary conditions.  barotropic tidal currents imposed through open boundary conditions.
278    
279  Fig. ?.? shows the influence of cross-slope topographic variations on  Fig. \ref{fig:boundary-forced-wave} shows the influence of cross-slope
280    topographic variations on
281  internal wave breaking - the cross-slope velocity is in color, the density  internal wave breaking - the cross-slope velocity is in color, the density
282  contoured. The internal waves are excited by application of open boundary  contoured. The internal waves are excited by application of open boundary
283  conditions on the left.\ They propagate to the sloping boundary (represented  conditions on the left. They propagate to the sloping boundary (represented
284  using MITgcm's finite volume spatial discretization) where they break under  using MITgcm's finite volume spatial discretization) where they break under
285  nonhydrostatic dynamics.  nonhydrostatic dynamics.
286    
287  %%CNHbegin  %%CNHbegin
288  \input{part1/boundary_forced_waves}  \input{s_overview/text/boundary_forced_waves}
289  %%CNHend  %%CNHend
290    
291  \subsection{Parameter sensitivity using the adjoint of MITgcm}  \subsection{Parameter sensitivity using the adjoint of MITgcm}
292    \begin{rawhtml}
293    <!-- CMIREDIR:parameter_sensitivity: -->
294    \end{rawhtml}
295    
296  Forward and tangent linear counterparts of MITgcm are supported using an  Forward and tangent linear counterparts of MITgcm are supported using an
297  `automatic adjoint compiler'. These can be used in parameter sensitivity and  `automatic adjoint compiler'. These can be used in parameter sensitivity and
298  data assimilation studies.  data assimilation studies.
299    
300  As one example of application of the MITgcm adjoint, Fig.E4 maps the  As one example of application of the MITgcm adjoint, Figure
301  gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude  \ref{fig:hf-sensitivity} maps the gradient $\frac{\partial J}{\partial
302  of the overturning streamfunction shown in fig?.? at 40$^{\circ }$N and $    \mathcal{H}}$where $J$ is the magnitude of the overturning
303  \mathcal{H}$ is the air-sea heat flux 100 years before. We see that $J$ is  stream-function shown in figure \ref{fig:large-scale-circ} at
304  sensitive to heat fluxes over the Labrador Sea, one of the important sources  $60^{\circ }N$ and $ \mathcal{H}(\lambda,\varphi)$ is the mean, local
305  of deep water for the thermohaline circulations. This calculation also  air-sea heat flux over a 100 year period. We see that $J$ is sensitive
306    to heat fluxes over the Labrador Sea, one of the important sources of
307    deep water for the thermohaline circulations. This calculation also
308  yields sensitivities to all other model parameters.  yields sensitivities to all other model parameters.
309    
310  %%CNHbegin  %%CNHbegin
311  \input{part1/adj_hf_ocean_figure}  \input{s_overview/text/adj_hf_ocean_figure}
312  %%CNHend  %%CNHend
313    
314  \subsection{Global state estimation of the ocean}  \subsection{Global state estimation of the ocean}
315    \begin{rawhtml}
316    <!-- CMIREDIR:global_state_estimation: -->
317    \end{rawhtml}
318    
319    
320  An important application of MITgcm is in state estimation of the global  An important application of MITgcm is in state estimation of the global
321  ocean circulation. An appropriately defined `cost function', which measures  ocean circulation. An appropriately defined `cost function', which measures
322  the departure of the model from observations (both remotely sensed and  the departure of the model from observations (both remotely sensed and
323  insitu) over an interval of time, is minimized by adjusting `control  in-situ) over an interval of time, is minimized by adjusting `control
324  parameters' such as air-sea fluxes, the wind field, the initial conditions  parameters' such as air-sea fluxes, the wind field, the initial conditions
325  etc. Figure ?.? shows an estimate of the time-mean surface elevation of the  etc. Figure \ref{fig:assimilated-globes} shows the large scale planetary
326  ocean obtained by bringing the model in to consistency with altimetric and  circulation and a Hopf-Muller plot of Equatorial sea-surface height.
327  in-situ observations over the period 1992-1997.  Both are obtained from assimilation bringing the model in to
328    consistency with altimetric and in-situ observations over the period
329    1992-1997.
330    
331  %% CNHbegin  %% CNHbegin
332  \input{part1/globes_figure}  \input{s_overview/text/assim_figure}
333  %% CNHend  %% CNHend
334    
335  \subsection{Ocean biogeochemical cycles}  \subsection{Ocean biogeochemical cycles}
336    \begin{rawhtml}
337  MITgcm is being used to study global biogeochemical cycles in the ocean. For  <!-- CMIREDIR:ocean_biogeo_cycles: -->
338  example one can study the effects of interannual changes in meteorological  \end{rawhtml}
339  forcing and upper ocean circulation on the fluxes of carbon dioxide and  
340  oxygen between the ocean and atmosphere. The figure shows the annual air-sea  MITgcm is being used to study global biogeochemical cycles in the
341  flux of oxygen and its relation to density outcrops in the southern oceans  ocean. For example one can study the effects of interannual changes in
342  from a single year of a global, interannually varying simulation.  meteorological forcing and upper ocean circulation on the fluxes of
343    carbon dioxide and oxygen between the ocean and atmosphere. Figure
344    \ref{fig:biogeo} shows the annual air-sea flux of oxygen and its
345    relation to density outcrops in the southern oceans from a single year
346    of a global, interannually varying simulation. The simulation is run
347    at $1^{\circ}\times1^{\circ}$ resolution telescoping to
348    $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not
349    shown).
350    
351  %%CNHbegin  %%CNHbegin
352  \input{part1/biogeo_figure}  \input{s_overview/text/biogeo_figure}
353  %%CNHend  %%CNHend
354    
355  \subsection{Simulations of laboratory experiments}  \subsection{Simulations of laboratory experiments}
356    \begin{rawhtml}
357    <!-- CMIREDIR:classroom_exp: -->
358    \end{rawhtml}
359    
360  Figure ?.? shows MITgcm being used to simulate a laboratory experiment  Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a
361  enquiring in to the dynamics of the Antarctic Circumpolar Current (ACC). An  laboratory experiment inquiring into the dynamics of the Antarctic Circumpolar Current (ACC). An
362  initially homogeneous tank of water ($1m$ in diameter) is driven from its  initially homogeneous tank of water ($1m$ in diameter) is driven from its
363  free surface by a rotating heated disk. The combined action of mechanical  free surface by a rotating heated disk. The combined action of mechanical
364  and thermal forcing creates a lens of fluid which becomes baroclinically  and thermal forcing creates a lens of fluid which becomes baroclinically
365  unstable. The stratification and depth of penetration of the lens is  unstable. The stratification and depth of penetration of the lens is
366  arrested by its instability in a process analogous to that whic sets the  arrested by its instability in a process analogous to that which sets the
367  stratification of the ACC.  stratification of the ACC.
368    
369  %%CNHbegin  %%CNHbegin
370  \input{part1/lab_figure}  \input{s_overview/text/lab_figure}
371  %%CNHend  %%CNHend
372    
 % $Header$  
 % $Name$  
   
373  \section{Continuous equations in `r' coordinates}  \section{Continuous equations in `r' coordinates}
374    \begin{rawhtml}
375    <!-- CMIREDIR:z-p_isomorphism: -->
376    \end{rawhtml}
377    
378  To render atmosphere and ocean models from one dynamical core we exploit  To render atmosphere and ocean models from one dynamical core we exploit
379  `isomorphisms' between equation sets that govern the evolution of the  `isomorphisms' between equation sets that govern the evolution of the
380  respective fluids - see fig.4  respective fluids - see figure \ref{fig:isomorphic-equations}.
381  \marginpar{  One system of hydrodynamical equations is written down
 Fig.4. Isomorphisms}. One system of hydrodynamical equations is written down  
382  and encoded. The model variables have different interpretations depending on  and encoded. The model variables have different interpretations depending on
383  whether the atmosphere or ocean is being studied. Thus, for example, the  whether the atmosphere or ocean is being studied. Thus, for example, the
384  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are
385  modeling the atmosphere and height, $z$, if we are modeling the ocean.  modeling the atmosphere (right hand side of figure \ref{fig:isomorphic-equations})
386    and height, $z$, if we are modeling the ocean (left hand side of figure
387    \ref{fig:isomorphic-equations}).
388    
389  %%CNHbegin  %%CNHbegin
390  \input{part1/zandpcoord_figure.tex}  \input{s_overview/text/zandpcoord_figure.tex}
391  %%CNHend  %%CNHend
392    
393  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 314  velocity $\vec{\mathbf{v}}$, active trac Line 396  velocity $\vec{\mathbf{v}}$, active trac
396  depend on $\theta $, $S$, and $p$. The equations that govern the evolution  depend on $\theta $, $S$, and $p$. The equations that govern the evolution
397  of these fields, obtained by applying the laws of classical mechanics and  of these fields, obtained by applying the laws of classical mechanics and
398  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of
399  a generic vertical coordinate, $r$, see fig.5  a generic vertical coordinate, $r$, so that the appropriate
400  \marginpar{  kinematic boundary conditions can be applied isomorphically
401  Fig.5 The vertical coordinate of model}:  see figure \ref{fig:zandp-vert-coord}.
402    
403  %%CNHbegin  %%CNHbegin
404  \input{part1/vertcoord_figure.tex}  \input{s_overview/text/vertcoord_figure.tex}
405  %%CNHend  %%CNHend
406    
407  \begin{equation*}  \begin{equation}
408  \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}}
409  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}
410  \text{ horizontal mtm}  \text{ horizontal mtm} \label{eq:horizontal_mtm}
411  \end{equation*}  \end{equation}
412    
413  \begin{equation*}  \begin{equation}
414  \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{
415  v}}\right) +\frac{\partial \phi }{\partial r}+b=\mathcal{F}_{\dot{r}}\text{  v}}\right) +\frac{\partial \phi }{\partial r}+b=\mathcal{F}_{\dot{r}}\text{
416  vertical mtm}  vertical mtm} \label{eq:vertical_mtm}
417  \end{equation*}  \end{equation}
418    
419  \begin{equation}  \begin{equation}
420  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{
421  \partial r}=0\text{ continuity}  \label{eq:continuous}  \partial r}=0\text{ continuity}  \label{eq:continuity}
422  \end{equation}  \end{equation}
423    
424  \begin{equation*}  \begin{equation}
425  b=b(\theta ,S,r)\text{ equation of state}  b=b(\theta ,S,r)\text{ equation of state} \label{eq:equation_of_state}
426  \end{equation*}  \end{equation}
427    
428  \begin{equation*}  \begin{equation}
429  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature}  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature}
430  \end{equation*}  \label{eq:potential_temperature}
431    \end{equation}
432    
433  \begin{equation*}  \begin{equation}
434  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity}  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity}
435  \end{equation*}  \label{eq:humidity_salt}
436    \end{equation}
437    
438  Here:  Here:
439    
# Line 413  S\text{ is specific humidity in the atmo Line 497  S\text{ is specific humidity in the atmo
497  \end{equation*}  \end{equation*}
498    
499  The $\mathcal{F}^{\prime }s$ and $\mathcal{Q}^{\prime }s$ are provided by  The $\mathcal{F}^{\prime }s$ and $\mathcal{Q}^{\prime }s$ are provided by
500  extensive `physics' packages for atmosphere and ocean described in Chapter 6.  `physics' and forcing packages for atmosphere and ocean. These are described
501    in later chapters.
502    
503  \subsection{Kinematic Boundary conditions}  \subsection{Kinematic Boundary conditions}
504    
505  \subsubsection{vertical}  \subsubsection{vertical}
506    
507  at fixed and moving $r$ surfaces we set (see fig.5):  at fixed and moving $r$ surfaces we set (see figure \ref{fig:zandp-vert-coord}):
508    
509  \begin{equation}  \begin{equation}
510  \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)}
511  \label{eq:fixedbc}  \label{eq:fixedbc}
512  \end{equation}  \end{equation}
513    
514  \begin{equation}  \begin{equation}
515  \dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \  \dot{r}=\frac{Dr}{Dt} \text{\ at\ } r=R_{moving}\text{ \
516  (oceansurface,bottomoftheatmosphere)}  \label{eq:movingbc}  (ocean surface,bottom of the atmosphere)}  \label{eq:movingbc}
517  \end{equation}  \end{equation}
518    
519  Here  Here
# Line 450  where $\vec{\mathbf{n}}$ is the normal t Line 535  where $\vec{\mathbf{n}}$ is the normal t
535    
536  \subsection{Atmosphere}  \subsection{Atmosphere}
537    
538  In the atmosphere, see fig.5, we interpret:  In the atmosphere, (see figure \ref{fig:zandp-vert-coord}), we interpret:
539    
540  \begin{equation}  \begin{equation}
541  r=p\text{ is the pressure}  \label{eq:atmos-r}  r=p\text{ is the pressure}  \label{eq:atmos-r}
# Line 521  The boundary conditions at top and botto Line 606  The boundary conditions at top and botto
606  atmosphere)}  \label{eq:moving-bc-atmos}  atmosphere)}  \label{eq:moving-bc-atmos}
607  \end{eqnarray}  \end{eqnarray}
608    
609  Then the (hydrostatic form of) eq(\ref{eq:continuous}) yields a consistent  Then the (hydrostatic form of) equations
610  set of atmospheric equations which, for convenience, are written out in $p$  (\ref{eq:horizontal_mtm}-\ref{eq:humidity_salt}) yields a consistent
611  coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}).  set of atmospheric equations which, for convenience, are written out
612    in $p$ coordinates in Appendix Atmosphere - see
613    eqs(\ref{eq:atmos-prime}).
614    
615  \subsection{Ocean}  \subsection{Ocean}
616    
# Line 558  w &=&\frac{D\eta }{Dt}\text{ at }r=R_{mo Line 645  w &=&\frac{D\eta }{Dt}\text{ at }r=R_{mo
645  \end{eqnarray}  \end{eqnarray}
646  where $\eta $ is the elevation of the free surface.  where $\eta $ is the elevation of the free surface.
647    
648  Then eq(\ref{eq:continuous}) yields a consistent set of oceanic equations  Then equations (\ref{eq:horizontal_mtm}-\ref{eq:humidity_salt}) yield a consistent set
649    of oceanic equations
650  which, for convenience, are written out in $z$ coordinates in Appendix Ocean  which, for convenience, are written out in $z$ coordinates in Appendix Ocean
651  - see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}).  - see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}).
652    
653  \subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and  \subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and
654  Non-hydrostatic forms}  Non-hydrostatic forms}
655    \label{sec:all_hydrostatic_forms}
656    \begin{rawhtml}
657    <!-- CMIREDIR:non_hydrostatic: -->
658    \end{rawhtml}
659    
660    
661  Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms:  Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms:
662    
# Line 571  Let us separate $\phi $ in to surface, h Line 664  Let us separate $\phi $ in to surface, h
664  \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)
665  \label{eq:phi-split}  \label{eq:phi-split}
666  \end{equation}  \end{equation}
667  and write eq(\ref{incompressible}a,b) in the form:  %and write eq(\ref{eq:incompressible}) in the form:
668    %                  ^- this eq is missing (jmc) ; replaced with:
669    and write eq( \ref{eq:horizontal_mtm}) in the form:
670    
671  \begin{equation}  \begin{equation}
672  \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 604  discussion: Line 699  discussion:
699  \left.  \left.
700  \begin{tabular}{l}  \begin{tabular}{l}
701  $G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\  $G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\
702  $-\left\{ \underline{\frac{u\dot{r}}{{r}}}-\frac{uv\tan lat}{{r}}\right\} $  $-\left\{ \underline{\frac{u\dot{r}}{{r}}}-\frac{uv\tan \varphi}{{r}}\right\} $
703  \\  \\
704  $-\left\{ -2\Omega v\sin lat+\underline{2\Omega \dot{r}\cos lat}\right\} $  $-\left\{ -2\Omega v\sin \varphi+\underline{2\Omega \dot{r}\cos \varphi}\right\} $
705  \\  \\
706  $+\mathcal{F}_{u}$  $+\mathcal{F}_{u}$
707  \end{tabular}  \end{tabular}
# Line 624  $+\mathcal{F}_{u}$ Line 719  $+\mathcal{F}_{u}$
719  \left.  \left.
720  \begin{tabular}{l}  \begin{tabular}{l}
721  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\
722  $-\left\{ \underline{\frac{v\dot{r}}{{r}}}-\frac{u^{2}\tan lat}{{r}}\right\}  $-\left\{ \underline{\frac{v\dot{r}}{{r}}}-\frac{u^{2}\tan \varphi}{{r}}\right\}
723  $ \\  $ \\
724  $-\left\{ -2\Omega u\sin lat\right\} $ \\  $-\left\{ -2\Omega u\sin \varphi \right\} $ \\
725  $+\mathcal{F}_{v}$  $+\mathcal{F}_{v}$
726  \end{tabular}  \end{tabular}
727  \ \right\} \left\{  \ \right\} \left\{
# Line 645  $+\mathcal{F}_{v}$ Line 740  $+\mathcal{F}_{v}$
740  \begin{tabular}{l}  \begin{tabular}{l}
741  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\
742  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\
743  ${+}\underline{{2\Omega u\cos lat}}$ \\  ${+}\underline{{2\Omega u\cos \varphi}}$ \\
744  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$
745  \end{tabular}  \end{tabular}
746  \ \right\} \left\{  \ \right\} \left\{
# Line 659  $\underline{\underline{\mathcal{F}_{\dot Line 754  $\underline{\underline{\mathcal{F}_{\dot
754  \end{equation}  \end{equation}
755  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
756    
757  In the above `${r}$' is the distance from the center of the earth and `$lat$  In the above `${r}$' is the distance from the center of the earth and `$\varphi$
758  ' is latitude.  ' is latitude.
759    
760  Grad and div operators in spherical coordinates are defined in appendix  Grad and div operators in spherical coordinates are defined in appendix
761  OPERATORS.  OPERATORS.
 \marginpar{  
 Fig.6 Spherical polar coordinate system.}  
762    
763  %%CNHbegin  %%CNHbegin
764  \input{part1/sphere_coord_figure.tex}  \input{s_overview/text/sphere_coord_figure.tex}
765  %%CNHend  %%CNHend
766    
767  \subsubsection{Shallow atmosphere approximation}  \subsubsection{Shallow atmosphere approximation}
768    
769  Most models are based on the `hydrostatic primitive equations' (HPE's) in  Most models are based on the `hydrostatic primitive equations' (HPE's)
770  which the vertical momentum equation is reduced to a statement of  in which the vertical momentum equation is reduced to a statement of
771  hydrostatic balance and the `traditional approximation' is made in which the  hydrostatic balance and the `traditional approximation' is made in
772  Coriolis force is treated approximately and the shallow atmosphere  which the Coriolis force is treated approximately and the shallow
773  approximation is made.\ The MITgcm need not make the `traditional  atmosphere approximation is made.  MITgcm need not make the
774  approximation'. To be able to support consistent non-hydrostatic forms the  `traditional approximation'. To be able to support consistent
775  shallow atmosphere approximation can be relaxed - when dividing through by $  non-hydrostatic forms the shallow atmosphere approximation can be
776  r $ in, for example, (\ref{eq:gu-speherical}), we do not replace $r$ by $a$,  relaxed - when dividing through by $ r $ in, for example,
777  the radius of the earth.  (\ref{eq:gu-speherical}), we do not replace $r$ by $a$, the radius of
778    the earth.
779    
780  \subsubsection{Hydrostatic and quasi-hydrostatic forms}  \subsubsection{Hydrostatic and quasi-hydrostatic forms}
781    \label{sec:hydrostatic_and_quasi-hydrostatic_forms}
782    
783  These are discussed at length in Marshall et al (1997a).  These are discussed at length in Marshall et al (1997a).
784    
# Line 697  computed at all other levels by integrat Line 792  computed at all other levels by integrat
792    
793  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between
794  gravity and vertical pressure gradients is not imposed. The $2\Omega u\cos  gravity and vertical pressure gradients is not imposed. The $2\Omega u\cos
795  \phi $ Coriolis term are not neglected and are balanced by a non-hydrostatic  \varphi $ Coriolis term are not neglected and are balanced by a non-hydrostatic
796  contribution to the pressure field: only the terms underlined twice in Eqs. (  contribution to the pressure field: only the terms underlined twice in Eqs. (
797  \ref{eq:gu-speherical}$\rightarrow $\ \ref{eq:gw-spherical}) are set to zero  \ref{eq:gu-speherical}$\rightarrow $\ \ref{eq:gw-spherical}) are set to zero
798  and, simultaneously, the shallow atmosphere approximation is relaxed. In  and, simultaneously, the shallow atmosphere approximation is relaxed. In
# Line 706  variation of the radial position of a pa Line 801  variation of the radial position of a pa
801  vertical momentum equation (\ref{eq:mom-w}) becomes:  vertical momentum equation (\ref{eq:mom-w}) becomes:
802    
803  \begin{equation*}  \begin{equation*}
804  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos \varphi
805  \end{equation*}  \end{equation*}
806  making a small correction to the hydrostatic pressure.  making a small correction to the hydrostatic pressure.
807    
# Line 717  et.al., 1997a. As in \textbf{HPE }only a Line 812  et.al., 1997a. As in \textbf{HPE }only a
812    
813  \subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms}  \subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms}
814    
815  The MIT model presently supports a full non-hydrostatic ocean isomorph, but  MITgcm presently supports a full non-hydrostatic ocean isomorph, but
816  only a quasi-non-hydrostatic atmospheric isomorph.  only a quasi-non-hydrostatic atmospheric isomorph.
817    
818  \paragraph{Non-hydrostatic Ocean}  \paragraph{Non-hydrostatic Ocean}
# Line 727  In the non-hydrostatic ocean model all t Line 822  In the non-hydrostatic ocean model all t
822  three dimensional elliptic equation must be solved subject to Neumann  three dimensional elliptic equation must be solved subject to Neumann
823  boundary conditions (see below). It is important to note that use of the  boundary conditions (see below). It is important to note that use of the
824  full \textbf{NH} does not admit any new `fast' waves in to the system - the  full \textbf{NH} does not admit any new `fast' waves in to the system - the
825  incompressible condition eq(\ref{eq:continuous})c has already filtered out  incompressible condition eq(\ref{eq:continuity}) has already filtered out
826  acoustic modes. It does, however, ensure that the gravity waves are treated  acoustic modes. It does, however, ensure that the gravity waves are treated
827  accurately with an exact dispersion relation. The \textbf{NH} set has a  accurately with an exact dispersion relation. The \textbf{NH} set has a
828  complete angular momentum principle and consistent energetics - see White  complete angular momentum principle and consistent energetics - see White
# Line 776  coordinates are supported - see eqs(\ref Line 871  coordinates are supported - see eqs(\ref
871  \subsection{Solution strategy}  \subsection{Solution strategy}
872    
873  The method of solution employed in the \textbf{HPE}, \textbf{QH} and \textbf{  The method of solution employed in the \textbf{HPE}, \textbf{QH} and \textbf{
874  NH} models is summarized in Fig.7.  NH} models is summarized in Figure \ref{fig:solution-strategy}.
875  \marginpar{  Under all dynamics, a 2-d elliptic equation is
 Fig.7 Solution strategy} Under all dynamics, a 2-d elliptic equation is  
876  first solved to find the surface pressure and the hydrostatic pressure at  first solved to find the surface pressure and the hydrostatic pressure at
877  any level computed from the weight of fluid above. Under \textbf{HPE} and  any level computed from the weight of fluid above. Under \textbf{HPE} and
878  \textbf{QH} dynamics, the horizontal momentum equations are then stepped  \textbf{QH} dynamics, the horizontal momentum equations are then stepped
# Line 788  stepping forward the horizontal momentum Line 882  stepping forward the horizontal momentum
882  stepping forward the vertical momentum equation.  stepping forward the vertical momentum equation.
883    
884  %%CNHbegin  %%CNHbegin
885  \input{part1/solution_strategy_figure.tex}  \input{s_overview/text/solution_strategy_figure.tex}
886  %%CNHend  %%CNHend
887    
888  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
889  course, some complication that goes with the inclusion of $\cos \phi \ $  course, some complication that goes with the inclusion of $\cos \varphi \ $
890  Coriolis terms and the relaxation of the shallow atmosphere approximation.  Coriolis terms and the relaxation of the shallow atmosphere approximation.
891  But this leads to negligible increase in computation. In \textbf{NH}, in  But this leads to negligible increase in computation. In \textbf{NH}, in
892  contrast, one additional elliptic equation - a three-dimensional one - must  contrast, one additional elliptic equation - a three-dimensional one - must
# Line 802  Marshall et al, 1997) resulting in a non Line 896  Marshall et al, 1997) resulting in a non
896  hydrostatic limit, is as computationally economic as the \textbf{HPEs}.  hydrostatic limit, is as computationally economic as the \textbf{HPEs}.
897    
898  \subsection{Finding the pressure field}  \subsection{Finding the pressure field}
899    \label{sec:finding_the_pressure_field}
900    
901  Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the  Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the
902  pressure field must be obtained diagnostically. We proceed, as before, by  pressure field must be obtained diagnostically. We proceed, as before, by
# Line 834  atmospheric pressure pushing down on the Line 929  atmospheric pressure pushing down on the
929    
930  \subsubsection{Surface pressure}  \subsubsection{Surface pressure}
931    
932  The surface pressure equation can be obtained by integrating continuity, (  The surface pressure equation can be obtained by integrating continuity,
933  \ref{eq:continuous})c, vertically from $r=R_{fixed}$ to $r=R_{moving}$  (\ref{eq:continuity}), vertically from $r=R_{fixed}$ to $r=R_{moving}$
934    
935  \begin{equation*}  \begin{equation*}
936  \int_{R_{fixed}}^{R_{moving}}\left( \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}  \int_{R_{fixed}}^{R_{moving}}\left( \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}
# Line 860  r $. The above can be rearranged to yiel Line 955  r $. The above can be rearranged to yiel
955  where we have incorporated a source term.  where we have incorporated a source term.
956    
957  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential
958  (atmospheric model), in (\ref{mtm-split}), the horizontal gradient term can  (atmospheric model), in (\ref{eq:mom-h}), the horizontal gradient term can
959  be written  be written
960  \begin{equation}  \begin{equation}
961  \mathbf{\nabla }_{h}\phi _{s}=\mathbf{\nabla }_{h}\left( b_{s}\eta \right)  \mathbf{\nabla }_{h}\phi _{s}=\mathbf{\nabla }_{h}\left( b_{s}\eta \right)
# Line 868  be written Line 963  be written
963  \end{equation}  \end{equation}
964  where $b_{s}$ is the buoyancy at the surface.  where $b_{s}$ is the buoyancy at the surface.
965    
966  In the hydrostatic limit ($\epsilon _{nh}=0$), Eqs(\ref{eq:mom-h}), (\ref  In the hydrostatic limit ($\epsilon _{nh}=0$), equations (\ref{eq:mom-h}), (\ref
967  {eq:free-surface}) and (\ref{eq:phi-surf}) can be solved by inverting a 2-d  {eq:free-surface}) and (\ref{eq:phi-surf}) can be solved by inverting a 2-d
968  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free
969  surface' and `rigid lid' approaches are available.  surface' and `rigid lid' approaches are available.
970    
971  \subsubsection{Non-hydrostatic pressure}  \subsubsection{Non-hydrostatic pressure}
972    
973  Taking the horizontal divergence of (\ref{hor-mtm}) and adding $\frac{  Taking the horizontal divergence of (\ref{eq:mom-h}) and adding
974  \partial }{\partial r}$ of (\ref{vertmtm}), invoking the continuity equation  $\frac{\partial }{\partial r}$ of (\ref{eq:mom-w}), invoking the continuity equation
975  (\ref{incompressible}), we deduce that:  (\ref{eq:continuity}), we deduce that:
976    
977  \begin{equation}  \begin{equation}
978  \nabla _{3}^{2}\phi _{nh}=\nabla .\vec{\mathbf{G}}_{\vec{v}}-\left( \mathbf{  \nabla _{3}^{2}\phi _{nh}=\nabla .\vec{\mathbf{G}}_{\vec{v}}-\left( \mathbf{
# Line 907  tangential component of velocity, $v_{T} Line 1002  tangential component of velocity, $v_{T}
1002  depending on the form chosen for the dissipative terms in the momentum  depending on the form chosen for the dissipative terms in the momentum
1003  equations - see below.  equations - see below.
1004    
1005  Eq.(\ref{nonormalflow}) implies, making use of (\ref{mtm-split}), that:  Eq.(\ref{nonormalflow}) implies, making use of (\ref{eq:mom-h}), that:
1006    
1007  \begin{equation}  \begin{equation}
1008  \widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}}  \widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}}
# Line 947  If the flow is `close' to hydrostatic ba Line 1042  If the flow is `close' to hydrostatic ba
1042  converges rapidly because $\phi _{nh}\ $is then only a small correction to  converges rapidly because $\phi _{nh}\ $is then only a small correction to
1043  the hydrostatic pressure field (see the discussion in Marshall et al, a,b).  the hydrostatic pressure field (see the discussion in Marshall et al, a,b).
1044    
1045  The solution $\phi _{nh}\ $to (\ref{eq:3d-invert}) and (\ref{homneuman})  The solution $\phi _{nh}\ $to (\ref{eq:3d-invert}) and (\ref{eq:inhom-neumann-nh})
1046  does not vanish at $r=R_{moving}$, and so refines the pressure there.  does not vanish at $r=R_{moving}$, and so refines the pressure there.
1047    
1048  \subsection{Forcing/dissipation}  \subsection{Forcing/dissipation}
# Line 955  does not vanish at $r=R_{moving}$, and s Line 1050  does not vanish at $r=R_{moving}$, and s
1050  \subsubsection{Forcing}  \subsubsection{Forcing}
1051    
1052  The forcing terms $\mathcal{F}$ on the rhs of the equations are provided by  The forcing terms $\mathcal{F}$ on the rhs of the equations are provided by
1053  `physics packages' described in detail in chapter ??.  `physics packages' and forcing packages. These are described later on.
1054    
1055  \subsubsection{Dissipation}  \subsubsection{Dissipation}
1056    
# Line 976  friction. These coefficients are the sam Line 1071  friction. These coefficients are the sam
1071    
1072  The mixing terms for the temperature and salinity equations have a similar  The mixing terms for the temperature and salinity equations have a similar
1073  form to that of momentum except that the diffusion tensor can be  form to that of momentum except that the diffusion tensor can be
1074  non-diagonal and have varying coefficients. $\qquad $  non-diagonal and have varying coefficients.
1075  \begin{equation}  \begin{equation}
1076  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
1077  _{h}^{4}(T,S)  \label{eq:diffusion}  _{h}^{4}(T,S)  \label{eq:diffusion}
# Line 1002  salinity ... ). Line 1097  salinity ... ).
1097    
1098  \subsection{Vector invariant form}  \subsection{Vector invariant form}
1099    
1100  For some purposes it is advantageous to write momentum advection in eq(\ref  For some purposes it is advantageous to write momentum advection in
1101  {hor-mtm}) and (\ref{vertmtm}) in the (so-called) `vector invariant' form:  eq(\ref {eq:horizontal_mtm}) and (\ref{eq:vertical_mtm}) in the
1102    (so-called) `vector invariant' form:
1103    
1104  \begin{equation}  \begin{equation}
1105  \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 1021  to discretize the model. Line 1117  to discretize the model.
1117    
1118  \subsection{Adjoint}  \subsection{Adjoint}
1119    
1120  Tangent linear and adjoint counterparts of the forward model and described  Tangent linear and adjoint counterparts of the forward model are described
1121  in Chapter 5.  in Chapter 5.
1122    
 % $Header$  
 % $Name$  
   
1123  \section{Appendix ATMOSPHERE}  \section{Appendix ATMOSPHERE}
1124    
1125  \subsection{Hydrostatic Primitive Equations for the Atmosphere in pressure  \subsection{Hydrostatic Primitive Equations for the Atmosphere in pressure
# Line 1046  p\alpha &=&RT  \label{eq:atmos-eos} \\ Line 1139  p\alpha &=&RT  \label{eq:atmos-eos} \\
1139  c_{v}\frac{DT}{Dt}+p\frac{D\alpha }{Dt} &=&\mathcal{Q}  \label{eq:atmos-heat}  c_{v}\frac{DT}{Dt}+p\frac{D\alpha }{Dt} &=&\mathcal{Q}  \label{eq:atmos-heat}
1140  \end{eqnarray}  \end{eqnarray}
1141  where $\vec{\mathbf{v}}_{h}=(u,v,0)$ is the `horizontal' (on pressure  where $\vec{\mathbf{v}}_{h}=(u,v,0)$ is the `horizontal' (on pressure
1142  surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot  surfaces) component of velocity, $\frac{D}{Dt}=\frac{\partial}{\partial t}
1143  \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total  +\vec{\mathbf{v}}_{h}\cdot \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$
1144  derivative, $f=2\Omega \sin lat$ is the Coriolis parameter, $\phi =gz$ is  is the total derivative, $f=2\Omega \sin \varphi$ is the Coriolis parameter,
1145  the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp  $\phi =gz$ is the geopotential, $\alpha =1/\rho $ is the specific volume,
1146  }{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref  $\omega =\frac{Dp }{Dt}$ is the vertical velocity in the $p-$coordinate.
1147  {eq:atmos-heat}) is the first law of thermodynamics where internal energy $  Equation(\ref {eq:atmos-heat}) is the first law of thermodynamics where internal
1148  e=c_{v}T$, $T$ is temperature, $Q$ is the rate of heating per unit mass and $  energy $e=c_{v}T$, $T$ is temperature, $Q$ is the rate of heating per unit mass
1149  p\frac{D\alpha }{Dt}$ is the work done by the fluid in compressing.  and $p\frac{D\alpha }{Dt}$ is the work done by the fluid in compressing.
1150    
1151  It is convenient to cast the heat equation in terms of potential temperature  It is convenient to cast the heat equation in terms of potential temperature
1152  $\theta $ so that it looks more like a generic conservation law.  $\theta $ so that it looks more like a generic conservation law.
# Line 1114  In $p$-coordinates, the upper boundary a Line 1207  In $p$-coordinates, the upper boundary a
1207  surface ($\phi $ is imposed and $\omega \neq 0$).  surface ($\phi $ is imposed and $\omega \neq 0$).
1208    
1209  \subsubsection{Splitting the geo-potential}  \subsubsection{Splitting the geo-potential}
1210    \label{sec:hpe-p-geo-potential-split}
1211    
1212  For the purposes of initialization and reducing round-off errors, the model  For the purposes of initialization and reducing round-off errors, the model
1213  deals with perturbations from reference (or ``standard'') profiles. For  deals with perturbations from reference (or ``standard'') profiles. For
# Line 1143  _{o}(p_{o})=g~Z_{topo}$, defined: Line 1237  _{o}(p_{o})=g~Z_{topo}$, defined:
1237  The final form of the HPE's in p coordinates is then:  The final form of the HPE's in p coordinates is then:
1238  \begin{eqnarray}  \begin{eqnarray}
1239  \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}}
1240  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}}
1241    \label{eq:atmos-prime} \\
1242  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\
1243  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1244  \partial p} &=&0 \\  \partial p} &=&0 \\
1245  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\
1246  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }  \label{eq:atmos-prime}  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }
1247  \end{eqnarray}  \end{eqnarray}
1248    
 % $Header$  
 % $Name$  
   
1249  \section{Appendix OCEAN}  \section{Appendix OCEAN}
1250    
1251  \subsection{Equations of motion for the ocean}  \subsection{Equations of motion for the ocean}
# Line 1167  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z} Line 1259  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}
1259  \epsilon _{nh}\frac{Dw}{Dt}+g+\frac{1}{\rho }\frac{\partial p}{\partial z}  \epsilon _{nh}\frac{Dw}{Dt}+g+\frac{1}{\rho }\frac{\partial p}{\partial z}
1260  &=&\epsilon _{nh}\mathcal{F}_{w} \\  &=&\epsilon _{nh}\mathcal{F}_{w} \\
1261  \frac{1}{\rho }\frac{D\rho }{Dt}+\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}  \frac{1}{\rho }\frac{D\rho }{Dt}+\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}
1262  _{h}+\frac{\partial w}{\partial z} &=&0 \\  _{h}+\frac{\partial w}{\partial z} &=&0 \label{eq-zns-cont}\\
1263  \rho &=&\rho (\theta ,S,p) \\  \rho &=&\rho (\theta ,S,p) \label{eq-zns-eos}\\
1264  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-zns-heat}\\
1265  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:non-boussinesq}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zns-salt}
1266    \label{eq:non-boussinesq}
1267  \end{eqnarray}  \end{eqnarray}
1268  These equations permit acoustics modes, inertia-gravity waves,  These equations permit acoustics modes, inertia-gravity waves,
1269  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermo-haline  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermohaline
1270  mode. As written, they cannot be integrated forward consistently - if we  mode. As written, they cannot be integrated forward consistently - if we
1271  step $\rho $ forward in (\ref{eq-zns-cont}), the answer will not be  step $\rho $ forward in (\ref{eq-zns-cont}), the answer will not be
1272  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref
# Line 1188  _{\theta ,p}\frac{DS}{Dt}+\left. \frac{\ Line 1281  _{\theta ,p}\frac{DS}{Dt}+\left. \frac{\
1281  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexpansion}  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexpansion}
1282  \end{equation}  \end{equation}
1283    
1284  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
1285  reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref  the reciprocal of the sound speed ($c_{s}$) squared. Substituting into
1286  {eq-zns-cont} gives:  \ref{eq-zns-cont} gives:
1287  \begin{equation}  \begin{equation}
1288  \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{
1289  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}
# Line 1367  the perturbation density. Nevertheless, Line 1460  the perturbation density. Nevertheless,
1460  _{nh}=0$ form of these equations that are used throughout the ocean modeling  _{nh}=0$ form of these equations that are used throughout the ocean modeling
1461  community and referred to as the primitive equations (HPE).  community and referred to as the primitive equations (HPE).
1462    
 % $Header$  
 % $Name$  
   
1463  \section{Appendix:OPERATORS}  \section{Appendix:OPERATORS}
1464    
1465  \subsection{Coordinate systems}  \subsection{Coordinate systems}
# Line 1380  In spherical coordinates, the velocity c Line 1470  In spherical coordinates, the velocity c
1470  and vertical direction respectively, are given by (see Fig.2) :  and vertical direction respectively, are given by (see Fig.2) :
1471    
1472  \begin{equation*}  \begin{equation*}
1473  u=r\cos \phi \frac{D\lambda }{Dt}  u=r\cos \varphi \frac{D\lambda }{Dt}
1474  \end{equation*}  \end{equation*}
1475    
1476  \begin{equation*}  \begin{equation*}
1477  v=r\frac{D\phi }{Dt}\qquad  v=r\frac{D\varphi }{Dt}
1478  \end{equation*}  \end{equation*}
 $\qquad \qquad \qquad \qquad $  
1479    
1480  \begin{equation*}  \begin{equation*}
1481  \dot{r}=\frac{Dr}{Dt}  \dot{r}=\frac{Dr}{Dt}
1482  \end{equation*}  \end{equation*}
1483    
1484  Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial  Here $\varphi $ is the latitude, $\lambda $ the longitude, $r$ the radial
1485  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
1486  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.
1487    
1488  The `grad' ($\nabla $) and `div' ($\nabla $.) operators are defined by, in  The `grad' ($\nabla $) and `div' ($\nabla\cdot$) operators are defined by, in
1489  spherical coordinates:  spherical coordinates:
1490    
1491  \begin{equation*}  \begin{equation*}
1492  \nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda }  \nabla \equiv \left( \frac{1}{r\cos \varphi }\frac{\partial }{\partial \lambda }
1493  ,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r}  ,\frac{1}{r}\frac{\partial }{\partial \varphi },\frac{\partial }{\partial r}
1494  \right)  \right)
1495  \end{equation*}  \end{equation*}
1496    
1497  \begin{equation*}  \begin{equation*}
1498  \nabla .v\equiv \frac{1}{r\cos \phi }\left\{ \frac{\partial u}{\partial  \nabla\cdot v\equiv \frac{1}{r\cos \varphi }\left\{ \frac{\partial u}{\partial
1499  \lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\}  \lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\}
1500  +\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}
1501  \end{equation*}  \end{equation*}
1502    

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