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3    
4  \pagebreak  %tci%\documentclass[12pt]{book}
5    %tci%\usepackage{amsmath}
6    %tci%\usepackage{html}
7    %tci%\usepackage{epsfig}
8    %tci%\usepackage{graphics,subfigure}
9    %tci%\usepackage{array}
10    %tci%\usepackage{multirow}
11    %tci%\usepackage{fancyhdr}
12    %tci%\usepackage{psfrag}
13    
14    %tci%%TCIDATA{OutputFilter=Latex.dll}
15    %tci%%TCIDATA{LastRevised=Thursday, October 04, 2001 14:41:22}
16    %tci%%TCIDATA{<META NAME="GraphicsSave" CONTENT="32">}
17    %tci%%TCIDATA{Language=American English}
18    
19    %tci%\fancyhead{}
20    %tci%\fancyhead[LO]{\slshape \rightmark}
21    %tci%\fancyhead[RE]{\slshape \leftmark}
22    %tci%\fancyhead[RO,LE]{\thepage}
23    %tci%\fancyfoot[CO,CE]{\today}
24    %tci%\fancyfoot[RO,LE]{ }
25    %tci%\renewcommand{\headrulewidth}{0.4pt}
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27    %tci%\setcounter{secnumdepth}{3}
28    %tci%\input{tcilatex}
29    
30  \part{MITgcm basics}  %tci%\begin{document}
31    
32  % Section: Overview  %tci%\tableofcontents
33    
 % $Header$  
 % $Name$  
34    
35  \section{Introduction}  % Section: Overview
36    
37  This documentation provides the reader with the information necessary to  This document 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 73  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.1%  models - see fig \ref{fig:onemodel}
59  \marginpar{  
60  Fig.1 One model}\ref{fig:onemodel}  %% CNHbegin
61    \input{s_overview/text/one_model_figure}
62  \begin{figure}  %% CNHend
 \begin{center}  
 \resizebox{!}{4in}{  
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/onemodel.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:onemodel}  
 \end{figure}  
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.2%  small-scale and large scale processes - see fig \ref{fig:all-scales}
 \marginpar{  
 Fig.2 All scales}\ref{fig:all-scales}  
   
   
 \begin{figure}  
 \begin{center}  
 \resizebox{!}{4in}{  
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/scales.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:scales}  
 \end{figure}  
66    
67    %% CNHbegin
68    \input{s_overview/text/all_scales_figure}
69    %% 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.3%  orthogonal curvilinear grids and shaved cells - see fig \ref{fig:finite-volumes}
74  \marginpar{  
75  Fig.3 Finite volumes}\ref{fig:Finite volumes}  %% CNHbegin
76    \input{s_overview/text/fvol_figure}
77    %% CNHend
78    
79  \item tangent linear and adjoint counterparts are automatically maintained  \item tangent linear and adjoint counterparts are automatically maintained
80  along with the forward model, permitting sensitivity and optimization  along with the forward model, permitting sensitivity and optimization
# Line 129  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 it is easy to reproduce the results shown here: simply  given later. Indeed many of the illustrative examples shown below can be
148  download the model (the minimum you need is a PC running linux, together  easily reproduced: simply download the model (the minimum you need is a PC
149  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.
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    
 Fig.E1a.\ref{fig:Held-Suarez} is an instaneous plot of the 500$mb$ height  
 field obtained using a 5-level version of the atmospheric pressure isomorph  
 run at 2.8$^{\circ }$ resolution. We see fully developed baroclinic eddies  
 along the northern hemisphere storm track. There are no mountains or  
 land-sea contrast in this calculation, but you can easily put them in. The  
 model is driven by relaxation to a radiative-convective equilibrium profile,  
 following the description set out in Held and Suarez; 1994 designed to test  
 atmospheric hydrodynamical cores - there are no mountains or land-sea  
 contrast. As decribed in Adcroft (2001), a `cubed sphere' is used to  
 descretize the globe permitting a uniform gridding and obviated the need to  
 fourier filter.  
   
 Fig.E1b shows the 5-year mean, zonally averaged potential temperature, zonal  
 wind and meridional overturning streamfunction from the 5-level model.  
   
   
 \begin{figure}  
 \begin{center}  
 \resizebox{!}{4in}{  
  \rotatebox{90}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/hscs.eps}  
  }  
 }  
 \end{center}  
 \label{fig:hscs}  
 \end{figure}  
   
   
 A regular spherical lat-lon grid can also be used.  
   
 \begin{figure}  
 \begin{center}  
 \resizebox{!}{4in}{  
  \rotatebox{90}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/hslatlon.eps}  
  }  
 }  
 \end{center}  
 \label{fig:hslatlon}  
 \end{figure}  
157    
 \subsection{Ocean gyres}  
158    
159  \subsection{Global ocean circulation}  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
164    $2.8^{\circ }$ resolution on the cubed sphere. We see cold air over the pole
165    (blue) and warm air along an equatorial band (red). Fully developed
166    baroclinic eddies spawned in the northern hemisphere storm track are
167    evident. There are no mountains or land-sea contrast in this calculation,
168    but you can easily put them in. The model is driven by relaxation to a
169    radiative-convective equilibrium profile, following the description set out
170    in Held and Suarez; 1994 designed to test atmospheric hydrodynamical cores -
171    there are no mountains or land-sea contrast.
172    
173    %% CNHbegin
174    \input{s_overview/text/cubic_eddies_figure}
175    %% CNHend
176    
177    As described in Adcroft (2001), a `cubed sphere' is used to discretize the
178    globe permitting a uniform griding and obviated the need to Fourier filter.
179    The `vector-invariant' form of MITgcm supports any orthogonal curvilinear
180    grid, of which the cubed sphere is just one of many choices.
181    
182    Figure \ref{fig:hs_zave_u} shows the 5-year mean, zonally averaged zonal
183    wind from a 20-level configuration of
184    the model. It compares favorable with more conventional spatial
185    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    latitude-longitude grid. Both grids are supported within the model.
188    
189    %% CNHbegin
190    \input{s_overview/text/hs_zave_u_figure}
191    %% CNHend
192    
193  Fig.E2a shows the pattern of ocean currents at the surface of a 4$^{\circ }$  \subsection{Ocean gyres}
194  global ocean model run with 15 vertical levels. The model is driven using  \begin{rawhtml}
195  monthly-mean winds with mixed boundary conditions on temperature and  <!-- CMIREDIR:oceanic_example: -->
196  salinity at the surface. Fig.E2b shows the overturning (thermohaline)  \end{rawhtml}
197  circulation. Lopped cells are used to represent topography on a regular $%  \begin{rawhtml}
198  lat-lon$ grid extending from 70$^{\circ }N$ to 70$^{\circ }S$.  <!-- CMIREDIR:ocean_gyres: -->
199    \end{rawhtml}
200    
201  \begin{figure}  Baroclinic instability is a ubiquitous process in the ocean, as well as the
202  \begin{center}  atmosphere. Ocean eddies play an important role in modifying the
203  \resizebox{!}{4in}{  hydrographic structure and current systems of the oceans. Coarse resolution
204  % \rotatebox{90}{  models of the oceans cannot resolve the eddy field and yield rather broad,
205    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/ocean_circ_455_2030.eps}  diffusive patterns of ocean currents. But if the resolution of our models is
206  % }  increased until the baroclinic instability process is resolved, numerical
207  }  solutions of a different and much more realistic kind, can be obtained.
208  \end{center}  
209  \label{fig:horizcirc}  Figure \ref{fig:ocean-gyres} shows the surface temperature and
210  \end{figure}  velocity field obtained from MITgcm run at $\frac{1}{6}^{\circ }$
211    horizontal resolution on a \textit{lat-lon} grid in which the pole has
212  \begin{figure}  been rotated by $90^{\circ }$ on to the equator (to avoid the
213  \begin{center}  converging of meridian in northern latitudes). 21 vertical levels are
214  \resizebox{!}{4in}{  used in the vertical with a `lopped cell' representation of
215   \rotatebox{90}{  topography. The development and propagation of anomalously warm and
216   \rotatebox{180}{  cold eddies can be clearly seen in the Gulf Stream region. The
217    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/moc.eps}  transport of warm water northward by the mean flow of the Gulf Stream
218   }  is also clearly visible.
219   }  
220  }  %% CNHbegin
221  \end{center}  \input{s_overview/text/atl6_figure}
222  \label{fig:moc}  %% CNHend
 \end{figure}  
   
   
 \subsection{Flow over topography}  
   
 \subsection{Ocean convection}  
   
 Fig.E3 shows convection over a slope using the non-hydrostatic ocean  
 isomorph and lopped cells to respresent topography. .....The grid resolution  
 is  
   
 \subsection{Boundary forced internal waves}  
   
 \subsection{Carbon outgassing sensitivity}  
   
 Fig.E4 shows....  
223    
 \begin{figure}  
 \begin{center}  
 \resizebox{!}{4in}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/co209.eps}  
 }  
 \end{center}  
 \label{fig:co2mrt}  
 \end{figure}  
224    
225    \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    Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning
240    circulation of the global ocean in Sverdrups.
241    
242    %%CNHbegin
243    \input{s_overview/text/global_circ_figure}
244    %%CNHend
245    
246    \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
253    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
255    mechanism for moving dense fluid down the shelf is then through geostrophic
256    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
259    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
261    entrainment in the vertical plane is reduced when rotational control is
262    strong, and replaced by lateral entrainment due to the baroclinic
263    instability of the along-slope current.
264    
265    %%CNHbegin
266    \input{s_overview/text/convect_and_topo}
267    %%CNHend
268    
269  % $Header$  \subsection{Boundary forced internal waves}
270  % $Name$  \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
275    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
277    barotropic tidal currents imposed through open boundary conditions.
278    
279    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
282    contoured. The internal waves are excited by application of open boundary
283    conditions on the left. They propagate to the sloping boundary (represented
284    using MITgcm's finite volume spatial discretization) where they break under
285    nonhydrostatic dynamics.
286    
287    %%CNHbegin
288    \input{s_overview/text/boundary_forced_waves}
289    %%CNHend
290    
291    \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
297    `automatic adjoint compiler'. These can be used in parameter sensitivity and
298    data assimilation studies.
299    
300    As one example of application of the MITgcm adjoint, Figure
301    \ref{fig:hf-sensitivity} maps the gradient $\frac{\partial J}{\partial
302      \mathcal{H}}$where $J$ is the magnitude of the overturning
303    stream-function shown in figure \ref{fig:large-scale-circ} at
304    $60^{\circ }N$ and $ \mathcal{H}(\lambda,\varphi)$ is the mean, local
305    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.
309    
310    %%CNHbegin
311    \input{s_overview/text/adj_hf_ocean_figure}
312    %%CNHend
313    
314    \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
321    ocean circulation. An appropriately defined `cost function', which measures
322    the departure of the model from observations (both remotely sensed and
323    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
325    etc. Figure \ref{fig:assimilated-globes} shows the large scale planetary
326    circulation and a Hopf-Muller plot of Equatorial sea-surface height.
327    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
332    \input{s_overview/text/assim_figure}
333    %% CNHend
334    
335    \subsection{Ocean biogeochemical cycles}
336    \begin{rawhtml}
337    <!-- CMIREDIR:ocean_biogeo_cycles: -->
338    \end{rawhtml}
339    
340    MITgcm is being used to study global biogeochemical cycles in the
341    ocean. For example one can study the effects of interannual changes in
342    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
352    \input{s_overview/text/biogeo_figure}
353    %%CNHend
354    
355    \subsection{Simulations of laboratory experiments}
356    \begin{rawhtml}
357    <!-- CMIREDIR:classroom_exp: -->
358    \end{rawhtml}
359    
360    Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a
361    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
363    free surface by a rotating heated disk. The combined action of mechanical
364    and thermal forcing creates a lens of fluid which becomes baroclinically
365    unstable. The stratification and depth of penetration of the lens is
366    arrested by its instability in a process analogous to that which sets the
367    stratification of the ACC.
368    
369    %%CNHbegin
370    \input{s_overview/text/lab_figure}
371    %%CNHend
372    
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
390    \input{s_overview/text/zandpcoord_figure.tex}
391    %%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
394  velocity $\vec{\mathbf{v}}$, active tracers $\theta $ and $S$, a  velocity $\vec{\mathbf{v}}$, active tracers $\theta $ and $S$, a
# Line 276  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}.
   
 \begin{figure}  
 \begin{center}  
 \resizebox{!}{4in}{  
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/vertcoord.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:vertcoord}  
 \end{figure}  
   
 \begin{equation*}  
 \frac{D\vec{\mathbf{v}_{h}}}{Dt}+\left( 2\vec{\Omega}\times \vec{\mathbf{v}}%  
 \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}%  
 \text{ horizontal mtm}  
 \end{equation*}  
402    
403  \begin{equation*}  %%CNHbegin
404  \frac{D\dot{r}}{Dt}+\widehat{k}\cdot \left( 2\vec{\Omega}\times \vec{\mathbf{%  \input{s_overview/text/vertcoord_figure.tex}
405    %%CNHend
406    
407    \begin{equation}
408    \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}}}
410    \text{ horizontal mtm} \label{eq:horizontal_mtm}
411    \end{equation}
412    
413    \begin{equation}
414    \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    
440  \begin{equation*}  \begin{equation*}
441  r\text{ is the vertical coordinate}  r\text{ is the vertical coordinate}
442  \end{equation*}  \end{equation*}
443    
444  \begin{equation*}  \begin{equation*}
445  \frac{D}{Dt}=\frac{\partial }{\partial t}+\vec{\mathbf{v}}\cdot \nabla \text{  \frac{D}{Dt}=\frac{\partial }{\partial t}+\vec{\mathbf{v}}\cdot \nabla \text{
446  is the total derivative}  is the total derivative}
447  \end{equation*}  \end{equation*}
448    
449  \begin{equation*}  \begin{equation*}
450  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}%  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}
451  \text{ is the `grad' operator}  \text{ is the `grad' operator}
452  \end{equation*}  \end{equation*}
453  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}%  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}
454  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$
455  is a unit vector in the vertical  is a unit vector in the vertical
456    
457  \begin{equation*}  \begin{equation*}
458  t\text{ is time}  t\text{ is time}
459  \end{equation*}  \end{equation*}
460    
461  \begin{equation*}  \begin{equation*}
462  \vec{\mathbf{v}}=(u,v,\dot{r})=(\vec{\mathbf{v}}_{h},\dot{r})\text{ is the  \vec{\mathbf{v}}=(u,v,\dot{r})=(\vec{\mathbf{v}}_{h},\dot{r})\text{ is the
463  velocity}  velocity}
464  \end{equation*}  \end{equation*}
465    
466  \begin{equation*}  \begin{equation*}
467  \phi \text{ is the `pressure'/`geopotential'}  \phi \text{ is the `pressure'/`geopotential'}
468  \end{equation*}  \end{equation*}
469    
470  \begin{equation*}  \begin{equation*}
471  \vec{\Omega}\text{ is the Earth's rotation}  \vec{\Omega}\text{ is the Earth's rotation}
472  \end{equation*}  \end{equation*}
473    
474  \begin{equation*}  \begin{equation*}
475  b\text{ is the `buoyancy'}  b\text{ is the `buoyancy'}
476  \end{equation*}  \end{equation*}
477    
478  \begin{equation*}  \begin{equation*}
479  \theta \text{ is potential temperature}  \theta \text{ is potential temperature}
480  \end{equation*}  \end{equation*}
481    
482  \begin{equation*}  \begin{equation*}
483  S\text{ is specific humidity in the atmosphere; salinity in the ocean}  S\text{ is specific humidity in the atmosphere; salinity in the ocean}
484  \end{equation*}  \end{equation*}
485    
486  \begin{equation*}  \begin{equation*}
487  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{%  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{
488  \mathbf{v}}  \mathbf{v}}
489  \end{equation*}  \end{equation*}
490    
491  \begin{equation*}  \begin{equation*}
492  \mathcal{Q}_{\theta }\mathcal{\ }\text{are forcing and dissipation of }%  \mathcal{Q}_{\theta }\mathcal{\ }\text{are forcing and dissipation of }\theta
 \theta  
493  \end{equation*}  \end{equation*}
494    
495  \begin{equation*}  \begin{equation*}
# Line 385  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
520    
521  \begin{equation*}  \begin{equation*}
522  R_{moving}=R_{o}+\eta  R_{moving}=R_{o}+\eta
523  \end{equation*}  \end{equation*}
524  where $R_{o}(x,y)$ is the `$r-$value' (height or pressure, depending on  where $R_{o}(x,y)$ is the `$r-$value' (height or pressure, depending on
525  whether we are in the atmosphere or ocean) of the `moving surface' in the  whether we are in the atmosphere or ocean) of the `moving surface' in the
# Line 417  of motion. Line 530  of motion.
530    
531  \begin{equation}  \begin{equation}
532  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}
533  \end{equation}%  \end{equation}
534  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.
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 454  where Line 567  where
567    
568  \begin{equation*}  \begin{equation*}
569  T\text{ is absolute temperature}  T\text{ is absolute temperature}
570  \end{equation*}%  \end{equation*}
571  \begin{equation*}  \begin{equation*}
572  p\text{ is the pressure}  p\text{ is the pressure}
573  \end{equation*}%  \end{equation*}
574  \begin{eqnarray*}  \begin{eqnarray*}
575  &&z\text{ is the height of the pressure surface} \\  &&z\text{ is the height of the pressure surface} \\
576  &&g\text{ is the acceleration due to gravity}  &&g\text{ is the acceleration due to gravity}
# Line 467  In the above the ideal gas law, $p=\rho Line 580  In the above the ideal gas law, $p=\rho
580  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)
581  \begin{equation}  \begin{equation}
582  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}
583  \end{equation}%  \end{equation}
584  where $p_{c}$ is a reference pressure and $\kappa =R/c_{p}$ with $R$ the gas  where $p_{c}$ is a reference pressure and $\kappa =R/c_{p}$ with $R$ the gas
585  constant and $c_{p}$ the specific heat of air at constant pressure.  constant and $c_{p}$ the specific heat of air at constant pressure.
586    
587  At the top of the atmosphere (which is `fixed' in our $r$ coordinate):  At the top of the atmosphere (which is `fixed' in our $r$ coordinate):
588    
589  \begin{equation*}  \begin{equation*}
590  R_{fixed}=p_{top}=0  R_{fixed}=p_{top}=0
591  \end{equation*}  \end{equation*}
592  In a resting atmosphere the elevation of the mountains at the bottom is  In a resting atmosphere the elevation of the mountains at the bottom is
593  given by  given by
594  \begin{equation*}  \begin{equation*}
595  R_{moving}=R_{o}(x,y)=p_{o}(x,y)  R_{moving}=R_{o}(x,y)=p_{o}(x,y)
596  \end{equation*}  \end{equation*}
597  i.e. the (hydrostatic) pressure at the top of the mountains in a resting  i.e. the (hydrostatic) pressure at the top of the mountains in a resting
598  atmosphere.  atmosphere.
# Line 493  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 517  At the bottom of the ocean: $R_{fixed}(x Line 632  At the bottom of the ocean: $R_{fixed}(x
632    
633  The surface of the ocean is given by: $R_{moving}=\eta $  The surface of the ocean is given by: $R_{moving}=\eta $
634    
635  The position of the resting free surface of the ocean is given by $%  The position of the resting free surface of the ocean is given by $
636  R_{o}=Z_{o}=0$.  R_{o}=Z_{o}=0$.
637    
638  Boundary conditions are:  Boundary conditions are:
# Line 525  Boundary conditions are: Line 640  Boundary conditions are:
640  \begin{eqnarray}  \begin{eqnarray}
641  w &=&0~\text{at }r=R_{fixed}\text{ (ocean bottom)}  \label{eq:fixed-bc-ocean}  w &=&0~\text{at }r=R_{fixed}\text{ (ocean bottom)}  \label{eq:fixed-bc-ocean}
642  \\  \\
643  w &=&\frac{D\eta }{Dt}\text{ at }r=R_{moving}=\eta \text{ (ocean surface) %  w &=&\frac{D\eta }{Dt}\text{ at }r=R_{moving}=\eta \text{ (ocean surface)
644  \label{eq:moving-bc-ocean}}  \label{eq:moving-bc-ocean}}
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    
663  \begin{equation}  \begin{equation}
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 556  _{nh}=\vec{\mathbf{G}}_{\vec{v}_{h}}  \l Line 679  _{nh}=\vec{\mathbf{G}}_{\vec{v}_{h}}  \l
679  \end{equation}  \end{equation}
680    
681  \begin{equation}  \begin{equation}
682  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{%  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{
683  \partial r}=G_{\dot{r}}  \label{eq:mom-w}  \partial r}=G_{\dot{r}}  \label{eq:mom-w}
684  \end{equation}  \end{equation}
685  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.
686    
687  The $\left( \vec{\mathbf{G}}_{\vec{v}},G_{\dot{r}}\right) $ in eq(\ref%  The $\left( \vec{\mathbf{G}}_{\vec{v}},G_{\dot{r}}\right) $ in eq(\ref
688  {eq:mom-h}) and (\ref{eq:mom-w}) represent advective, metric and Coriolis  {eq:mom-h}) and (\ref{eq:mom-w}) represent advective, metric and Coriolis
689  terms in the momentum equations. In spherical coordinates they take the form%  terms in the momentum equations. In spherical coordinates they take the form
690  \footnote{%  \footnote{
691  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms
692  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref%  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref
693  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in
694  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (%  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (
695  \textbf{NH}) includes all terms.} - see Marshall et al 1997a for a full  \textbf{NH}) includes all terms.} - see Marshall et al 1997a for a full
696  discussion:  discussion:
697    
# Line 576  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}
708  \ \right\} \left\{  \ \right\} \left\{
709  \begin{tabular}{l}  \begin{tabular}{l}
710  \textit{advection} \\  \textit{advection} \\
711  \textit{metric} \\  \textit{metric} \\
712  \textit{Coriolis} \\  \textit{Coriolis} \\
713  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
714  \end{tabular}%  \end{tabular}
715  \ \right. \qquad   \label{eq:gu-speherical}  \ \right. \qquad  \label{eq:gu-speherical}
716  \end{equation}  \end{equation}
717    
718  \begin{equation}  \begin{equation}
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\{
728  \begin{tabular}{l}  \begin{tabular}{l}
729  \textit{advection} \\  \textit{advection} \\
730  \textit{metric} \\  \textit{metric} \\
731  \textit{Coriolis} \\  \textit{Coriolis} \\
732  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
733  \end{tabular}%  \end{tabular}
734  \ \right. \qquad   \label{eq:gv-spherical}  \ \right. \qquad  \label{eq:gv-spherical}
735  \end{equation}%  \end{equation}
736  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
737    
738  \begin{equation}  \begin{equation}
739  \left.  \left.
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\{
747  \begin{tabular}{l}  \begin{tabular}{l}
748  \textit{advection} \\  \textit{advection} \\
749  \textit{metric} \\  \textit{metric} \\
750  \textit{Coriolis} \\  \textit{Coriolis} \\
751  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
752  \end{tabular}%  \end{tabular}
753  \ \right.   \label{eq:gw-spherical}  \ \right.  \label{eq:gw-spherical}
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.}  
   
 \begin{figure}  
 \begin{center}  
 \resizebox{!}{4in}{  
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/spherical-polar.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:spcoord}  
 \end{figure}  
762    
763    %%CNHbegin
764    \input{s_overview/text/sphere_coord_figure.tex}
765    %%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 $r  non-hydrostatic forms the shallow atmosphere approximation can be
776  $ 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 674  terms in Eqs. (\ref{eq:gu-speherical} $\ Line 787  terms in Eqs. (\ref{eq:gu-speherical} $\
787  are neglected and `${r}$' is replaced by `$a$', the mean radius of the  are neglected and `${r}$' is replaced by `$a$', the mean radius of the
788  earth. Once the pressure is found at one level - e.g. by inverting a 2-d  earth. Once the pressure is found at one level - e.g. by inverting a 2-d
789  Elliptic equation for $\phi _{s}$ at $r=R_{moving}$ - the pressure can be  Elliptic equation for $\phi _{s}$ at $r=R_{moving}$ - the pressure can be
790  computed at all other levels by integration of the hydrostatic relation, eq(%  computed at all other levels by integration of the hydrostatic relation, eq(
791  \ref{eq:hydrostatic}).  \ref{eq:hydrostatic}).
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
799  \textbf{QH}\ \textit{all} the metric terms are retained and the full  \textbf{QH}\ \textit{all} the metric terms are retained and the full
# Line 688  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 699  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}
819    
820  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref%  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref
821  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A
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 717  and Bromley, 1995; Marshall et.al.\ 1997 Line 830  and Bromley, 1995; Marshall et.al.\ 1997
830    
831  \paragraph{Quasi-nonhydrostatic Atmosphere}  \paragraph{Quasi-nonhydrostatic Atmosphere}
832    
833  In the non-hydrostatic version of our atmospheric model we approximate $\dot{%  In the non-hydrostatic version of our atmospheric model we approximate $\dot{
834  r}$ in the vertical momentum eqs(\ref{eq:mom-w}) and (\ref{eq:gv-spherical})  r}$ in the vertical momentum eqs(\ref{eq:mom-w}) and (\ref{eq:gv-spherical})
835  (but only here) by:  (but only here) by:
836    
837  \begin{equation}  \begin{equation}
838  \dot{r}=\frac{Dp}{Dt}=\frac{1}{g}\frac{D\phi }{Dt}  \label{eq:quasi-nh-w}  \dot{r}=\frac{Dp}{Dt}=\frac{1}{g}\frac{D\phi }{Dt}  \label{eq:quasi-nh-w}
839  \end{equation}%  \end{equation}
840  where $p_{hy}$ is the hydrostatic pressure.  where $p_{hy}$ is the hydrostatic pressure.
841    
842  \subsubsection{Summary of equation sets supported by model}  \subsubsection{Summary of equation sets supported by model}
# Line 751  equations in $z-$coordinates are support Line 864  equations in $z-$coordinates are support
864    
865  \subparagraph{Non-hydrostatic}  \subparagraph{Non-hydrostatic}
866    
867  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$%  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$
868  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref%  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref
869  {eq:ocean-salt}).  {eq:ocean-salt}).
870    
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 769  forward and $\dot{r}$ found from continu Line 881  forward and $\dot{r}$ found from continu
881  stepping forward the horizontal momentum equations; $\dot{r}$ is found by  stepping forward the horizontal momentum equations; $\dot{r}$ is found by
882  stepping forward the vertical momentum equation.  stepping forward the vertical momentum equation.
883    
884  \begin{figure}  %%CNHbegin
885  \begin{center}  \input{s_overview/text/solution_strategy_figure.tex}
886  \resizebox{!}{4in}{  %%CNHend
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/soln_strategy.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:solnstart}  
 \end{figure}  
   
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 794  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 808  Hydrostatic pressure is obtained by inte Line 911  Hydrostatic pressure is obtained by inte
911  vertically from $r=R_{o}$ where $\phi _{hyd}(r=R_{o})=0$, to yield:  vertically from $r=R_{o}$ where $\phi _{hyd}(r=R_{o})=0$, to yield:
912    
913  \begin{equation*}  \begin{equation*}
914  \int_{r}^{R_{o}}\frac{\partial \phi _{hyd}}{\partial r}dr=\left[ \phi _{hyd}%  \int_{r}^{R_{o}}\frac{\partial \phi _{hyd}}{\partial r}dr=\left[ \phi _{hyd}
915  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr
916  \end{equation*}  \end{equation*}
917  and so  and so
918    
# Line 826  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}
937  }_{h}+\partial _{r}\dot{r}\right) dr=0  }_{h}+\partial _{r}\dot{r}\right) dr=0
938  \end{equation*}  \end{equation*}
939    
940  Thus:  Thus:
941    
942  \begin{equation*}  \begin{equation*}
943  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta
944  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}%  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}
945  _{h}dr=0  _{h}dr=0
946  \end{equation*}  \end{equation*}
947  where $\eta =R_{moving}-R_{o}$ is the free-surface $r$-anomaly in units of $%  where $\eta =R_{moving}-R_{o}$ is the free-surface $r$-anomaly in units of $
948  r $. The above can be rearranged to yield, using Leibnitz's theorem:  r $. The above can be rearranged to yield, using Leibnitz's theorem:
949    
950  \begin{equation}  \begin{equation}
951  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot
952  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}
953  \label{eq:free-surface}  \label{eq:free-surface}
954  \end{equation}%  \end{equation}
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)
962  \label{eq:phi-surf}  \label{eq:phi-surf}
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{
979  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .%  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .
980  \vec{\mathbf{F}}  \label{eq:3d-invert}  \vec{\mathbf{F}}  \label{eq:3d-invert}
981  \end{equation}  \end{equation}
982    
# Line 893  coasts (in the ocean) and the bottom: Line 996  coasts (in the ocean) and the bottom:
996  \end{equation}  \end{equation}
997  where $\widehat{n}$ is a vector of unit length normal to the boundary. The  where $\widehat{n}$ is a vector of unit length normal to the boundary. The
998  kinematic condition (\ref{nonormalflow}) is also applied to the vertical  kinematic condition (\ref{nonormalflow}) is also applied to the vertical
999  velocity at $r=R_{moving}$. No-slip $\left( v_{T}=0\right) \ $or slip $%  velocity at $r=R_{moving}$. No-slip $\left( v_{T}=0\right) \ $or slip $
1000  \left( \partial v_{T}/\partial n=0\right) \ $conditions are employed on the  \left( \partial v_{T}/\partial n=0\right) \ $conditions are employed on the
1001  tangential component of velocity, $v_{T}$, at all solid boundaries,  tangential component of velocity, $v_{T}$, at all solid boundaries,
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 910  where Line 1013  where
1013  \begin{equation*}  \begin{equation*}
1014  \vec{\mathbf{F}}=\vec{\mathbf{G}}_{\vec{v}}-\left( \mathbf{\nabla }_{h}\phi  \vec{\mathbf{F}}=\vec{\mathbf{G}}_{\vec{v}}-\left( \mathbf{\nabla }_{h}\phi
1015  _{s}+\mathbf{\nabla }\phi _{hyd}\right)  _{s}+\mathbf{\nabla }\phi _{hyd}\right)
1016  \end{equation*}%  \end{equation*}
1017  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem
1018  (\ref{eq:3d-invert}). As shown, for example, by Williams (1969), one can  (\ref{eq:3d-invert}). As shown, for example, by Williams (1969), one can
1019  exploit classical 3D potential theory and, by introducing an appropriately  exploit classical 3D potential theory and, by introducing an appropriately
1020  chosen $\delta $-function sheet of `source-charge', replace the inhomogenous  chosen $\delta $-function sheet of `source-charge', replace the
1021  boundary condition on pressure by a homogeneous one. The source term $rhs$  inhomogeneous boundary condition on pressure by a homogeneous one. The
1022  in (\ref{eq:3d-invert}) is the divergence of the vector $\vec{\mathbf{F}}.$  source term $rhs$ in (\ref{eq:3d-invert}) is the divergence of the vector $
1023  By simultaneously setting $%  \vec{\mathbf{F}}.$ By simultaneously setting $
1024  \begin{array}{l}  \begin{array}{l}
1025  \widehat{n}.\vec{\mathbf{F}}%  \widehat{n}.\vec{\mathbf{F}}
1026  \end{array}%  \end{array}
1027  =0$\ and $\widehat{n}.\nabla \phi _{nh}=0\ $on the boundary the following  =0$\ and $\widehat{n}.\nabla \phi _{nh}=0\ $on the boundary the following
1028  self-consistent but simpler homogenised Elliptic problem is obtained:  self-consistent but simpler homogenized Elliptic problem is obtained:
1029    
1030  \begin{equation*}  \begin{equation*}
1031  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad
1032  \end{equation*}%  \end{equation*}
1033  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such
1034  that $\widetilde{\vec{\mathbf{F}}}.\widehat{n}=0$. As is implied by (\ref%  that $\widetilde{\vec{\mathbf{F}}}.\widehat{n}=0$. As is implied by (\ref
1035  {eq:inhom-neumann-nh}) the modified boundary condition becomes:  {eq:inhom-neumann-nh}) the modified boundary condition becomes:
1036    
1037  \begin{equation}  \begin{equation}
# Line 939  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 947  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 957  Many forms of momentum dissipation are a Line 1060  Many forms of momentum dissipation are a
1060  biharmonic frictions are commonly used:  biharmonic frictions are commonly used:
1061    
1062  \begin{equation}  \begin{equation}
1063  D_{V}=A_{h}\nabla _{h}^{2}v+A_{v}\frac{\partial ^{2}v}{\partial z^{2}}%  D_{V}=A_{h}\nabla _{h}^{2}v+A_{v}\frac{\partial ^{2}v}{\partial z^{2}}
1064  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}
1065  \end{equation}  \end{equation}
1066  where $A_{h}$ and $A_{v}\ $are (constant) horizontal and vertical viscosity  where $A_{h}$ and $A_{v}\ $are (constant) horizontal and vertical viscosity
# Line 968  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}
1078  \end{equation}  \end{equation}
1079  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $%  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $
1080  horizontal coefficient for biharmonic diffusion. In the simplest case where  horizontal coefficient for biharmonic diffusion. In the simplest case where
1081  the subgrid-scale fluxes of heat and salt are parameterized with constant  the subgrid-scale fluxes of heat and salt are parameterized with constant
1082  horizontal and vertical diffusion coefficients, $\underline{\underline{K}}$,  horizontal and vertical diffusion coefficients, $\underline{\underline{K}}$,
# Line 984  reduces to a diagonal matrix with consta Line 1087  reduces to a diagonal matrix with consta
1087  \begin{array}{ccc}  \begin{array}{ccc}
1088  K_{h} & 0 & 0 \\  K_{h} & 0 & 0 \\
1089  0 & K_{h} & 0 \\  0 & K_{h} & 0 \\
1090  0 & 0 & K_{v}%  0 & 0 & K_{v}
1091  \end{array}  \end{array}
1092  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}
1093  \end{equation}  \end{equation}
# Line 994  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}
1106  +\left( \nabla \times \vec{\mathbf{v}}\right) \times \vec{\mathbf{v}}+\nabla %  +\left( \nabla \times \vec{\mathbf{v}}\right) \times \vec{\mathbf{v}}+\nabla
1107  \left[ \frac{1}{2}(\vec{\mathbf{v}}\cdot \vec{\mathbf{v}})\right]  \left[ \frac{1}{2}(\vec{\mathbf{v}}\cdot \vec{\mathbf{v}})\right]
1108  \label{eq:vi-identity}  \label{eq:vi-identity}
1109  \end{equation}%  \end{equation}
1110  This permits alternative numerical treatments of the non-linear terms based  This permits alternative numerical treatments of the non-linear terms based
1111  on their representation as a vorticity flux. Because gradients of coordinate  on their representation as a vorticity flux. Because gradients of coordinate
1112  vectors no longer appear on the rhs of (\ref{eq:vi-identity}), explicit  vectors no longer appear on the rhs of (\ref{eq:vi-identity}), explicit
1113  representation of the metric terms in (\ref{eq:gu-speherical}), (\ref%  representation of the metric terms in (\ref{eq:gu-speherical}), (\ref
1114  {eq:gv-spherical}) and (\ref{eq:gw-spherical}), can be avoided: information  {eq:gv-spherical}) and (\ref{eq:gw-spherical}), can be avoided: information
1115  about the geometry is contained in the areas and lengths of the volumes used  about the geometry is contained in the areas and lengths of the volumes used
1116  to discretize the model.  to discretize the model.
1117    
1118  \subsection{Adjoint}  \subsection{Adjoint}
1119    
1120  Tangent linear and adoint counterparts of the forward model and described in  Tangent linear and adjoint counterparts of the forward model are described
1121  Chapter 5.  in Chapter 5.
   
 % $Header$  
 % $Name$  
1122    
1123  \section{Appendix ATMOSPHERE}  \section{Appendix ATMOSPHERE}
1124    
# Line 1028  coordinates} Line 1129  coordinates}
1129    
1130  The hydrostatic primitive equations (HPEs) in p-coordinates are:  The hydrostatic primitive equations (HPEs) in p-coordinates are:
1131  \begin{eqnarray}  \begin{eqnarray}
1132  \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}}
1133  _{h}+\mathbf{\nabla }_{p}\phi  &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\mathbf{\nabla }_{p}\phi &=&\vec{\mathbf{\mathcal{F}}}
1134  \label{eq:atmos-mom} \\  \label{eq:atmos-mom} \\
1135  \frac{\partial \phi }{\partial p}+\alpha  &=&0  \label{eq-p-hydro-start} \\  \frac{\partial \phi }{\partial p}+\alpha &=&0  \label{eq-p-hydro-start} \\
1136  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{%  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1137  \partial p} &=&0  \label{eq:atmos-cont} \\  \partial p} &=&0  \label{eq:atmos-cont} \\
1138  p\alpha  &=&RT  \label{eq:atmos-eos} \\  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.
1153  Differentiating (\ref{eq:atmos-eos}) we get:  Differentiating (\ref{eq:atmos-eos}) we get:
1154  \begin{equation*}  \begin{equation*}
1155  p\frac{D\alpha }{Dt}+\alpha \frac{Dp}{Dt}=R\frac{DT}{Dt}  p\frac{D\alpha }{Dt}+\alpha \frac{Dp}{Dt}=R\frac{DT}{Dt}
1156  \end{equation*}%  \end{equation*}
1157  which, when added to the heat equation (\ref{eq:atmos-heat}) and using $%  which, when added to the heat equation (\ref{eq:atmos-heat}) and using $
1158  c_{p}=c_{v}+R$, gives:  c_{p}=c_{v}+R$, gives:
1159  \begin{equation}  \begin{equation}
1160  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}
1161  \label{eq-p-heat-interim}  \label{eq-p-heat-interim}
1162  \end{equation}%  \end{equation}
1163  Potential temperature is defined:  Potential temperature is defined:
1164  \begin{equation}  \begin{equation}
1165  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}
1166  \end{equation}%  \end{equation}
1167  where $p_{c}$ is a reference pressure and $\kappa =R/c_{p}$. For convenience  where $p_{c}$ is a reference pressure and $\kappa =R/c_{p}$. For convenience
1168  we will make use of the Exner function $\Pi (p)$ which defined by:  we will make use of the Exner function $\Pi (p)$ which defined by:
1169  \begin{equation}  \begin{equation}
1170  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}
1171  \end{equation}%  \end{equation}
1172  The following relations will be useful and are easily expressed in terms of  The following relations will be useful and are easily expressed in terms of
1173  the Exner function:  the Exner function:
1174  \begin{equation*}  \begin{equation*}
1175  c_{p}T=\Pi \theta \;\;;\;\;\frac{\partial \Pi }{\partial p}=\frac{\kappa \Pi  c_{p}T=\Pi \theta \;\;;\;\;\frac{\partial \Pi }{\partial p}=\frac{\kappa \Pi
1176  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{%  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{
1177  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}%  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}
1178  \frac{Dp}{Dt}  \frac{Dp}{Dt}
1179  \end{equation*}%  \end{equation*}
1180  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.
1181    
1182  The heat equation is obtained by noting that  The heat equation is obtained by noting that
1183  \begin{equation*}  \begin{equation*}
1184  c_{p}\frac{DT}{Dt}=\frac{D(\Pi \theta )}{Dt}=\Pi \frac{D\theta }{Dt}+\theta  c_{p}\frac{DT}{Dt}=\frac{D(\Pi \theta )}{Dt}=\Pi \frac{D\theta }{Dt}+\theta
1185  \frac{D\Pi }{Dt}=\Pi \frac{D\theta }{Dt}+\alpha \frac{Dp}{Dt}  \frac{D\Pi }{Dt}=\Pi \frac{D\theta }{Dt}+\alpha \frac{Dp}{Dt}
1186  \end{equation*}  \end{equation*}
1187  and on substituting into (\ref{eq-p-heat-interim}) gives:  and on substituting into (\ref{eq-p-heat-interim}) gives:
1188  \begin{equation}  \begin{equation}
# Line 1090  and on substituting into (\ref{eq-p-heat Line 1191  and on substituting into (\ref{eq-p-heat
1191  \end{equation}  \end{equation}
1192  which is in conservative form.  which is in conservative form.
1193    
1194  For convenience in the model we prefer to step forward (\ref%  For convenience in the model we prefer to step forward (\ref
1195  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).
1196    
1197  \subsubsection{Boundary conditions}  \subsubsection{Boundary conditions}
# Line 1106  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 1134  _{o}(p_{o})=g~Z_{topo}$, defined: Line 1236  _{o}(p_{o})=g~Z_{topo}$, defined:
1236    
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 1154  We review here the method by which the s Line 1254  We review here the method by which the s
1254  HPE's for the ocean written in z-coordinates are obtained. The  HPE's for the ocean written in z-coordinates are obtained. The
1255  non-Boussinesq equations for oceanic motion are:  non-Boussinesq equations for oceanic motion are:
1256  \begin{eqnarray}  \begin{eqnarray}
1257  \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}}
1258  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\
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  \end{eqnarray}%  \label{eq:non-boussinesq}
1267    \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
1273  {eq-zns-salt}) and then using (\ref{eq-zns-eos}) to yield $\rho $. It is  {eq-zns-salt}) and then using (\ref{eq-zns-eos}) to yield $\rho $. It is
1274  therefore necessary to manipulate the system as follows. Differentiating the  therefore necessary to manipulate the system as follows. Differentiating the
1275  EOS (equation of state) gives:  EOS (equation of state) gives:
# Line 1180  _{\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}
1290  \end{equation}  \end{equation}
1291  where we have used an approximation sign to indicate that we have assumed  where we have used an approximation sign to indicate that we have assumed
# Line 1192  adiabatic motion, dropping the $\frac{D\ Line 1293  adiabatic motion, dropping the $\frac{D\
1293  Replacing \ref{eq-zns-cont} with \ref{eq-zns-pressure} yields a system that  Replacing \ref{eq-zns-cont} with \ref{eq-zns-pressure} yields a system that
1294  can be explicitly integrated forward:  can be explicitly integrated forward:
1295  \begin{eqnarray}  \begin{eqnarray}
1296  \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}}
1297  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}
1298  \label{eq-cns-hmom} \\  \label{eq-cns-hmom} \\
1299  \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}
1300  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\
1301  \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{
1302  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\
1303  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\
1304  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-cns-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-cns-heat} \\
# Line 1211  wherever it appears in a product (ie. no Line 1312  wherever it appears in a product (ie. no
1312  `Boussinesq assumption'. The only term that then retains the full variation  `Boussinesq assumption'. The only term that then retains the full variation
1313  in $\rho $ is the gravitational acceleration:  in $\rho $ is the gravitational acceleration:
1314  \begin{eqnarray}  \begin{eqnarray}
1315  \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}}
1316  _{h}+\frac{1}{\rho _{o}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\frac{1}{\rho _{o}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}
1317  \label{eq-zcb-hmom} \\  \label{eq-zcb-hmom} \\
1318  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}}%  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}}
1319  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1320  \label{eq-zcb-hydro} \\  \label{eq-zcb-hydro} \\
1321  \frac{1}{\rho _{o}c_{s}^{2}}\frac{Dp}{Dt}+\mathbf{\nabla }_{z}\cdot \vec{%  \frac{1}{\rho _{o}c_{s}^{2}}\frac{Dp}{Dt}+\mathbf{\nabla }_{z}\cdot \vec{
1322  \mathbf{v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-zcb-cont} \\  \mathbf{v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-zcb-cont} \\
1323  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\
1324  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\
1325  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}
1326  \end{eqnarray}  \end{eqnarray}
1327  These equations still retain acoustic modes. But, because the  These equations still retain acoustic modes. But, because the
1328  ``compressible'' terms are linearized, the pressure equation \ref%  ``compressible'' terms are linearized, the pressure equation \ref
1329  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent
1330  term appears as a Helmholtz term in the non-hydrostatic pressure equation).  term appears as a Helmholtz term in the non-hydrostatic pressure equation).
1331  These are the \emph{truly} compressible Boussinesq equations. Note that the  These are the \emph{truly} compressible Boussinesq equations. Note that the
1332  EOS must have the same pressure dependency as the linearized pressure term,  EOS must have the same pressure dependency as the linearized pressure term,
1333  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{%  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{
1334  c_{s}^{2}}$, for consistency.  c_{s}^{2}}$, for consistency.
1335    
1336  \subsubsection{`Anelastic' z-coordinate equations}  \subsubsection{`Anelastic' z-coordinate equations}
1337    
1338  The anelastic approximation filters the acoustic mode by removing the  The anelastic approximation filters the acoustic mode by removing the
1339  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}%  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}
1340  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}%  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}
1341  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between
1342  continuity and EOS. A better solution is to change the dependency on  continuity and EOS. A better solution is to change the dependency on
1343  pressure in the EOS by splitting the pressure into a reference function of  pressure in the EOS by splitting the pressure into a reference function of
1344  height and a perturbation:  height and a perturbation:
1345  \begin{equation*}  \begin{equation*}
1346  \rho =\rho (\theta ,S,p_{o}(z)+\epsilon _{s}p^{\prime })  \rho =\rho (\theta ,S,p_{o}(z)+\epsilon _{s}p^{\prime })
1347  \end{equation*}  \end{equation*}
1348  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from
1349  differentiating the EOS, the continuity equation then becomes:  differentiating the EOS, the continuity equation then becomes:
1350  \begin{equation*}  \begin{equation*}
1351  \frac{1}{\rho _{o}c_{s}^{2}}\left( \frac{Dp_{o}}{Dt}+\epsilon _{s}\frac{%  \frac{1}{\rho _{o}c_{s}^{2}}\left( \frac{Dp_{o}}{Dt}+\epsilon _{s}\frac{
1352  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+%  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+
1353  \frac{\partial w}{\partial z}=0  \frac{\partial w}{\partial z}=0
1354  \end{equation*}  \end{equation*}
1355  If the time- and space-scales of the motions of interest are longer than  If the time- and space-scales of the motions of interest are longer than
1356  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},%  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},
1357  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and
1358  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{%  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{
1359  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta
1360  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon
1361  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation
1362  and EOS. Expanding $\frac{Dp_{o}(z)}{Dt}=-g\rho _{o}w$ then leads to the  and EOS. Expanding $\frac{Dp_{o}(z)}{Dt}=-g\rho _{o}w$ then leads to the
1363  anelastic continuity equation:  anelastic continuity equation:
1364  \begin{equation}  \begin{equation}
1365  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}-%  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}-
1366  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}
1367  \end{equation}  \end{equation}
1368  A slightly different route leads to the quasi-Boussinesq continuity equation  A slightly different route leads to the quasi-Boussinesq continuity equation
1369  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+%  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+
1370  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }%  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }
1371  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:
1372  \begin{equation}  \begin{equation}
1373  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{%  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{
1374  \partial \left( \rho _{o}w\right) }{\partial z}=0  \label{eq-za-cont2}  \partial \left( \rho _{o}w\right) }{\partial z}=0  \label{eq-za-cont2}
1375  \end{equation}  \end{equation}
1376  Equations \ref{eq-za-cont1} and \ref{eq-za-cont2} are in fact the same  Equations \ref{eq-za-cont1} and \ref{eq-za-cont2} are in fact the same
# Line 1278  equation if: Line 1379  equation if:
1379  \frac{1}{\rho _{o}}\frac{\partial \rho _{o}}{\partial z}=\frac{-g}{c_{s}^{2}}  \frac{1}{\rho _{o}}\frac{\partial \rho _{o}}{\partial z}=\frac{-g}{c_{s}^{2}}
1380  \end{equation}  \end{equation}
1381  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$
1382  and $S_{o}$ profiles, then the EOS dependency on $p_{o}$ and the term $\frac{%  and $S_{o}$ profiles, then the EOS dependency on $p_{o}$ and the term $\frac{
1383  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The
1384  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are
1385  then:  then:
1386  \begin{eqnarray}  \begin{eqnarray}
1387  \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}}
1388  _{h}+\frac{1}{\rho _{o}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\frac{1}{\rho _{o}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}
1389  \label{eq-zab-hmom} \\  \label{eq-zab-hmom} \\
1390  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}}%  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}}
1391  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1392  \label{eq-zab-hydro} \\  \label{eq-zab-hydro} \\
1393  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{%  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{
1394  \partial \left( \rho _{o}w\right) }{\partial z} &=&0  \label{eq-zab-cont} \\  \partial \left( \rho _{o}w\right) }{\partial z} &=&0  \label{eq-zab-cont} \\
1395  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\
1396  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zab-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zab-heat} \\
# Line 1302  Here, the objective is to drop the depth Line 1403  Here, the objective is to drop the depth
1403  technically, to also remove the dependence of $\rho $ on $p_{o}$. This would  technically, to also remove the dependence of $\rho $ on $p_{o}$. This would
1404  yield the ``truly'' incompressible Boussinesq equations:  yield the ``truly'' incompressible Boussinesq equations:
1405  \begin{eqnarray}  \begin{eqnarray}
1406  \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}}
1407  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}
1408  \label{eq-ztb-hmom} \\  \label{eq-ztb-hmom} \\
1409  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{c}}+\frac{1}{\rho _{c}}%  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{c}}+\frac{1}{\rho _{c}}
1410  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1411  \label{eq-ztb-hydro} \\  \label{eq-ztb-hydro} \\
1412  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}
# Line 1324  retain compressibility effects in the de Line 1425  retain compressibility effects in the de
1425  density thus:  density thus:
1426  \begin{equation*}  \begin{equation*}
1427  \rho =\rho _{o}+\rho ^{\prime }  \rho =\rho _{o}+\rho ^{\prime }
1428  \end{equation*}%  \end{equation*}
1429  We then assert that variations with depth of $\rho _{o}$ are unimportant  We then assert that variations with depth of $\rho _{o}$ are unimportant
1430  while the compressible effects in $\rho ^{\prime }$ are:  while the compressible effects in $\rho ^{\prime }$ are:
1431  \begin{equation*}  \begin{equation*}
1432  \rho _{o}=\rho _{c}  \rho _{o}=\rho _{c}
1433  \end{equation*}%  \end{equation*}
1434  \begin{equation*}  \begin{equation*}
1435  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}
1436  \end{equation*}%  \end{equation*}
1437  This then yields what we can call the semi-compressible Boussinesq  This then yields what we can call the semi-compressible Boussinesq
1438  equations:  equations:
1439  \begin{eqnarray}  \begin{eqnarray}
1440  \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}}
1441  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{%  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{
1442  \mathcal{F}}}  \label{eq:ocean-mom} \\  \mathcal{F}}}  \label{eq:ocean-mom} \\
1443  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho ^{\prime }}{\rho _{c}}+\frac{1}{\rho  \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho ^{\prime }}{\rho _{c}}+\frac{1}{\rho
1444  _{c}}\frac{\partial p^{\prime }}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  _{c}}\frac{\partial p^{\prime }}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
# Line 1348  _{c}}\frac{\partial p^{\prime }}{\partia Line 1449  _{c}}\frac{\partial p^{\prime }}{\partia
1449  \\  \\
1450  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\
1451  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}
1452  \end{eqnarray}%  \end{eqnarray}
1453  Note that the hydrostatic pressure of the resting fluid, including that  Note that the hydrostatic pressure of the resting fluid, including that
1454  associated with $\rho _{c}$, is subtracted out since it has no effect on the  associated with $\rho _{c}$, is subtracted out since it has no effect on the
1455  dynamics.  dynamics.
# Line 1359  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 1372  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    
1503  %%%% \end{document}  %tci%\end{document}

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