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 %%%% \begin{document}  
 %%%%  
 %%%% \tableofcontents  
29    
30  \pagebreak  %tci%\begin{document}
31    
32    %tci%\tableofcontents
33    
 \part{MITgcm basics}  
34    
35  % Section: Overview  % Section: Overview
36    
37  % $Header$  % $Header$
38  % $Name$  % $Name$
39    
40  \section{Introduction}  This document provides the reader with the information necessary to
   
 This documentation provides the reader with the information necessary to  
41  carry out numerical experiments using MITgcm. It gives a comprehensive  carry out numerical experiments using MITgcm. It gives a comprehensive
42  description of the continuous equations on which the model is based, the  description of the continuous equations on which the model is based, the
43  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 47  are available. A number of examples illu
47  both process and general circulation studies of the atmosphere and ocean are  both process and general circulation studies of the atmosphere and ocean are
48  also presented.  also presented.
49    
50    \section{Introduction}
51    \begin{rawhtml}
52    <!-- CMIREDIR:innovations: -->
53    \end{rawhtml}
54    
55    
56  MITgcm has a number of novel aspects:  MITgcm has a number of novel aspects:
57    
58  \begin{itemize}  \begin{itemize}
59  \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
60  hydrodynamical kernel is used to drive forward both atmospheric and oceanic  hydrodynamical kernel is used to drive forward both atmospheric and oceanic
61  models - see fig.1%  models - see fig \ref{fig:onemodel}
62  \marginpar{  
63  Fig.1 One model}\ref{fig:onemodel}  %% CNHbegin
64    \input{part1/one_model_figure}
65  \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}  
66    
67  \item it has a non-hydrostatic capability and so can be used to study both  \item it has a non-hydrostatic capability and so can be used to study both
68  small-scale and large scale processes - see fig.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}  
69    
70    %% CNHbegin
71    \input{part1/all_scales_figure}
72    %% CNHend
73    
74  \item finite volume techniques are employed yielding an intuitive  \item finite volume techniques are employed yielding an intuitive
75  discretization and support for the treatment of irregular geometries using  discretization and support for the treatment of irregular geometries using
76  orthogonal curvilinear grids and shaved cells - see fig.3%  orthogonal curvilinear grids and shaved cells - see fig \ref{fig:finite-volumes}
77  \marginpar{  
78  Fig.3 Finite volumes}\ref{fig:Finite volumes}  %% CNHbegin
79    \input{part1/fvol_figure}
80    %% CNHend
81    
82  \item tangent linear and adjoint counterparts are automatically maintained  \item tangent linear and adjoint counterparts are automatically maintained
83  along with the forward model, permitting sensitivity and optimization  along with the forward model, permitting sensitivity and optimization
# Line 130  computational platforms. Line 88  computational platforms.
88  \end{itemize}  \end{itemize}
89    
90  Key publications reporting on and charting the development of the model are  Key publications reporting on and charting the development of the model are
91  listed in an Appendix.  \cite{hill:95,marshall:97a,marshall:97b,adcroft:97,marshall:98,adcroft:99,hill:99,maro-eta:99}:
92    
93    \begin{verbatim}
94    Hill, C. and J. Marshall, (1995)
95    Application of a Parallel Navier-Stokes Model to Ocean Circulation in
96    Parallel Computational Fluid Dynamics
97    In Proceedings of Parallel Computational Fluid Dynamics: Implementations
98    and Results Using Parallel Computers, 545-552.
99    Elsevier Science B.V.: New York
100    
101    Marshall, J., C. Hill, L. Perelman, and A. Adcroft, (1997)
102    Hydrostatic, quasi-hydrostatic, and nonhydrostatic ocean modeling
103    J. Geophysical Res., 102(C3), 5733-5752.
104    
105    Marshall, J., A. Adcroft, C. Hill, L. Perelman, and C. Heisey, (1997)
106    A finite-volume, incompressible Navier Stokes model for studies of the ocean
107    on parallel computers,
108    J. Geophysical Res., 102(C3), 5753-5766.
109    
110    Adcroft, A.J., Hill, C.N. and J. Marshall, (1997)
111    Representation of topography by shaved cells in a height coordinate ocean
112    model
113    Mon Wea Rev, vol 125, 2293-2315
114    
115    Marshall, J., Jones, H. and C. Hill, (1998)
116    Efficient ocean modeling using non-hydrostatic algorithms
117    Journal of Marine Systems, 18, 115-134
118    
119    Adcroft, A., Hill C. and J. Marshall: (1999)
120    A new treatment of the Coriolis terms in C-grid models at both high and low
121    resolutions,
122    Mon. Wea. Rev. Vol 127, pages 1928-1936
123    
124    Hill, C, Adcroft,A., Jamous,D., and J. Marshall, (1999)
125    A Strategy for Terascale Climate Modeling.
126    In Proceedings of the Eighth ECMWF Workshop on the Use of Parallel Processors
127    in Meteorology, pages 406-425
128    World Scientific Publishing Co: UK
129    
130    Marotzke, J, Giering,R., Zhang, K.Q., Stammer,D., Hill,C., and T.Lee, (1999)
131    Construction of the adjoint MIT ocean general circulation model and
132    application to Atlantic heat transport variability
133    J. Geophysical Res., 104(C12), 29,529-29,547.
134    
135    \end{verbatim}
136    
137  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
138  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  
139    
140  % $Header$  % $Header$
141  % $Name$  % $Name$
# Line 143  give a feel for the wide range of proble Line 144  give a feel for the wide range of proble
144    
145  The MITgcm has been designed and used to model a wide range of phenomena,  The MITgcm has been designed and used to model a wide range of phenomena,
146  from convection on the scale of meters in the ocean to the global pattern of  from convection on the scale of meters in the ocean to the global pattern of
147  atmospheric winds - see 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
148  kinds of problems the model has been used to study, we briefly describe some  kinds of problems the model has been used to study, we briefly describe some
149  of them here. A more detailed description of the underlying formulation,  of them here. A more detailed description of the underlying formulation,
150  numerical algorithm and implementation that lie behind these calculations is  numerical algorithm and implementation that lie behind these calculations is
151  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
152  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
153  with a FORTRAN\ 77 compiler) and follow the examples.  running Linux, together with a FORTRAN\ 77 compiler) and follow the examples
154    described in detail in the documentation.
155    
156  \subsection{Global atmosphere: `Held-Suarez' benchmark}  \subsection{Global atmosphere: `Held-Suarez' benchmark}
157    \begin{rawhtml}
158    <!-- CMIREDIR:atmospheric_example: -->
159    \end{rawhtml}
160    
 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}  
161    
 \subsection{Ocean gyres}  
162    
163  \subsection{Global ocean circulation}  A novel feature of MITgcm is its ability to simulate, using one basic algorithm,
164    both atmospheric and oceanographic flows at both small and large scales.
165  Fig.E2a shows the pattern of ocean currents at the surface of a 4$^{\circ }$  
166  global ocean model run with 15 vertical levels. The model is driven using  Figure \ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$
167  monthly-mean winds with mixed boundary conditions on temperature and  temperature field obtained using the atmospheric isomorph of MITgcm run at
168  salinity at the surface. Fig.E2b shows the overturning (thermohaline)  2.8$^{\circ }$ resolution on the cubed sphere. We see cold air over the pole
169  circulation. Lopped cells are used to represent topography on a regular $%  (blue) and warm air along an equatorial band (red). Fully developed
170  lat-lon$ grid extending from 70$^{\circ }N$ to 70$^{\circ }S$.  baroclinic eddies spawned in the northern hemisphere storm track are
171    evident. There are no mountains or land-sea contrast in this calculation,
172    but you can easily put them in. The model is driven by relaxation to a
173  \begin{figure}  radiative-convective equilibrium profile, following the description set out
174  \begin{center}  in Held and Suarez; 1994 designed to test atmospheric hydrodynamical cores -
175  \resizebox{!}{4in}{  there are no mountains or land-sea contrast.
176  % \rotatebox{90}{  
177    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/ocean_circ_455_2030.eps}  %% CNHbegin
178  % }  \input{part1/cubic_eddies_figure}
179  }  %% CNHend
180  \end{center}  
181  \label{fig:horizcirc}  As described in Adcroft (2001), a `cubed sphere' is used to discretize the
182  \end{figure}  globe permitting a uniform griding and obviated the need to Fourier filter.
183    The `vector-invariant' form of MITgcm supports any orthogonal curvilinear
184  \begin{figure}  grid, of which the cubed sphere is just one of many choices.
185  \begin{center}  
186  \resizebox{!}{4in}{  Figure \ref{fig:hs_zave_u} shows the 5-year mean, zonally averaged zonal
187   \rotatebox{90}{  wind from a 20-level configuration of
188   \rotatebox{180}{  the model. It compares favorable with more conventional spatial
189    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/moc.eps}  discretization approaches. The two plots show the field calculated using the
190   }  cube-sphere grid and the flow calculated using a regular, spherical polar
191   }  latitude-longitude grid. Both grids are supported within the model.
192  }  
193  \end{center}  %% CNHbegin
194  \label{fig:moc}  \input{part1/hs_zave_u_figure}
195  \end{figure}  %% CNHend
   
   
 \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}  
196    
197  \subsection{Carbon outgassing sensitivity}  \subsection{Ocean gyres}
198    \begin{rawhtml}
199    <!-- CMIREDIR:oceanic_example: -->
200    \end{rawhtml}
201    \begin{rawhtml}
202    <!-- CMIREDIR:ocean_gyres: -->
203    \end{rawhtml}
204    
205    Baroclinic instability is a ubiquitous process in the ocean, as well as the
206    atmosphere. Ocean eddies play an important role in modifying the
207    hydrographic structure and current systems of the oceans. Coarse resolution
208    models of the oceans cannot resolve the eddy field and yield rather broad,
209    diffusive patterns of ocean currents. But if the resolution of our models is
210    increased until the baroclinic instability process is resolved, numerical
211    solutions of a different and much more realistic kind, can be obtained.
212    
213    Figure \ref{fig:ocean-gyres} shows the surface temperature and velocity
214    field obtained from MITgcm run at $\frac{1}{6}^{\circ }$ horizontal
215    resolution on a $lat-lon$
216    grid in which the pole has been rotated by 90$^{\circ }$ on to the equator
217    (to avoid the converging of meridian in northern latitudes). 21 vertical
218    levels are used in the vertical with a `lopped cell' representation of
219    topography. The development and propagation of anomalously warm and cold
220    eddies can be clearly seen in the Gulf Stream region. The transport of
221    warm water northward by the mean flow of the Gulf Stream is also clearly
222    visible.
223    
224    %% CNHbegin
225    \input{part1/atl6_figure}
226    %% CNHend
227    
 Fig.E4 shows....  
228    
229  \begin{figure}  \subsection{Global ocean circulation}
230  \begin{center}  \begin{rawhtml}
231  \resizebox{!}{4in}{  <!-- CMIREDIR:global_ocean_circulation: -->
232    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/co209.eps}  \end{rawhtml}
233  }  
234  \end{center}  Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean currents at
235  \label{fig:co2mrt}  the surface of a 4$^{\circ }$
236  \end{figure}  global ocean model run with 15 vertical levels. Lopped cells are used to
237    represent topography on a regular $lat-lon$ grid extending from 70$^{\circ
238    }N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with
239    mixed boundary conditions on temperature and salinity at the surface. The
240    transfer properties of ocean eddies, convection and mixing is parameterized
241    in this model.
242    
243    Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning
244    circulation of the global ocean in Sverdrups.
245    
246    %%CNHbegin
247    \input{part1/global_circ_figure}
248    %%CNHend
249    
250    \subsection{Convection and mixing over topography}
251    \begin{rawhtml}
252    <!-- CMIREDIR:mixing_over_topography: -->
253    \end{rawhtml}
254    
255    
256    Dense plumes generated by localized cooling on the continental shelf of the
257    ocean may be influenced by rotation when the deformation radius is smaller
258    than the width of the cooling region. Rather than gravity plumes, the
259    mechanism for moving dense fluid down the shelf is then through geostrophic
260    eddies. The simulation shown in the figure \ref{fig:convect-and-topo}
261    (blue is cold dense fluid, red is
262    warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to
263    trigger convection by surface cooling. The cold, dense water falls down the
264    slope but is deflected along the slope by rotation. It is found that
265    entrainment in the vertical plane is reduced when rotational control is
266    strong, and replaced by lateral entrainment due to the baroclinic
267    instability of the along-slope current.
268    
269    %%CNHbegin
270    \input{part1/convect_and_topo}
271    %%CNHend
272    
273    \subsection{Boundary forced internal waves}
274    \begin{rawhtml}
275    <!-- CMIREDIR:boundary_forced_internal_waves: -->
276    \end{rawhtml}
277    
278    The unique ability of MITgcm to treat non-hydrostatic dynamics in the
279    presence of complex geometry makes it an ideal tool to study internal wave
280    dynamics and mixing in oceanic canyons and ridges driven by large amplitude
281    barotropic tidal currents imposed through open boundary conditions.
282    
283    Fig. \ref{fig:boundary-forced-wave} shows the influence of cross-slope
284    topographic variations on
285    internal wave breaking - the cross-slope velocity is in color, the density
286    contoured. The internal waves are excited by application of open boundary
287    conditions on the left. They propagate to the sloping boundary (represented
288    using MITgcm's finite volume spatial discretization) where they break under
289    nonhydrostatic dynamics.
290    
291    %%CNHbegin
292    \input{part1/boundary_forced_waves}
293    %%CNHend
294    
295    \subsection{Parameter sensitivity using the adjoint of MITgcm}
296    \begin{rawhtml}
297    <!-- CMIREDIR:parameter_sensitivity: -->
298    \end{rawhtml}
299    
300    Forward and tangent linear counterparts of MITgcm are supported using an
301    `automatic adjoint compiler'. These can be used in parameter sensitivity and
302    data assimilation studies.
303    
304    As one example of application of the MITgcm adjoint, Figure \ref{fig:hf-sensitivity}
305    maps the gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude
306    of the overturning stream-function shown in figure \ref{fig:large-scale-circ}
307    at 60$^{\circ }$N and $
308    \mathcal{H}(\lambda,\varphi)$ is the mean, local air-sea heat flux over
309    a 100 year period. We see that $J$ is
310    sensitive to heat fluxes over the Labrador Sea, one of the important sources
311    of deep water for the thermohaline circulations. This calculation also
312    yields sensitivities to all other model parameters.
313    
314    %%CNHbegin
315    \input{part1/adj_hf_ocean_figure}
316    %%CNHend
317    
318    \subsection{Global state estimation of the ocean}
319    \begin{rawhtml}
320    <!-- CMIREDIR:global_state_estimation: -->
321    \end{rawhtml}
322    
323    
324    An important application of MITgcm is in state estimation of the global
325    ocean circulation. An appropriately defined `cost function', which measures
326    the departure of the model from observations (both remotely sensed and
327    in-situ) over an interval of time, is minimized by adjusting `control
328    parameters' such as air-sea fluxes, the wind field, the initial conditions
329    etc. Figure \ref{fig:assimilated-globes} shows the large scale planetary
330    circulation and a Hopf-Muller plot of Equatorial sea-surface height.
331    Both are obtained from assimilation bringing the model in to
332    consistency with altimetric and in-situ observations over the period
333    1992-1997.
334    
335    %% CNHbegin
336    \input{part1/assim_figure}
337    %% CNHend
338    
339    \subsection{Ocean biogeochemical cycles}
340    \begin{rawhtml}
341    <!-- CMIREDIR:ocean_biogeo_cycles: -->
342    \end{rawhtml}
343    
344    MITgcm is being used to study global biogeochemical cycles in the ocean. For
345    example one can study the effects of interannual changes in meteorological
346    forcing and upper ocean circulation on the fluxes of carbon dioxide and
347    oxygen between the ocean and atmosphere. Figure \ref{fig:biogeo} shows
348    the annual air-sea flux of oxygen and its relation to density outcrops in
349    the southern oceans from a single year of a global, interannually varying
350    simulation. The simulation is run at $1^{\circ}\times1^{\circ}$ resolution
351    telescoping to $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not shown).
352    
353    %%CNHbegin
354    \input{part1/biogeo_figure}
355    %%CNHend
356    
357    \subsection{Simulations of laboratory experiments}
358    \begin{rawhtml}
359    <!-- CMIREDIR:classroom_exp: -->
360    \end{rawhtml}
361    
362    Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a
363    laboratory experiment inquiring into the dynamics of the Antarctic Circumpolar Current (ACC). An
364    initially homogeneous tank of water ($1m$ in diameter) is driven from its
365    free surface by a rotating heated disk. The combined action of mechanical
366    and thermal forcing creates a lens of fluid which becomes baroclinically
367    unstable. The stratification and depth of penetration of the lens is
368    arrested by its instability in a process analogous to that which sets the
369    stratification of the ACC.
370    
371    %%CNHbegin
372    \input{part1/lab_figure}
373    %%CNHend
374    
375  % $Header$  % $Header$
376  % $Name$  % $Name$
377    
378  \section{Continuous equations in `r' coordinates}  \section{Continuous equations in `r' coordinates}
379    \begin{rawhtml}
380    <!-- CMIREDIR:z-p_isomorphism: -->
381    \end{rawhtml}
382    
383  To render atmosphere and ocean models from one dynamical core we exploit  To render atmosphere and ocean models from one dynamical core we exploit
384  `isomorphisms' between equation sets that govern the evolution of the  `isomorphisms' between equation sets that govern the evolution of the
385  respective fluids - see fig.4%  respective fluids - see figure \ref{fig:isomorphic-equations}.
386  \marginpar{  One system of hydrodynamical equations is written down
 Fig.4. Isomorphisms}. One system of hydrodynamical equations is written down  
387  and encoded. The model variables have different interpretations depending on  and encoded. The model variables have different interpretations depending on
388  whether the atmosphere or ocean is being studied. Thus, for example, the  whether the atmosphere or ocean is being studied. Thus, for example, the
389  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are
390  modeling the atmosphere and height, $z$, if we are modeling the ocean.  modeling the atmosphere (right hand side of figure \ref{fig:isomorphic-equations})
391    and height, $z$, if we are modeling the ocean (left hand side of figure
392    \ref{fig:isomorphic-equations}).
393    
394    %%CNHbegin
395    \input{part1/zandpcoord_figure.tex}
396    %%CNHend
397    
398  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
399  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 401  velocity $\vec{\mathbf{v}}$, active trac
401  depend on $\theta $, $S$, and $p$. The equations that govern the evolution  depend on $\theta $, $S$, and $p$. The equations that govern the evolution
402  of these fields, obtained by applying the laws of classical mechanics and  of these fields, obtained by applying the laws of classical mechanics and
403  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of
404  a generic vertical coordinate, $r$, see fig.5%  a generic vertical coordinate, $r$, so that the appropriate
405  \marginpar{  kinematic boundary conditions can be applied isomorphically
406  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*}  
407    
408  \begin{equation*}  %%CNHbegin
409  \frac{D\dot{r}}{Dt}+\widehat{k}\cdot \left( 2\vec{\Omega}\times \vec{\mathbf{%  \input{part1/vertcoord_figure.tex}
410    %%CNHend
411    
412    \begin{equation}
413    \frac{D\vec{\mathbf{v}_{h}}}{Dt}+\left( 2\vec{\Omega}\times \vec{\mathbf{v}}
414    \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}
415    \text{ horizontal mtm} \label{eq:horizontal_mtm}
416    \end{equation}
417    
418    \begin{equation}
419    \frac{D\dot{r}}{Dt}+\widehat{k}\cdot \left( 2\vec{\Omega}\times \vec{\mathbf{
420  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{
421  vertical mtm}  vertical mtm} \label{eq:vertical_mtm}
422  \end{equation*}  \end{equation}
423    
424  \begin{equation}  \begin{equation}
425  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{%  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{
426  \partial r}=0\text{ continuity}  \label{eq:continuous}  \partial r}=0\text{ continuity}  \label{eq:continuity}
427  \end{equation}  \end{equation}
428    
429  \begin{equation*}  \begin{equation}
430  b=b(\theta ,S,r)\text{ equation of state}  b=b(\theta ,S,r)\text{ equation of state} \label{eq:equation_of_state}
431  \end{equation*}  \end{equation}
432    
433  \begin{equation*}  \begin{equation}
434  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{  potential temperature}  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature}
435  \end{equation*}  \label{eq:potential_temperature}
436    \end{equation}
437    
438  \begin{equation*}  \begin{equation}
439  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{  humidity/salinity}  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity}
440  \end{equation*}  \label{eq:humidity_salt}
441    \end{equation}
442    
443  Here:  Here:
444    
445  \begin{equation*}  \begin{equation*}
446  r\text{ is the vertical coordinate}  r\text{ is the vertical coordinate}
447  \end{equation*}  \end{equation*}
448    
449  \begin{equation*}  \begin{equation*}
450  \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{
451  is the total derivative}  is the total derivative}
452  \end{equation*}  \end{equation*}
453    
454  \begin{equation*}  \begin{equation*}
455  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}%  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}
456  \text{ is the `grad' operator}  \text{ is the `grad' operator}
457  \end{equation*}  \end{equation*}
458  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}%  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}
459  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$
460  is a unit vector in the vertical  is a unit vector in the vertical
461    
462  \begin{equation*}  \begin{equation*}
463  t\text{ is time}  t\text{ is time}
464  \end{equation*}  \end{equation*}
465    
466  \begin{equation*}  \begin{equation*}
467  \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
468  velocity}  velocity}
469  \end{equation*}  \end{equation*}
470    
471  \begin{equation*}  \begin{equation*}
472  \phi \text{ is the `pressure'/`geopotential'}  \phi \text{ is the `pressure'/`geopotential'}
473  \end{equation*}  \end{equation*}
474    
475  \begin{equation*}  \begin{equation*}
476  \vec{\Omega}\text{ is the Earth's rotation}  \vec{\Omega}\text{ is the Earth's rotation}
477  \end{equation*}  \end{equation*}
478    
479  \begin{equation*}  \begin{equation*}
480  b\text{ is the `buoyancy'}  b\text{ is the `buoyancy'}
481  \end{equation*}  \end{equation*}
482    
483  \begin{equation*}  \begin{equation*}
484  \theta \text{ is potential temperature}  \theta \text{ is potential temperature}
485  \end{equation*}  \end{equation*}
486    
487  \begin{equation*}  \begin{equation*}
488  S\text{ is specific humidity in the atmosphere; salinity in the ocean}  S\text{ is specific humidity in the atmosphere; salinity in the ocean}
489  \end{equation*}  \end{equation*}
490    
491  \begin{equation*}  \begin{equation*}
492  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{%  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{
493  \mathbf{v}}  \mathbf{v}}
494  \end{equation*}  \end{equation*}
495    
496  \begin{equation*}  \begin{equation*}
497  \mathcal{Q}_{\theta }\mathcal{\ }\text{are forcing and dissipation of }%  \mathcal{Q}_{\theta }\mathcal{\ }\text{are forcing and dissipation of }\theta
 \theta  
498  \end{equation*}  \end{equation*}
499    
500  \begin{equation*}  \begin{equation*}
# Line 385  S\text{ is specific humidity in the atmo Line 502  S\text{ is specific humidity in the atmo
502  \end{equation*}  \end{equation*}
503    
504  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
505  extensive `physics' packages for atmosphere and ocean described in Chapter 6.  `physics' and forcing packages for atmosphere and ocean. These are described
506    in later chapters.
507    
508  \subsection{Kinematic Boundary conditions}  \subsection{Kinematic Boundary conditions}
509    
510  \subsubsection{vertical}  \subsubsection{vertical}
511    
512  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}):
513    
514  \begin{equation}  \begin{equation}
515  \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)}
516  \label{eq:fixedbc}  \label{eq:fixedbc}
517  \end{equation}  \end{equation}
518    
519  \begin{equation}  \begin{equation}
520  \dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \  \dot{r}=\frac{Dr}{Dt} \text{\ at\ } r=R_{moving}\text{ \
521  (oceansurface,bottomoftheatmosphere)}  \label{eq:movingbc}  (ocean surface,bottom of the atmosphere)}  \label{eq:movingbc}
522  \end{equation}  \end{equation}
523    
524  Here  Here
525    
526  \begin{equation*}  \begin{equation*}
527  R_{moving}=R_{o}+\eta  R_{moving}=R_{o}+\eta
528  \end{equation*}  \end{equation*}
529  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
530  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 535  of motion.
535    
536  \begin{equation}  \begin{equation}
537  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}
538  \end{equation}%  \end{equation}
539  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.
540    
541  \subsection{Atmosphere}  \subsection{Atmosphere}
542    
543  In the atmosphere, see fig.5, we interpret:  In the atmosphere, (see figure \ref{fig:zandp-vert-coord}), we interpret:
544    
545  \begin{equation}  \begin{equation}
546  r=p\text{ is the pressure}  \label{eq:atmos-r}  r=p\text{ is the pressure}  \label{eq:atmos-r}
# Line 454  where Line 572  where
572    
573  \begin{equation*}  \begin{equation*}
574  T\text{ is absolute temperature}  T\text{ is absolute temperature}
575  \end{equation*}%  \end{equation*}
576  \begin{equation*}  \begin{equation*}
577  p\text{ is the pressure}  p\text{ is the pressure}
578  \end{equation*}%  \end{equation*}
579  \begin{eqnarray*}  \begin{eqnarray*}
580  &&z\text{ is the height of the pressure surface} \\  &&z\text{ is the height of the pressure surface} \\
581  &&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 585  In the above the ideal gas law, $p=\rho
585  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)
586  \begin{equation}  \begin{equation}
587  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}
588  \end{equation}%  \end{equation}
589  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
590  constant and $c_{p}$ the specific heat of air at constant pressure.  constant and $c_{p}$ the specific heat of air at constant pressure.
591    
592  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):
593    
594  \begin{equation*}  \begin{equation*}
595  R_{fixed}=p_{top}=0  R_{fixed}=p_{top}=0
596  \end{equation*}  \end{equation*}
597  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
598  given by  given by
599  \begin{equation*}  \begin{equation*}
600  R_{moving}=R_{o}(x,y)=p_{o}(x,y)  R_{moving}=R_{o}(x,y)=p_{o}(x,y)
601  \end{equation*}  \end{equation*}
602  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
603  atmosphere.  atmosphere.
# Line 493  The boundary conditions at top and botto Line 611  The boundary conditions at top and botto
611  atmosphere)}  \label{eq:moving-bc-atmos}  atmosphere)}  \label{eq:moving-bc-atmos}
612  \end{eqnarray}  \end{eqnarray}
613    
614  Then the (hydrostatic form of) eq(\ref{eq:continuous}) yields a consistent  Then the (hydrostatic form of) equations (\ref{eq:horizontal_mtm}-\ref{eq:humidity_salt})
615  set of atmospheric equations which, for convenience, are written out in $p$  yields a consistent set of atmospheric equations which, for convenience, are written out in $p$
616  coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}).  coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}).
617    
618  \subsection{Ocean}  \subsection{Ocean}
# Line 517  At the bottom of the ocean: $R_{fixed}(x Line 635  At the bottom of the ocean: $R_{fixed}(x
635    
636  The surface of the ocean is given by: $R_{moving}=\eta $  The surface of the ocean is given by: $R_{moving}=\eta $
637    
638  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 $
639  R_{o}=Z_{o}=0$.  R_{o}=Z_{o}=0$.
640    
641  Boundary conditions are:  Boundary conditions are:
# Line 525  Boundary conditions are: Line 643  Boundary conditions are:
643  \begin{eqnarray}  \begin{eqnarray}
644  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}
645  \\  \\
646  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)
647  \label{eq:moving-bc-ocean}}  \label{eq:moving-bc-ocean}}
648  \end{eqnarray}  \end{eqnarray}
649  where $\eta $ is the elevation of the free surface.  where $\eta $ is the elevation of the free surface.
650    
651  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
652    of oceanic equations
653  which, for convenience, are written out in $z$ coordinates in Appendix Ocean  which, for convenience, are written out in $z$ coordinates in Appendix Ocean
654  - see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}).  - see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}).
655    
656  \subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and  \subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and
657  Non-hydrostatic forms}  Non-hydrostatic forms}
658    \begin{rawhtml}
659    <!-- CMIREDIR:non_hydrostatic: -->
660    \end{rawhtml}
661    
662    
663  Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms:  Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms:
664    
665  \begin{equation}  \begin{equation}
666  \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)
667  \label{eq:phi-split}  \label{eq:phi-split}
668  \end{equation}%  \end{equation}
669  and write eq(\ref{incompressible}a,b) in the form:  %and write eq(\ref{eq:incompressible}) in the form:
670    %                  ^- this eq is missing (jmc) ; replaced with:
671    and write eq( \ref{eq:horizontal_mtm}) in the form:
672    
673  \begin{equation}  \begin{equation}
674  \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 681  _{nh}=\vec{\mathbf{G}}_{\vec{v}_{h}}  \l
681  \end{equation}  \end{equation}
682    
683  \begin{equation}  \begin{equation}
684  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{%  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{
685  \partial r}=G_{\dot{r}}  \label{eq:mom-w}  \partial r}=G_{\dot{r}}  \label{eq:mom-w}
686  \end{equation}  \end{equation}
687  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.
688    
689  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
690  {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
691  terms in the momentum equations. In spherical coordinates they take the form%  terms in the momentum equations. In spherical coordinates they take the form
692  \footnote{%  \footnote{
693  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms
694  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref%  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref
695  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in
696  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (%  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (
697  \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
698  discussion:  discussion:
699    
# Line 576  discussion: Line 701  discussion:
701  \left.  \left.
702  \begin{tabular}{l}  \begin{tabular}{l}
703  $G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\  $G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\
704  $-\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\} $
705  \\  \\
706  $-\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\} $
707  \\  \\
708  $+\mathcal{F}_{u}$%  $+\mathcal{F}_{u}$
709  \end{tabular}%  \end{tabular}
710  \ \right\} \left\{  \ \right\} \left\{
711  \begin{tabular}{l}  \begin{tabular}{l}
712  \textit{advection} \\  \textit{advection} \\
713  \textit{metric} \\  \textit{metric} \\
714  \textit{Coriolis} \\  \textit{Coriolis} \\
715  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
716  \end{tabular}%  \end{tabular}
717  \ \right. \qquad   \label{eq:gu-speherical}  \ \right. \qquad  \label{eq:gu-speherical}
718  \end{equation}  \end{equation}
719    
720  \begin{equation}  \begin{equation}
721  \left.  \left.
722  \begin{tabular}{l}  \begin{tabular}{l}
723  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\
724  $-\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\}
725  $ \\  $ \\
726  $-\left\{ -2\Omega u\sin lat\right\} $ \\  $-\left\{ -2\Omega u\sin \varphi \right\} $ \\
727  $+\mathcal{F}_{v}$%  $+\mathcal{F}_{v}$
728  \end{tabular}%  \end{tabular}
729  \ \right\} \left\{  \ \right\} \left\{
730  \begin{tabular}{l}  \begin{tabular}{l}
731  \textit{advection} \\  \textit{advection} \\
732  \textit{metric} \\  \textit{metric} \\
733  \textit{Coriolis} \\  \textit{Coriolis} \\
734  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
735  \end{tabular}%  \end{tabular}
736  \ \right. \qquad   \label{eq:gv-spherical}  \ \right. \qquad  \label{eq:gv-spherical}
737  \end{equation}%  \end{equation}
738  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
739    
740  \begin{equation}  \begin{equation}
741  \left.  \left.
742  \begin{tabular}{l}  \begin{tabular}{l}
743  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\
744  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\
745  ${+}\underline{{2\Omega u\cos lat}}$ \\  ${+}\underline{{2\Omega u\cos \varphi}}$ \\
746  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$%  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$
747  \end{tabular}%  \end{tabular}
748  \ \right\} \left\{  \ \right\} \left\{
749  \begin{tabular}{l}  \begin{tabular}{l}
750  \textit{advection} \\  \textit{advection} \\
751  \textit{metric} \\  \textit{metric} \\
752  \textit{Coriolis} \\  \textit{Coriolis} \\
753  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
754  \end{tabular}%  \end{tabular}
755  \ \right.   \label{eq:gw-spherical}  \ \right.  \label{eq:gw-spherical}
756  \end{equation}%  \end{equation}
757  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
758    
759  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 `$\varphi$
760  ' is latitude.  ' is latitude.
761    
762  Grad and div operators in spherical coordinates are defined in appendix  Grad and div operators in spherical coordinates are defined in appendix
763  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}  
764    
765    %%CNHbegin
766    \input{part1/sphere_coord_figure.tex}
767    %%CNHend
768    
769  \subsubsection{Shallow atmosphere approximation}  \subsubsection{Shallow atmosphere approximation}
770    
# Line 661  hydrostatic balance and the `traditional Line 774  hydrostatic balance and the `traditional
774  Coriolis force is treated approximately and the shallow atmosphere  Coriolis force is treated approximately and the shallow atmosphere
775  approximation is made.\ The MITgcm need not make the `traditional  approximation is made.\ The MITgcm need not make the `traditional
776  approximation'. To be able to support consistent non-hydrostatic forms the  approximation'. To be able to support consistent non-hydrostatic forms the
777  shallow atmosphere approximation can be relaxed - when dividing through by $r  shallow atmosphere approximation can be relaxed - when dividing through by $
778  $ in, for example, (\ref{eq:gu-speherical}), we do not replace $r$ by $a$,  r $ in, for example, (\ref{eq:gu-speherical}), we do not replace $r$ by $a$,
779  the radius of the earth.  the radius of the earth.
780    
781  \subsubsection{Hydrostatic and quasi-hydrostatic forms}  \subsubsection{Hydrostatic and quasi-hydrostatic forms}
782    \label{sec:hydrostatic_and_quasi-hydrostatic_forms}
783    
784  These are discussed at length in Marshall et al (1997a).  These are discussed at length in Marshall et al (1997a).
785    
# Line 674  terms in Eqs. (\ref{eq:gu-speherical} $\ Line 788  terms in Eqs. (\ref{eq:gu-speherical} $\
788  are neglected and `${r}$' is replaced by `$a$', the mean radius of the  are neglected and `${r}$' is replaced by `$a$', the mean radius of the
789  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
790  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
791  computed at all other levels by integration of the hydrostatic relation, eq(%  computed at all other levels by integration of the hydrostatic relation, eq(
792  \ref{eq:hydrostatic}).  \ref{eq:hydrostatic}).
793    
794  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between
795  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
796  \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
797  contribution to the pressure field: only the terms underlined twice in Eqs. (%  contribution to the pressure field: only the terms underlined twice in Eqs. (
798  \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
799  and, simultaneously, the shallow atmosphere approximation is relaxed. In  and, simultaneously, the shallow atmosphere approximation is relaxed. In
800  \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 802  variation of the radial position of a pa
802  vertical momentum equation (\ref{eq:mom-w}) becomes:  vertical momentum equation (\ref{eq:mom-w}) becomes:
803    
804  \begin{equation*}  \begin{equation*}
805  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos \varphi
806  \end{equation*}  \end{equation*}
807  making a small correction to the hydrostatic pressure.  making a small correction to the hydrostatic pressure.
808    
# Line 704  only a quasi-non-hydrostatic atmospheric Line 818  only a quasi-non-hydrostatic atmospheric
818    
819  \paragraph{Non-hydrostatic Ocean}  \paragraph{Non-hydrostatic Ocean}
820    
821  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref%  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref
822  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A
823  three dimensional elliptic equation must be solved subject to Neumann  three dimensional elliptic equation must be solved subject to Neumann
824  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
825  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
826  incompressible condition eq(\ref{eq:continuous})c has already filtered out  incompressible condition eq(\ref{eq:continuity}) has already filtered out
827  acoustic modes. It does, however, ensure that the gravity waves are treated  acoustic modes. It does, however, ensure that the gravity waves are treated
828  accurately with an exact dispersion relation. The \textbf{NH} set has a  accurately with an exact dispersion relation. The \textbf{NH} set has a
829  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 831  and Bromley, 1995; Marshall et.al.\ 1997
831    
832  \paragraph{Quasi-nonhydrostatic Atmosphere}  \paragraph{Quasi-nonhydrostatic Atmosphere}
833    
834  In the non-hydrostatic version of our atmospheric model we approximate $\dot{%  In the non-hydrostatic version of our atmospheric model we approximate $\dot{
835  r}$ 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})
836  (but only here) by:  (but only here) by:
837    
838  \begin{equation}  \begin{equation}
839  \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}
840  \end{equation}%  \end{equation}
841  where $p_{hy}$ is the hydrostatic pressure.  where $p_{hy}$ is the hydrostatic pressure.
842    
843  \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 865  equations in $z-$coordinates are support
865    
866  \subparagraph{Non-hydrostatic}  \subparagraph{Non-hydrostatic}
867    
868  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$%  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$
869  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref%  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref
870  {eq:ocean-salt}).  {eq:ocean-salt}).
871    
872  \subsection{Solution strategy}  \subsection{Solution strategy}
873    
874  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{
875  NH} models is summarized in Fig.7.%  NH} models is summarized in Figure \ref{fig:solution-strategy}.
876  \marginpar{  Under all dynamics, a 2-d elliptic equation is
 Fig.7 Solution strategy} Under all dynamics, a 2-d elliptic equation is  
877  first solved to find the surface pressure and the hydrostatic pressure at  first solved to find the surface pressure and the hydrostatic pressure at
878  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
879  \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 882  forward and $\dot{r}$ found from continu
882  stepping forward the horizontal momentum equations; $\dot{r}$ is found by  stepping forward the horizontal momentum equations; $\dot{r}$ is found by
883  stepping forward the vertical momentum equation.  stepping forward the vertical momentum equation.
884    
885  \begin{figure}  %%CNHbegin
886  \begin{center}  \input{part1/solution_strategy_figure.tex}
887  \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}  
   
888    
889  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
890  course, some complication that goes with the inclusion of $\cos \phi \ $%  course, some complication that goes with the inclusion of $\cos \varphi \ $
891  Coriolis terms and the relaxation of the shallow atmosphere approximation.  Coriolis terms and the relaxation of the shallow atmosphere approximation.
892  But this leads to negligible increase in computation. In \textbf{NH}, in  But this leads to negligible increase in computation. In \textbf{NH}, in
893  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 897  Marshall et al, 1997) resulting in a non
897  hydrostatic limit, is as computationally economic as the \textbf{HPEs}.  hydrostatic limit, is as computationally economic as the \textbf{HPEs}.
898    
899  \subsection{Finding the pressure field}  \subsection{Finding the pressure field}
900    \label{sec:finding_the_pressure_field}
901    
902  Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the  Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the
903  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 912  Hydrostatic pressure is obtained by inte
912  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:
913    
914  \begin{equation*}  \begin{equation*}
915  \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}
916  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr
917  \end{equation*}  \end{equation*}
918  and so  and so
919    
# Line 826  atmospheric pressure pushing down on the Line 930  atmospheric pressure pushing down on the
930    
931  \subsubsection{Surface pressure}  \subsubsection{Surface pressure}
932    
933  The surface pressure equation can be obtained by integrating continuity, (%  The surface pressure equation can be obtained by integrating continuity,
934  \ref{eq:continuous})c, vertically from $r=R_{fixed}$ to $r=R_{moving}$  (\ref{eq:continuity}), vertically from $r=R_{fixed}$ to $r=R_{moving}$
935    
936  \begin{equation*}  \begin{equation*}
937  \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}
938  }_{h}+\partial _{r}\dot{r}\right) dr=0  }_{h}+\partial _{r}\dot{r}\right) dr=0
939  \end{equation*}  \end{equation*}
940    
941  Thus:  Thus:
942    
943  \begin{equation*}  \begin{equation*}
944  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta
945  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}%  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}
946  _{h}dr=0  _{h}dr=0
947  \end{equation*}  \end{equation*}
948  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 $
949  r $. The above can be rearranged to yield, using Leibnitz's theorem:  r $. The above can be rearranged to yield, using Leibnitz's theorem:
950    
951  \begin{equation}  \begin{equation}
952  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot
953  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}
954  \label{eq:free-surface}  \label{eq:free-surface}
955  \end{equation}%  \end{equation}
956  where we have incorporated a source term.  where we have incorporated a source term.
957    
958  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential
959  (atmospheric model), in (\ref{mtm-split}), the horizontal gradient term can  (atmospheric model), in (\ref{eq:mom-h}), the horizontal gradient term can
960  be written  be written
961  \begin{equation}  \begin{equation}
962  \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)
963  \label{eq:phi-surf}  \label{eq:phi-surf}
964  \end{equation}%  \end{equation}
965  where $b_{s}$ is the buoyancy at the surface.  where $b_{s}$ is the buoyancy at the surface.
966    
967  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
968  {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
969  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free
970  surface' and `rigid lid' approaches are available.  surface' and `rigid lid' approaches are available.
971    
972  \subsubsection{Non-hydrostatic pressure}  \subsubsection{Non-hydrostatic pressure}
973    
974  Taking the horizontal divergence of (\ref{hor-mtm}) and adding $\frac{%  Taking the horizontal divergence of (\ref{eq:mom-h}) and adding
975  \partial }{\partial r}$ of (\ref{vertmtm}), invoking the continuity equation  $\frac{\partial }{\partial r}$ of (\ref{eq:mom-w}), invoking the continuity equation
976  (\ref{incompressible}), we deduce that:  (\ref{eq:continuity}), we deduce that:
977    
978  \begin{equation}  \begin{equation}
979  \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{
980  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .%  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .
981  \vec{\mathbf{F}}  \label{eq:3d-invert}  \vec{\mathbf{F}}  \label{eq:3d-invert}
982  \end{equation}  \end{equation}
983    
# Line 893  coasts (in the ocean) and the bottom: Line 997  coasts (in the ocean) and the bottom:
997  \end{equation}  \end{equation}
998  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
999  kinematic condition (\ref{nonormalflow}) is also applied to the vertical  kinematic condition (\ref{nonormalflow}) is also applied to the vertical
1000  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 $
1001  \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
1002  tangential component of velocity, $v_{T}$, at all solid boundaries,  tangential component of velocity, $v_{T}$, at all solid boundaries,
1003  depending on the form chosen for the dissipative terms in the momentum  depending on the form chosen for the dissipative terms in the momentum
1004  equations - see below.  equations - see below.
1005    
1006  Eq.(\ref{nonormalflow}) implies, making use of (\ref{mtm-split}), that:  Eq.(\ref{nonormalflow}) implies, making use of (\ref{eq:mom-h}), that:
1007    
1008  \begin{equation}  \begin{equation}
1009  \widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}}  \widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}}
# Line 910  where Line 1014  where
1014  \begin{equation*}  \begin{equation*}
1015  \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
1016  _{s}+\mathbf{\nabla }\phi _{hyd}\right)  _{s}+\mathbf{\nabla }\phi _{hyd}\right)
1017  \end{equation*}%  \end{equation*}
1018  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem
1019  (\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
1020  exploit classical 3D potential theory and, by introducing an appropriately  exploit classical 3D potential theory and, by introducing an appropriately
1021  chosen $\delta $-function sheet of `source-charge', replace the inhomogenous  chosen $\delta $-function sheet of `source-charge', replace the
1022  boundary condition on pressure by a homogeneous one. The source term $rhs$  inhomogeneous boundary condition on pressure by a homogeneous one. The
1023  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 $
1024  By simultaneously setting $%  \vec{\mathbf{F}}.$ By simultaneously setting $
1025  \begin{array}{l}  \begin{array}{l}
1026  \widehat{n}.\vec{\mathbf{F}}%  \widehat{n}.\vec{\mathbf{F}}
1027  \end{array}%  \end{array}
1028  =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
1029  self-consistent but simpler homogenised Elliptic problem is obtained:  self-consistent but simpler homogenized Elliptic problem is obtained:
1030    
1031  \begin{equation*}  \begin{equation*}
1032  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad
1033  \end{equation*}%  \end{equation*}
1034  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such
1035  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
1036  {eq:inhom-neumann-nh}) the modified boundary condition becomes:  {eq:inhom-neumann-nh}) the modified boundary condition becomes:
1037    
1038  \begin{equation}  \begin{equation}
# Line 939  If the flow is `close' to hydrostatic ba Line 1043  If the flow is `close' to hydrostatic ba
1043  converges rapidly because $\phi _{nh}\ $is then only a small correction to  converges rapidly because $\phi _{nh}\ $is then only a small correction to
1044  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).
1045    
1046  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})
1047  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.
1048    
1049  \subsection{Forcing/dissipation}  \subsection{Forcing/dissipation}
# Line 947  does not vanish at $r=R_{moving}$, and s Line 1051  does not vanish at $r=R_{moving}$, and s
1051  \subsubsection{Forcing}  \subsubsection{Forcing}
1052    
1053  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
1054  `physics packages' described in detail in chapter ??.  `physics packages' and forcing packages. These are described later on.
1055    
1056  \subsubsection{Dissipation}  \subsubsection{Dissipation}
1057    
# Line 957  Many forms of momentum dissipation are a Line 1061  Many forms of momentum dissipation are a
1061  biharmonic frictions are commonly used:  biharmonic frictions are commonly used:
1062    
1063  \begin{equation}  \begin{equation}
1064  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}}
1065  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}
1066  \end{equation}  \end{equation}
1067  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 1072  friction. These coefficients are the sam
1072    
1073  The mixing terms for the temperature and salinity equations have a similar  The mixing terms for the temperature and salinity equations have a similar
1074  form to that of momentum except that the diffusion tensor can be  form to that of momentum except that the diffusion tensor can be
1075  non-diagonal and have varying coefficients. $\qquad $%  non-diagonal and have varying coefficients. $\qquad $
1076  \begin{equation}  \begin{equation}
1077  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
1078  _{h}^{4}(T,S)  \label{eq:diffusion}  _{h}^{4}(T,S)  \label{eq:diffusion}
1079  \end{equation}  \end{equation}
1080  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $%  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $
1081  horizontal coefficient for biharmonic diffusion. In the simplest case where  horizontal coefficient for biharmonic diffusion. In the simplest case where
1082  the subgrid-scale fluxes of heat and salt are parameterized with constant  the subgrid-scale fluxes of heat and salt are parameterized with constant
1083  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 1088  reduces to a diagonal matrix with consta
1088  \begin{array}{ccc}  \begin{array}{ccc}
1089  K_{h} & 0 & 0 \\  K_{h} & 0 & 0 \\
1090  0 & K_{h} & 0 \\  0 & K_{h} & 0 \\
1091  0 & 0 & K_{v}%  0 & 0 & K_{v}
1092  \end{array}  \end{array}
1093  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}
1094  \end{equation}  \end{equation}
# Line 994  salinity ... ). Line 1098  salinity ... ).
1098    
1099  \subsection{Vector invariant form}  \subsection{Vector invariant form}
1100    
1101  For some purposes it is advantageous to write momentum advection in eq(\ref%  For some purposes it is advantageous to write momentum advection in eq(\ref
1102  {hor-mtm}) and (\ref{vertmtm}) in the (so-called) `vector invariant' form:  {eq:horizontal_mtm}) and (\ref{eq:vertical_mtm}) in the (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.
1122    
1123  % $Header$  % $Header$
1124  % $Name$  % $Name$
# Line 1028  coordinates} Line 1132  coordinates}
1132    
1133  The hydrostatic primitive equations (HPEs) in p-coordinates are:  The hydrostatic primitive equations (HPEs) in p-coordinates are:
1134  \begin{eqnarray}  \begin{eqnarray}
1135  \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}}
1136  _{h}+\mathbf{\nabla }_{p}\phi  &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\mathbf{\nabla }_{p}\phi &=&\vec{\mathbf{\mathcal{F}}}
1137  \label{eq:atmos-mom} \\  \label{eq:atmos-mom} \\
1138  \frac{\partial \phi }{\partial p}+\alpha  &=&0  \label{eq-p-hydro-start} \\  \frac{\partial \phi }{\partial p}+\alpha &=&0  \label{eq-p-hydro-start} \\
1139  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{%  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1140  \partial p} &=&0  \label{eq:atmos-cont} \\  \partial p} &=&0  \label{eq:atmos-cont} \\
1141  p\alpha  &=&RT  \label{eq:atmos-eos} \\  p\alpha &=&RT  \label{eq:atmos-eos} \\
1142  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}
1143  \end{eqnarray}%  \end{eqnarray}
1144  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
1145  surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot  surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot
1146  \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total  \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total
1147  derivative, $f=2\Omega \sin lat$ is the Coriolis parameter, $\phi =gz$ is  derivative, $f=2\Omega \sin \varphi$ is the Coriolis parameter, $\phi =gz$ is
1148  the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp%  the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp
1149  }{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref%  }{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref
1150  {eq:atmos-heat}) is the first law of thermodynamics where internal energy $%  {eq:atmos-heat}) is the first law of thermodynamics where internal energy $
1151  e=c_{v}T$, $T$ is temperature, $Q$ is the rate of heating per unit mass and $%  e=c_{v}T$, $T$ is temperature, $Q$ is the rate of heating per unit mass and $
1152  p\frac{D\alpha }{Dt}$ is the work done by the fluid in compressing.  p\frac{D\alpha }{Dt}$ is the work done by the fluid in compressing.
1153    
1154  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
# Line 1052  $\theta $ so that it looks more like a g Line 1156  $\theta $ so that it looks more like a g
1156  Differentiating (\ref{eq:atmos-eos}) we get:  Differentiating (\ref{eq:atmos-eos}) we get:
1157  \begin{equation*}  \begin{equation*}
1158  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}
1159  \end{equation*}%  \end{equation*}
1160  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 $
1161  c_{p}=c_{v}+R$, gives:  c_{p}=c_{v}+R$, gives:
1162  \begin{equation}  \begin{equation}
1163  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}
1164  \label{eq-p-heat-interim}  \label{eq-p-heat-interim}
1165  \end{equation}%  \end{equation}
1166  Potential temperature is defined:  Potential temperature is defined:
1167  \begin{equation}  \begin{equation}
1168  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}
1169  \end{equation}%  \end{equation}
1170  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
1171  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:
1172  \begin{equation}  \begin{equation}
1173  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}
1174  \end{equation}%  \end{equation}
1175  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
1176  the Exner function:  the Exner function:
1177  \begin{equation*}  \begin{equation*}
1178  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
1179  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{%  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{
1180  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}%  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}
1181  \frac{Dp}{Dt}  \frac{Dp}{Dt}
1182  \end{equation*}%  \end{equation*}
1183  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.
1184    
1185  The heat equation is obtained by noting that  The heat equation is obtained by noting that
1186  \begin{equation*}  \begin{equation*}
1187  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
1188  \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}
1189  \end{equation*}  \end{equation*}
1190  and on substituting into (\ref{eq-p-heat-interim}) gives:  and on substituting into (\ref{eq-p-heat-interim}) gives:
1191  \begin{equation}  \begin{equation}
# Line 1090  and on substituting into (\ref{eq-p-heat Line 1194  and on substituting into (\ref{eq-p-heat
1194  \end{equation}  \end{equation}
1195  which is in conservative form.  which is in conservative form.
1196    
1197  For convenience in the model we prefer to step forward (\ref%  For convenience in the model we prefer to step forward (\ref
1198  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).
1199    
1200  \subsubsection{Boundary conditions}  \subsubsection{Boundary conditions}
# Line 1134  _{o}(p_{o})=g~Z_{topo}$, defined: Line 1238  _{o}(p_{o})=g~Z_{topo}$, defined:
1238    
1239  The final form of the HPE's in p coordinates is then:  The final form of the HPE's in p coordinates is then:
1240  \begin{eqnarray}  \begin{eqnarray}
1241  \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}}
1242  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \label{eq:atmos-prime} \\
1243  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\
1244  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{%  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1245  \partial p} &=&0 \\  \partial p} &=&0 \\
1246  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\
1247  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }  \label{eq:atmos-prime}  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }
1248  \end{eqnarray}  \end{eqnarray}
1249    
1250  % $Header$  % $Header$
# Line 1154  We review here the method by which the s Line 1258  We review here the method by which the s
1258  HPE's for the ocean written in z-coordinates are obtained. The  HPE's for the ocean written in z-coordinates are obtained. The
1259  non-Boussinesq equations for oceanic motion are:  non-Boussinesq equations for oceanic motion are:
1260  \begin{eqnarray}  \begin{eqnarray}
1261  \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}}
1262  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\
1263  \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}
1264  &=&\epsilon _{nh}\mathcal{F}_{w} \\  &=&\epsilon _{nh}\mathcal{F}_{w} \\
1265  \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}}
1266  _{h}+\frac{\partial w}{\partial z} &=&0 \\  _{h}+\frac{\partial w}{\partial z} &=&0 \label{eq-zns-cont}\\
1267  \rho  &=&\rho (\theta ,S,p) \\  \rho &=&\rho (\theta ,S,p) \label{eq-zns-eos}\\
1268  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-zns-heat}\\
1269  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:non-boussinesq}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zns-salt}
1270  \end{eqnarray}%  \label{eq:non-boussinesq}
1271    \end{eqnarray}
1272  These equations permit acoustics modes, inertia-gravity waves,  These equations permit acoustics modes, inertia-gravity waves,
1273  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermo-haline  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermohaline
1274  mode. As written, they cannot be integrated forward consistently - if we  mode. As written, they cannot be integrated forward consistently - if we
1275  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
1276  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref%  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref
1277  {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
1278  therefore necessary to manipulate the system as follows. Differentiating the  therefore necessary to manipulate the system as follows. Differentiating the
1279  EOS (equation of state) gives:  EOS (equation of state) gives:
# Line 1181  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexp Line 1286  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexp
1286  \end{equation}  \end{equation}
1287    
1288  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 the
1289  reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref%  reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref{eq-zns-cont} gives:
 {eq-zns-cont} gives:  
1290  \begin{equation}  \begin{equation}
1291  \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{
1292  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}
1293  \end{equation}  \end{equation}
1294  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 1296  adiabatic motion, dropping the $\frac{D\
1296  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
1297  can be explicitly integrated forward:  can be explicitly integrated forward:
1298  \begin{eqnarray}  \begin{eqnarray}
1299  \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}}
1300  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}
1301  \label{eq-cns-hmom} \\  \label{eq-cns-hmom} \\
1302  \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}
1303  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\
1304  \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{
1305  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\
1306  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\
1307  \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 1315  wherever it appears in a product (ie. no
1315  `Boussinesq assumption'. The only term that then retains the full variation  `Boussinesq assumption'. The only term that then retains the full variation
1316  in $\rho $ is the gravitational acceleration:  in $\rho $ is the gravitational acceleration:
1317  \begin{eqnarray}  \begin{eqnarray}
1318  \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}}
1319  _{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}}}
1320  \label{eq-zcb-hmom} \\  \label{eq-zcb-hmom} \\
1321  \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}}
1322  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1323  \label{eq-zcb-hydro} \\  \label{eq-zcb-hydro} \\
1324  \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{
1325  \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} \\
1326  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\
1327  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\
1328  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}
1329  \end{eqnarray}  \end{eqnarray}
1330  These equations still retain acoustic modes. But, because the  These equations still retain acoustic modes. But, because the
1331  ``compressible'' terms are linearized, the pressure equation \ref%  ``compressible'' terms are linearized, the pressure equation \ref
1332  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent
1333  term appears as a Helmholtz term in the non-hydrostatic pressure equation).  term appears as a Helmholtz term in the non-hydrostatic pressure equation).
1334  These are the \emph{truly} compressible Boussinesq equations. Note that the  These are the \emph{truly} compressible Boussinesq equations. Note that the
1335  EOS must have the same pressure dependency as the linearized pressure term,  EOS must have the same pressure dependency as the linearized pressure term,
1336  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{%  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{
1337  c_{s}^{2}}$, for consistency.  c_{s}^{2}}$, for consistency.
1338    
1339  \subsubsection{`Anelastic' z-coordinate equations}  \subsubsection{`Anelastic' z-coordinate equations}
1340    
1341  The anelastic approximation filters the acoustic mode by removing the  The anelastic approximation filters the acoustic mode by removing the
1342  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}%  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}
1343  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}%  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}
1344  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between
1345  continuity and EOS. A better solution is to change the dependency on  continuity and EOS. A better solution is to change the dependency on
1346  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
1347  height and a perturbation:  height and a perturbation:
1348  \begin{equation*}  \begin{equation*}
1349  \rho =\rho (\theta ,S,p_{o}(z)+\epsilon _{s}p^{\prime })  \rho =\rho (\theta ,S,p_{o}(z)+\epsilon _{s}p^{\prime })
1350  \end{equation*}  \end{equation*}
1351  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from
1352  differentiating the EOS, the continuity equation then becomes:  differentiating the EOS, the continuity equation then becomes:
1353  \begin{equation*}  \begin{equation*}
1354  \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{
1355  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+%  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+
1356  \frac{\partial w}{\partial z}=0  \frac{\partial w}{\partial z}=0
1357  \end{equation*}  \end{equation*}
1358  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
1359  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},%  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},
1360  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and
1361  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{%  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{
1362  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta
1363  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon
1364  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation
1365  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
1366  anelastic continuity equation:  anelastic continuity equation:
1367  \begin{equation}  \begin{equation}
1368  \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}-
1369  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}
1370  \end{equation}  \end{equation}
1371  A slightly different route leads to the quasi-Boussinesq continuity equation  A slightly different route leads to the quasi-Boussinesq continuity equation
1372  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+%  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+
1373  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }%  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }
1374  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:
1375  \begin{equation}  \begin{equation}
1376  \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{
1377  \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}
1378  \end{equation}  \end{equation}
1379  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 1382  equation if:
1382  \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}}
1383  \end{equation}  \end{equation}
1384  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$
1385  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 $\frac{
1386  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The
1387  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are
1388  then:  then:
1389  \begin{eqnarray}  \begin{eqnarray}
1390  \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}}
1391  _{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}}}
1392  \label{eq-zab-hmom} \\  \label{eq-zab-hmom} \\
1393  \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}}
1394  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1395  \label{eq-zab-hydro} \\  \label{eq-zab-hydro} \\
1396  \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{
1397  \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} \\
1398  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\
1399  \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 1406  Here, the objective is to drop the depth
1406  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
1407  yield the ``truly'' incompressible Boussinesq equations:  yield the ``truly'' incompressible Boussinesq equations:
1408  \begin{eqnarray}  \begin{eqnarray}
1409  \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}}
1410  _{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}}}
1411  \label{eq-ztb-hmom} \\  \label{eq-ztb-hmom} \\
1412  \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}}
1413  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1414  \label{eq-ztb-hydro} \\  \label{eq-ztb-hydro} \\
1415  \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 1428  retain compressibility effects in the de
1428  density thus:  density thus:
1429  \begin{equation*}  \begin{equation*}
1430  \rho =\rho _{o}+\rho ^{\prime }  \rho =\rho _{o}+\rho ^{\prime }
1431  \end{equation*}%  \end{equation*}
1432  We then assert that variations with depth of $\rho _{o}$ are unimportant  We then assert that variations with depth of $\rho _{o}$ are unimportant
1433  while the compressible effects in $\rho ^{\prime }$ are:  while the compressible effects in $\rho ^{\prime }$ are:
1434  \begin{equation*}  \begin{equation*}
1435  \rho _{o}=\rho _{c}  \rho _{o}=\rho _{c}
1436  \end{equation*}%  \end{equation*}
1437  \begin{equation*}  \begin{equation*}
1438  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}
1439  \end{equation*}%  \end{equation*}
1440  This then yields what we can call the semi-compressible Boussinesq  This then yields what we can call the semi-compressible Boussinesq
1441  equations:  equations:
1442  \begin{eqnarray}  \begin{eqnarray}
1443  \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}}
1444  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{%  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{
1445  \mathcal{F}}}  \label{eq:ocean-mom} \\  \mathcal{F}}}  \label{eq:ocean-mom} \\
1446  \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
1447  _{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 1452  _{c}}\frac{\partial p^{\prime }}{\partia
1452  \\  \\
1453  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\
1454  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}
1455  \end{eqnarray}%  \end{eqnarray}
1456  Note that the hydrostatic pressure of the resting fluid, including that  Note that the hydrostatic pressure of the resting fluid, including that
1457  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
1458  dynamics.  dynamics.
# Line 1372  In spherical coordinates, the velocity c Line 1476  In spherical coordinates, the velocity c
1476  and vertical direction respectively, are given by (see Fig.2) :  and vertical direction respectively, are given by (see Fig.2) :
1477    
1478  \begin{equation*}  \begin{equation*}
1479  u=r\cos \phi \frac{D\lambda }{Dt}  u=r\cos \varphi \frac{D\lambda }{Dt}
1480  \end{equation*}  \end{equation*}
1481    
1482  \begin{equation*}  \begin{equation*}
1483  v=r\frac{D\phi }{Dt}\qquad  v=r\frac{D\varphi }{Dt}\qquad
1484  \end{equation*}  \end{equation*}
1485  $\qquad \qquad \qquad \qquad $  $\qquad \qquad \qquad \qquad $
1486    
1487  \begin{equation*}  \begin{equation*}
1488  \dot{r}=\frac{Dr}{Dt}  \dot{r}=\frac{Dr}{Dt}
1489  \end{equation*}  \end{equation*}
1490    
1491  Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial  Here $\varphi $ is the latitude, $\lambda $ the longitude, $r$ the radial
1492  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
1493  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.
1494    
# Line 1392  The `grad' ($\nabla $) and `div' ($\nabl Line 1496  The `grad' ($\nabla $) and `div' ($\nabl
1496  spherical coordinates:  spherical coordinates:
1497    
1498  \begin{equation*}  \begin{equation*}
1499  \nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda }%  \nabla \equiv \left( \frac{1}{r\cos \varphi }\frac{\partial }{\partial \lambda }
1500  ,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r}%  ,\frac{1}{r}\frac{\partial }{\partial \varphi },\frac{\partial }{\partial r}
1501  \right)  \right)
1502  \end{equation*}  \end{equation*}
1503    
1504  \begin{equation*}  \begin{equation*}
1505  \nabla .v\equiv \frac{1}{r\cos \phi }\left\{ \frac{\partial u}{\partial  \nabla .v\equiv \frac{1}{r\cos \varphi }\left\{ \frac{\partial u}{\partial
1506  \lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\}  \lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\}
1507  +\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}
1508  \end{equation*}  \end{equation*}
1509    
1510  %%%% \end{document}  %tci%\end{document}

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