/[MITgcm]/manual/s_overview/text/manual.tex
ViewVC logotype

Diff of /manual/s_overview/text/manual.tex

Parent Directory Parent Directory | Revision Log Revision Log | View Revision Graph Revision Graph | View Patch Patch

revision 1.2 by cnh, Tue Oct 9 10:48:03 2001 UTC revision 1.12 by cnh, Mon Nov 19 14:33:44 2001 UTC
# Line 1  Line 1 
1  % $Header$  % $Header$
2  % $Name$  % $Name$
 %\usepackage{oldgerm}  
 % I commented the following because it introduced excessive white space  
 %\usepackage{palatcm}              % better PDF  
 % page headers and footers  
 %\pagestyle{fancy}  
 % referencing  
 %% \newcommand{\refequ}[1]{equation (\ref{equ:#1})}  
 %% \newcommand{\refequbig}[1]{Equation (\ref{equ:#1})}  
 %% \newcommand{\reftab}[1]{Tab.~\ref{tab:#1}}  
 %% \newcommand{\reftabno}[1]{\ref{tab:#1}}  
 %% \newcommand{\reffig}[1]{Fig.~\ref{fig:#1}}  
 %% \newcommand{\reffigno}[1]{\ref{fig:#1}}  
 % stuff for psfrag  
 %% \newcommand{\textinfigure}[1]{{\footnotesize\textbf{\textsf{#1}}}}  
 %% \newcommand{\mathinfigure}[1]{\small\ensuremath{{#1}}}  
 % This allows numbering of subsubsections  
 % This changes the the chapter title  
 %\renewcommand{\chaptername}{Section}  
   
   
 %%%% \documentclass[12pt]{book}  
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
 %%%% \usepackage{amsmath}  
 %%%% \usepackage{html}  
 %%%% \usepackage{epsfig}  
 %%%% \usepackage{graphics,subfigure}  
 %%%% \usepackage{array}  
 %%%% \usepackage{multirow}  
 %%%% \usepackage{fancyhdr}  
 %%%% \usepackage{psfrag}  
   
 %%%% %TCIDATA{OutputFilter=Latex.dll}  
 %%%% %TCIDATA{LastRevised=Thursday, October 04, 2001 14:41:22}  
 %%%% %TCIDATA{<META NAME="GraphicsSave" CONTENT="32">}  
 %%%% %TCIDATA{Language=American English}  
   
 %%%% \fancyhead{}  
 %%%% \fancyhead[LO]{\slshape \rightmark}  
 %%%% \fancyhead[RE]{\slshape \leftmark}  
 %%%% \fancyhead[RO,LE]{\thepage}  
 %%%% \fancyfoot[CO,CE]{\today}  
 %%%% \fancyfoot[RO,LE]{ }  
 %%%% \renewcommand{\headrulewidth}{0.4pt}  
 %%%% \renewcommand{\footrulewidth}{0.4pt}  
 %%%% \setcounter{secnumdepth}{3}  
 %%%% \input{tcilatex}  
 %%%%  
 %%%% \begin{document}  
 %%%%  
 %%%% \tableofcontents  
 %%%%  
 %%%% \pagebreak  
3    
4  %%%% \part{MIT GCM basics}  %tci%\documentclass[12pt]{book}
5    %tci%\usepackage{amsmath}
6    %tci%\usepackage{html}
7    %tci%\usepackage{epsfig}
8    %tci%\usepackage{graphics,subfigure}
9    %tci%\usepackage{array}
10    %tci%\usepackage{multirow}
11    %tci%\usepackage{fancyhdr}
12    %tci%\usepackage{psfrag}
13    
14    %tci%%TCIDATA{OutputFilter=Latex.dll}
15    %tci%%TCIDATA{LastRevised=Thursday, October 04, 2001 14:41:22}
16    %tci%%TCIDATA{<META NAME="GraphicsSave" CONTENT="32">}
17    %tci%%TCIDATA{Language=American English}
18    
19    %tci%\fancyhead{}
20    %tci%\fancyhead[LO]{\slshape \rightmark}
21    %tci%\fancyhead[RE]{\slshape \leftmark}
22    %tci%\fancyhead[RO,LE]{\thepage}
23    %tci%\fancyfoot[CO,CE]{\today}
24    %tci%\fancyfoot[RO,LE]{ }
25    %tci%\renewcommand{\headrulewidth}{0.4pt}
26    %tci%\renewcommand{\footrulewidth}{0.4pt}
27    %tci%\setcounter{secnumdepth}{3}
28    %tci%\input{tcilatex}
29    
30    %tci%\begin{document}
31    
32    %tci%\tableofcontents
33    
34    
35  % Section: Overview  % Section: Overview
36    
# Line 77  MITgcm has a number of novel aspects: Line 54  MITgcm has a number of novel aspects:
54  \begin{itemize}  \begin{itemize}
55  \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
56  hydrodynamical kernel is used to drive forward both atmospheric and oceanic  hydrodynamical kernel is used to drive forward both atmospheric and oceanic
57  models - see fig.1%  models - see fig \ref{fig:onemodel}
58  \marginpar{  
59  Fig.1 One model}\ref{fig:onemodel}  %% CNHbegin
60    \input{part1/one_model_figure}
61    %% CNHend
62    
63  \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
64  small-scale and large scale processes - see fig.2%  small-scale and large scale processes - see fig \ref{fig:all-scales}
65  \marginpar{  
66  Fig.2 All scales}\ref{fig:all-scales}  %% CNHbegin
67    \input{part1/all_scales_figure}
68    %% CNHend
69    
70  \item finite volume techniques are employed yielding an intuitive  \item finite volume techniques are employed yielding an intuitive
71  discretization and support for the treatment of irregular geometries using  discretization and support for the treatment of irregular geometries using
72  orthogonal curvilinear grids and shaved cells - see fig.3%  orthogonal curvilinear grids and shaved cells - see fig \ref{fig:finite-volumes}
73  \marginpar{  
74  Fig.3 Finite volumes}\ref{fig:Finite volumes}  %% CNHbegin
75    \input{part1/fvol_figure}
76    %% CNHend
77    
78  \item tangent linear and adjoint counterparts are automatically maintained  \item tangent linear and adjoint counterparts are automatically maintained
79  along with the forward model, permitting sensitivity and optimization  along with the forward model, permitting sensitivity and optimization
# Line 100  studies. Line 83  studies.
83  computational platforms.  computational platforms.
84  \end{itemize}  \end{itemize}
85    
86  Key publications reporting on and charting the development of the model are  Key publications reporting on and charting the development of the model are:
87  listed in an Appendix.  
88    \begin{verbatim}
89    
90    Hill, C. and J. Marshall, (1995)
91    Application of a Parallel Navier-Stokes Model to Ocean Circulation in
92    Parallel Computational Fluid Dynamics
93    In Proceedings of Parallel Computational Fluid Dynamics: Implementations
94    and Results Using Parallel Computers, 545-552.
95    Elsevier Science B.V.: New York
96    
97    Marshall, J., C. Hill, L. Perelman, and A. Adcroft, (1997)
98    Hydrostatic, quasi-hydrostatic, and nonhydrostatic ocean modeling,
99    J. Geophysical Res., 102(C3), 5733-5752.
100    
101    Marshall, J., A. Adcroft, C. Hill, L. Perelman, and C. Heisey, (1997)
102    A finite-volume, incompressible Navier Stokes model for studies of the ocean
103    on parallel computers,
104    J. Geophysical Res., 102(C3), 5753-5766.
105    
106    Adcroft, A.J., Hill, C.N. and J. Marshall, (1997)
107    Representation of topography by shaved cells in a height coordinate ocean
108    model
109    Mon Wea Rev, vol 125, 2293-2315
110    
111    Marshall, J., Jones, H. and C. Hill, (1998)
112    Efficient ocean modeling using non-hydrostatic algorithms
113    Journal of Marine Systems, 18, 115-134
114    
115    Adcroft, A., Hill C. and J. Marshall: (1999)
116    A new treatment of the Coriolis terms in C-grid models at both high and low
117    resolutions,
118    Mon. Wea. Rev. Vol 127, pages 1928-1936
119    
120    Hill, C, Adcroft,A., Jamous,D., and J. Marshall, (1999)
121    A Strategy for Terascale Climate Modeling.
122    In Proceedings of the Eight ECMWF Workshop on the Use of Parallel Processors
123    in Meteorology
124    
125    Marotzke, J, Giering,R., Zhang, K.Q., Stammer,D., Hill,C., and T.Lee, (1999)
126    Construction of the adjoint MIT ocean general circulation model and
127    application to Atlantic heat transport variability
128    J. Geophysical Res., 104(C12), 29,529-29,547.
129    
130    
131    \end{verbatim}
132    
133  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
134  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  
135    
136  % $Header$  % $Header$
137  % $Name$  % $Name$
# Line 114  give a feel for the wide range of proble Line 140  give a feel for the wide range of proble
140    
141  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,
142  from convection on the scale of meters in the ocean to the global pattern of  from convection on the scale of meters in the ocean to the global pattern of
143  atmospheric winds - see fig.2\ref{fig:all-scales}. To give a flavor of the  atmospheric winds - see figure \ref{fig:all-scales}. To give a flavor of the
144  kinds of problems the model has been used to study, we briefly describe some  kinds of problems the model has been used to study, we briefly describe some
145  of them here. A more detailed description of the underlying formulation,  of them here. A more detailed description of the underlying formulation,
146  numerical algorithm and implementation that lie behind these calculations is  numerical algorithm and implementation that lie behind these calculations is
147  given later. Indeed many of the illustrative examples shown below can be  given later. Indeed many of the illustrative examples shown below can be
148  easily reproduced: simply download the model (the minimum you need is a PC  easily reproduced: simply download the model (the minimum you need is a PC
149  running linux, together with a FORTRAN\ 77 compiler) and follow the examples  running Linux, together with a FORTRAN\ 77 compiler) and follow the examples
150  described in detail in the documentation.  described in detail in the documentation.
151    
152  \subsection{Global atmosphere: `Held-Suarez' benchmark}  \subsection{Global atmosphere: `Held-Suarez' benchmark}
153    
154  A novel feature of MITgcm is its ability to simulate both atmospheric and  A novel feature of MITgcm is its ability to simulate, using one basic algorithm,
155  oceanographic flows at both small and large scales.  both atmospheric and oceanographic flows at both small and large scales.
156    
157  Fig.E1a.\ref{fig:Held-Suarez} shows an instantaneous plot of the 500$mb$  Figure \ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$
158  temperature field obtained using the atmospheric isomorph of MITgcm run at  temperature field obtained using the atmospheric isomorph of MITgcm run at
159  2.8$^{\circ }$ resolution on the cubed sphere. We see cold air over the pole  2.8$^{\circ }$ resolution on the cubed sphere. We see cold air over the pole
160  (blue) and warm air along an equatorial band (red). Fully developed  (blue) and warm air along an equatorial band (red). Fully developed
# Line 139  radiative-convective equilibrium profile Line 165  radiative-convective equilibrium profile
165  in Held and Suarez; 1994 designed to test atmospheric hydrodynamical cores -  in Held and Suarez; 1994 designed to test atmospheric hydrodynamical cores -
166  there are no mountains or land-sea contrast.  there are no mountains or land-sea contrast.
167    
168    %% CNHbegin
169    \input{part1/cubic_eddies_figure}
170    %% CNHend
171    
172  As described in Adcroft (2001), a `cubed sphere' is used to discretize the  As described in Adcroft (2001), a `cubed sphere' is used to discretize the
173  globe permitting a uniform gridding and obviated the need to fourier filter.  globe permitting a uniform griding and obviated the need to Fourier filter.
174  The `vector-invariant' form of MITgcm supports any orthogonal curvilinear  The `vector-invariant' form of MITgcm supports any orthogonal curvilinear
175  grid, of which the cubed sphere is just one of many choices.  grid, of which the cubed sphere is just one of many choices.
176    
177  Fig.E1b shows the 5-year mean, zonally averaged potential temperature, zonal  Figure \ref{fig:hs_zave_u} shows the 5-year mean, zonally averaged zonal
178  wind and meridional overturning streamfunction from a 20-level version of  wind from a 20-level configuration of
179  the model. It compares favorable with more conventional spatial  the model. It compares favorable with more conventional spatial
180  discretization approaches.  discretization approaches. The two plots show the field calculated using the
181    cube-sphere grid and the flow calculated using a regular, spherical polar
182  A regular spherical lat-lon grid can also be used.  latitude-longitude grid. Both grids are supported within the model.
183    
184    %% CNHbegin
185    \input{part1/hs_zave_u_figure}
186    %% CNHend
187    
188  \subsection{Ocean gyres}  \subsection{Ocean gyres}
189    
# Line 161  diffusive patterns of ocean currents. Bu Line 195  diffusive patterns of ocean currents. Bu
195  increased until the baroclinic instability process is resolved, numerical  increased until the baroclinic instability process is resolved, numerical
196  solutions of a different and much more realistic kind, can be obtained.  solutions of a different and much more realistic kind, can be obtained.
197    
198  Fig. ?.? shows the surface temperature and velocity field obtained from  Figure \ref{fig:ocean-gyres} shows the surface temperature and velocity
199  MITgcm run at $\frac{1}{6}^{\circ }$ horizontal resolution on a $lat-lon$  field obtained from MITgcm run at $\frac{1}{6}^{\circ }$ horizontal
200    resolution on a $lat-lon$
201  grid in which the pole has been rotated by 90$^{\circ }$ on to the equator  grid in which the pole has been rotated by 90$^{\circ }$ on to the equator
202  (to avoid the converging of meridian in northern latitudes). 21 vertical  (to avoid the converging of meridian in northern latitudes). 21 vertical
203  levels are used in the vertical with a `lopped cell' representation of  levels are used in the vertical with a `lopped cell' representation of
204  topography. The development and propagation of anomalously warm and cold  topography. The development and propagation of anomalously warm and cold
205  eddies can be clearly been seen in the Gulf Stream region. The transport of  eddies can be clearly seen in the Gulf Stream region. The transport of
206  warm water northward by the mean flow of the Gulf Stream is also clearly  warm water northward by the mean flow of the Gulf Stream is also clearly
207  visible.  visible.
208    
209    %% CNHbegin
210    \input{part1/atl6_figure}
211    %% CNHend
212    
213    
214  \subsection{Global ocean circulation}  \subsection{Global ocean circulation}
215    
216  Fig.E2a shows the pattern of ocean currents at the surface of a 4$^{\circ }$  Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean currents at
217    the surface of a 4$^{\circ }$
218  global ocean model run with 15 vertical levels. Lopped cells are used to  global ocean model run with 15 vertical levels. Lopped cells are used to
219  represent topography on a regular $lat-lon$ grid extending from 70$^{\circ  represent topography on a regular $lat-lon$ grid extending from 70$^{\circ
220  }N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with  }N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with
# Line 181  mixed boundary conditions on temperature Line 222  mixed boundary conditions on temperature
222  transfer properties of ocean eddies, convection and mixing is parameterized  transfer properties of ocean eddies, convection and mixing is parameterized
223  in this model.  in this model.
224    
225  Fig.E2b shows the meridional overturning circulation of the global ocean in  Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning
226  Sverdrups.  circulation of the global ocean in Sverdrups.
227    
228    %%CNHbegin
229    \input{part1/global_circ_figure}
230    %%CNHend
231    
232  \subsection{Convection and mixing over topography}  \subsection{Convection and mixing over topography}
233    
# Line 190  Dense plumes generated by localized cool Line 235  Dense plumes generated by localized cool
235  ocean may be influenced by rotation when the deformation radius is smaller  ocean may be influenced by rotation when the deformation radius is smaller
236  than the width of the cooling region. Rather than gravity plumes, the  than the width of the cooling region. Rather than gravity plumes, the
237  mechanism for moving dense fluid down the shelf is then through geostrophic  mechanism for moving dense fluid down the shelf is then through geostrophic
238  eddies. The simulation shown in the figure (blue is cold dense fluid, red is  eddies. The simulation shown in the figure \ref{fig:convect-and-topo}
239    (blue is cold dense fluid, red is
240  warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to  warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to
241  trigger convection by surface cooling. The cold, dense water falls down the  trigger convection by surface cooling. The cold, dense water falls down the
242  slope but is deflected along the slope by rotation. It is found that  slope but is deflected along the slope by rotation. It is found that
# Line 198  entrainment in the vertical plane is red Line 244  entrainment in the vertical plane is red
244  strong, and replaced by lateral entrainment due to the baroclinic  strong, and replaced by lateral entrainment due to the baroclinic
245  instability of the along-slope current.  instability of the along-slope current.
246    
247    %%CNHbegin
248    \input{part1/convect_and_topo}
249    %%CNHend
250    
251  \subsection{Boundary forced internal waves}  \subsection{Boundary forced internal waves}
252    
253  The unique ability of MITgcm to treat non-hydrostatic dynamics in the  The unique ability of MITgcm to treat non-hydrostatic dynamics in the
# Line 205  presence of complex geometry makes it an Line 255  presence of complex geometry makes it an
255  dynamics and mixing in oceanic canyons and ridges driven by large amplitude  dynamics and mixing in oceanic canyons and ridges driven by large amplitude
256  barotropic tidal currents imposed through open boundary conditions.  barotropic tidal currents imposed through open boundary conditions.
257    
258  Fig. ?.? shows the influence of cross-slope topographic variations on  Fig. \ref{fig:boundary-forced-wave} shows the influence of cross-slope
259    topographic variations on
260  internal wave breaking - the cross-slope velocity is in color, the density  internal wave breaking - the cross-slope velocity is in color, the density
261  contoured. The internal waves are excited by application of open boundary  contoured. The internal waves are excited by application of open boundary
262  conditions on the left.\ They propagate to the sloping boundary (represented  conditions on the left. They propagate to the sloping boundary (represented
263  using MITgcm's finite volume spatial discretization) where they break under  using MITgcm's finite volume spatial discretization) where they break under
264  nonhydrostatic dynamics.  nonhydrostatic dynamics.
265    
266    %%CNHbegin
267    \input{part1/boundary_forced_waves}
268    %%CNHend
269    
270  \subsection{Parameter sensitivity using the adjoint of MITgcm}  \subsection{Parameter sensitivity using the adjoint of MITgcm}
271    
272  Forward and tangent linear counterparts of MITgcm are supported using an  Forward and tangent linear counterparts of MITgcm are supported using an
273  `automatic adjoint compiler'. These can be used in parameter sensitivity and  `automatic adjoint compiler'. These can be used in parameter sensitivity and
274  data assimilation studies.  data assimilation studies.
275    
276  As one example of application of the MITgcm adjoint, Fig.E4 maps the  As one example of application of the MITgcm adjoint, Figure \ref{fig:hf-sensitivity}
277  gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude  maps the gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude
278  of the overturning streamfunction shown in fig?.? at 40$^{\circ }$N and $%  of the overturning stream-function shown in figure \ref{fig:large-scale-circ}
279  \mathcal{H}$ is the air-sea heat flux 100 years before. We see that $J$ is  at 60$^{\circ }$N and $
280    \mathcal{H}(\lambda,\varphi)$ is the mean, local air-sea heat flux over
281    a 100 year period. We see that $J$ is
282  sensitive to heat fluxes over the Labrador Sea, one of the important sources  sensitive to heat fluxes over the Labrador Sea, one of the important sources
283  of deep water for the thermohaline circulations. This calculation also  of deep water for the thermohaline circulations. This calculation also
284  yields sensitivities to all other model parameters.  yields sensitivities to all other model parameters.
285    
286    %%CNHbegin
287    \input{part1/adj_hf_ocean_figure}
288    %%CNHend
289    
290  \subsection{Global state estimation of the ocean}  \subsection{Global state estimation of the ocean}
291    
292  An important application of MITgcm is in state estimation of the global  An important application of MITgcm is in state estimation of the global
293  ocean circulation. An appropriately defined `cost function', which measures  ocean circulation. An appropriately defined `cost function', which measures
294  the departure of the model from observations (both remotely sensed and  the departure of the model from observations (both remotely sensed and
295  insitu) over an interval of time, is minimized by adjusting `control  in-situ) over an interval of time, is minimized by adjusting `control
296  parameters' such as air-sea fluxes, the wind field, the initial conditions  parameters' such as air-sea fluxes, the wind field, the initial conditions
297  etc. Figure ?.? shows an estimate of the time-mean surface elevation of the  etc. Figure \ref{fig:assimilated-globes} shows an estimate of the time-mean
298  ocean obtained by bringing the model in to consistency with altimetric and  surface elevation of the ocean obtained by bringing the model in to
299  in-situ observations over the period 1992-1997.  consistency with altimetric and in-situ observations over the period
300    1992-1997. {\bf CHANGE THIS TEXT - FIG FROM PATRICK/CARL/DETLEF}
301    
302    %% CNHbegin
303    \input{part1/globes_figure}
304    %% CNHend
305    
306  \subsection{Ocean biogeochemical cycles}  \subsection{Ocean biogeochemical cycles}
307    
308  MITgcm is being used to study global biogeochemical cycles in the ocean. For  MITgcm is being used to study global biogeochemical cycles in the ocean. For
309  example one can study the effects of interannual changes in meteorological  example one can study the effects of interannual changes in meteorological
310  forcing and upper ocean circulation on the fluxes of carbon dioxide and  forcing and upper ocean circulation on the fluxes of carbon dioxide and
311  oxygen between the ocean and atmosphere. The figure shows the annual air-sea  oxygen between the ocean and atmosphere. Figure \ref{fig:biogeo} shows
312  flux of oxygen and its relation to density outcrops in the southern oceans  the annual air-sea flux of oxygen and its relation to density outcrops in
313  from a single year of a global, interannually varying simulation.  the southern oceans from a single year of a global, interannually varying
314    simulation. The simulation is run at $1^{\circ}\times1^{\circ}$ resolution
315  Chris - get figure here: http://puddle.mit.edu/\symbol{126}%  telescoping to $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not shown).
316  mick/biogeochem.html  
317    %%CNHbegin
318    \input{part1/biogeo_figure}
319    %%CNHend
320    
321  \subsection{Simulations of laboratory experiments}  \subsection{Simulations of laboratory experiments}
322    
323  Figure ?.? shows MITgcm being used to simulate a laboratory experiment  Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a
324  enquiring in to the dynamics of the Antarctic Circumpolar Current (ACC). An  laboratory experiment inquiring in to the dynamics of the Antarctic Circumpolar Current (ACC). An
325  initially homogeneous tank of water ($1m$ in diameter) is driven from its  initially homogeneous tank of water ($1m$ in diameter) is driven from its
326  free surface by a rotating heated disk. The combined action of mechanical  free surface by a rotating heated disk. The combined action of mechanical
327  and thermal forcing creates a lens of fluid which becomes baroclinically  and thermal forcing creates a lens of fluid which becomes baroclinically
328  unstable. The stratification and depth of penetration of the lens is  unstable. The stratification and depth of penetration of the lens is
329  arrested by its instability in a process analogous to that whic sets the  arrested by its instability in a process analogous to that which sets the
330  stratification of the ACC.  stratification of the ACC.
331    
332    %%CNHbegin
333    \input{part1/lab_figure}
334    %%CNHend
335    
336  % $Header$  % $Header$
337  % $Name$  % $Name$
338    
# Line 267  stratification of the ACC. Line 340  stratification of the ACC.
340    
341  To render atmosphere and ocean models from one dynamical core we exploit  To render atmosphere and ocean models from one dynamical core we exploit
342  `isomorphisms' between equation sets that govern the evolution of the  `isomorphisms' between equation sets that govern the evolution of the
343  respective fluids - see fig.4%  respective fluids - see figure \ref{fig:isomorphic-equations}.
344  \marginpar{  One system of hydrodynamical equations is written down
 Fig.4. Isomorphisms}. One system of hydrodynamical equations is written down  
345  and encoded. The model variables have different interpretations depending on  and encoded. The model variables have different interpretations depending on
346  whether the atmosphere or ocean is being studied. Thus, for example, the  whether the atmosphere or ocean is being studied. Thus, for example, the
347  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are
348  modeling the atmosphere and height, $z$, if we are modeling the ocean.  modeling the atmosphere (left hand side of figure \ref{fig:isomorphic-equations})
349    and height, $z$, if we are modeling the ocean (right hand side of figure
350    \ref{fig:isomorphic-equations}).
351    
352    %%CNHbegin
353    \input{part1/zandpcoord_figure.tex}
354    %%CNHend
355    
356  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
357  velocity $\vec{\mathbf{v}}$, active tracers $\theta $ and $S$, a  velocity $\vec{\mathbf{v}}$, active tracers $\theta $ and $S$, a
# Line 281  velocity $\vec{\mathbf{v}}$, active trac Line 359  velocity $\vec{\mathbf{v}}$, active trac
359  depend on $\theta $, $S$, and $p$. The equations that govern the evolution  depend on $\theta $, $S$, and $p$. The equations that govern the evolution
360  of these fields, obtained by applying the laws of classical mechanics and  of these fields, obtained by applying the laws of classical mechanics and
361  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of
362  a generic vertical coordinate, $r$, see fig.5%  a generic vertical coordinate, $r$, so that the appropriate
363  \marginpar{  kinematic boundary conditions can be applied isomorphically
364  Fig.5 The vertical coordinate of model}:  see figure \ref{fig:zandp-vert-coord}.
365    
366    %%CNHbegin
367    \input{part1/vertcoord_figure.tex}
368    %%CNHend
369    
370  \begin{equation*}  \begin{equation*}
371  \frac{D\vec{\mathbf{v}_{h}}}{Dt}+\left( 2\vec{\Omega}\times \vec{\mathbf{v}}%  \frac{D\vec{\mathbf{v}_{h}}}{Dt}+\left( 2\vec{\Omega}\times \vec{\mathbf{v}}
372  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}%  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}
373  \text{ horizontal mtm}  \text{ horizontal mtm} \label{eq:horizontal_mtm}
374  \end{equation*}  \end{equation*}
375    
376  \begin{equation*}  \begin{equation}
377  \frac{D\dot{r}}{Dt}+\widehat{k}\cdot \left( 2\vec{\Omega}\times \vec{\mathbf{%  \frac{D\dot{r}}{Dt}+\widehat{k}\cdot \left( 2\vec{\Omega}\times \vec{\mathbf{
378  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{
379  vertical mtm}  vertical mtm} \label{eq:vertical_mtm}
380  \end{equation*}  \end{equation}
381    
382  \begin{equation}  \begin{equation}
383  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{%  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{
384  \partial r}=0\text{ continuity}  \label{eq:continuous}  \partial r}=0\text{ continuity}  \label{eq:continuity}
385  \end{equation}  \end{equation}
386    
387  \begin{equation*}  \begin{equation}
388  b=b(\theta ,S,r)\text{ equation of state}  b=b(\theta ,S,r)\text{ equation of state} \label{eq:equation_of_state}
389  \end{equation*}  \end{equation}
390    
391  \begin{equation*}  \begin{equation}
392  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature}  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature}
393  \end{equation*}  \label{eq:potential_temperature}
394    \end{equation}
395    
396  \begin{equation*}  \begin{equation}
397  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity}  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity}
398  \end{equation*}  \label{eq:humidity_salt}
399    \end{equation}
400    
401  Here:  Here:
402    
# Line 326  is the total derivative} Line 410  is the total derivative}
410  \end{equation*}  \end{equation*}
411    
412  \begin{equation*}  \begin{equation*}
413  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}%  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}
414  \text{ is the `grad' operator}  \text{ is the `grad' operator}
415  \end{equation*}  \end{equation*}
416  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}%  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}
417  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$
418  is a unit vector in the vertical  is a unit vector in the vertical
419    
# Line 363  S\text{ is specific humidity in the atmo Line 447  S\text{ is specific humidity in the atmo
447  \end{equation*}  \end{equation*}
448    
449  \begin{equation*}  \begin{equation*}
450  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{%  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{
451  \mathbf{v}}  \mathbf{v}}
452  \end{equation*}  \end{equation*}
453    
# Line 376  S\text{ is specific humidity in the atmo Line 460  S\text{ is specific humidity in the atmo
460  \end{equation*}  \end{equation*}
461    
462  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
463  extensive `physics' packages for atmosphere and ocean described in Chapter 6.  `physics' and forcing packages for atmosphere and ocean. These are described
464    in later chapters.
465    
466  \subsection{Kinematic Boundary conditions}  \subsection{Kinematic Boundary conditions}
467    
468  \subsubsection{vertical}  \subsubsection{vertical}
469    
470  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}):
471    
472  \begin{equation}  \begin{equation}
473  \dot{r}=0atr=R_{fixed}(x,y)\text{ (ocean bottom, top of the atmosphere)}  \dot{r}=0atr=R_{fixed}(x,y)\text{ (ocean bottom, top of the atmosphere)}
# Line 391  at fixed and moving $r$ surfaces we set Line 476  at fixed and moving $r$ surfaces we set
476    
477  \begin{equation}  \begin{equation}
478  \dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \  \dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \
479  (oceansurface,bottomoftheatmosphere)}  \label{eq:movingbc}  (ocean surface,bottom of the atmosphere)}  \label{eq:movingbc}
480  \end{equation}  \end{equation}
481    
482  Here  Here
# Line 408  of motion. Line 493  of motion.
493    
494  \begin{equation}  \begin{equation}
495  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}
496  \end{equation}%  \end{equation}
497  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.
498    
499  \subsection{Atmosphere}  \subsection{Atmosphere}
500    
501  In the atmosphere, see fig.5, we interpret:  In the atmosphere, (see figure \ref{fig:zandp-vert-coord}), we interpret:
502    
503  \begin{equation}  \begin{equation}
504  r=p\text{ is the pressure}  \label{eq:atmos-r}  r=p\text{ is the pressure}  \label{eq:atmos-r}
# Line 445  where Line 530  where
530    
531  \begin{equation*}  \begin{equation*}
532  T\text{ is absolute temperature}  T\text{ is absolute temperature}
533  \end{equation*}%  \end{equation*}
534  \begin{equation*}  \begin{equation*}
535  p\text{ is the pressure}  p\text{ is the pressure}
536  \end{equation*}%  \end{equation*}
537  \begin{eqnarray*}  \begin{eqnarray*}
538  &&z\text{ is the height of the pressure surface} \\  &&z\text{ is the height of the pressure surface} \\
539  &&g\text{ is the acceleration due to gravity}  &&g\text{ is the acceleration due to gravity}
# Line 458  In the above the ideal gas law, $p=\rho Line 543  In the above the ideal gas law, $p=\rho
543  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)
544  \begin{equation}  \begin{equation}
545  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}
546  \end{equation}%  \end{equation}
547  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
548  constant and $c_{p}$ the specific heat of air at constant pressure.  constant and $c_{p}$ the specific heat of air at constant pressure.
549    
# Line 484  The boundary conditions at top and botto Line 569  The boundary conditions at top and botto
569  atmosphere)}  \label{eq:moving-bc-atmos}  atmosphere)}  \label{eq:moving-bc-atmos}
570  \end{eqnarray}  \end{eqnarray}
571    
572  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})
573  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 $p$
574  coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}).  coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}).
575    
576  \subsection{Ocean}  \subsection{Ocean}
# Line 508  At the bottom of the ocean: $R_{fixed}(x Line 593  At the bottom of the ocean: $R_{fixed}(x
593    
594  The surface of the ocean is given by: $R_{moving}=\eta $  The surface of the ocean is given by: $R_{moving}=\eta $
595    
596  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 $
597  R_{o}=Z_{o}=0$.  R_{o}=Z_{o}=0$.
598    
599  Boundary conditions are:  Boundary conditions are:
# Line 516  Boundary conditions are: Line 601  Boundary conditions are:
601  \begin{eqnarray}  \begin{eqnarray}
602  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}
603  \\  \\
604  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)
605  \label{eq:moving-bc-ocean}}  \label{eq:moving-bc-ocean}}
606  \end{eqnarray}  \end{eqnarray}
607  where $\eta $ is the elevation of the free surface.  where $\eta $ is the elevation of the free surface.
608    
609  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
610    of oceanic equations
611  which, for convenience, are written out in $z$ coordinates in Appendix Ocean  which, for convenience, are written out in $z$ coordinates in Appendix Ocean
612  - see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}).  - see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}).
613    
# Line 533  Let us separate $\phi $ in to surface, h Line 619  Let us separate $\phi $ in to surface, h
619  \begin{equation}  \begin{equation}
620  \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)
621  \label{eq:phi-split}  \label{eq:phi-split}
622  \end{equation}%  \end{equation}
623  and write eq(\ref{incompressible}a,b) in the form:  and write eq(\ref{eq:incompressible}) in the form:
624    
625  \begin{equation}  \begin{equation}
626  \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 547  _{nh}=\vec{\mathbf{G}}_{\vec{v}_{h}}  \l Line 633  _{nh}=\vec{\mathbf{G}}_{\vec{v}_{h}}  \l
633  \end{equation}  \end{equation}
634    
635  \begin{equation}  \begin{equation}
636  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{%  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{
637  \partial r}=G_{\dot{r}}  \label{eq:mom-w}  \partial r}=G_{\dot{r}}  \label{eq:mom-w}
638  \end{equation}  \end{equation}
639  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.
640    
641  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
642  {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
643  terms in the momentum equations. In spherical coordinates they take the form%  terms in the momentum equations. In spherical coordinates they take the form
644  \footnote{%  \footnote{
645  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms
646  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref%  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref
647  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in
648  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (%  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (
649  \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
650  discussion:  discussion:
651    
# Line 567  discussion: Line 653  discussion:
653  \left.  \left.
654  \begin{tabular}{l}  \begin{tabular}{l}
655  $G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\  $G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\
656  $-\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\} $
657  \\  \\
658  $-\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\} $
659  \\  \\
660  $+\mathcal{F}_{u}$%  $+\mathcal{F}_{u}$
661  \end{tabular}%  \end{tabular}
662  \ \right\} \left\{  \ \right\} \left\{
663  \begin{tabular}{l}  \begin{tabular}{l}
664  \textit{advection} \\  \textit{advection} \\
665  \textit{metric} \\  \textit{metric} \\
666  \textit{Coriolis} \\  \textit{Coriolis} \\
667  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
668  \end{tabular}%  \end{tabular}
669  \ \right. \qquad  \label{eq:gu-speherical}  \ \right. \qquad  \label{eq:gu-speherical}
670  \end{equation}  \end{equation}
671    
# Line 587  $+\mathcal{F}_{u}$% Line 673  $+\mathcal{F}_{u}$%
673  \left.  \left.
674  \begin{tabular}{l}  \begin{tabular}{l}
675  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\
676  $-\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\}
677  $ \\  $ \\
678  $-\left\{ -2\Omega u\sin lat\right\} $ \\  $-\left\{ -2\Omega u\sin \varphi \right\} $ \\
679  $+\mathcal{F}_{v}$%  $+\mathcal{F}_{v}$
680  \end{tabular}%  \end{tabular}
681  \ \right\} \left\{  \ \right\} \left\{
682  \begin{tabular}{l}  \begin{tabular}{l}
683  \textit{advection} \\  \textit{advection} \\
684  \textit{metric} \\  \textit{metric} \\
685  \textit{Coriolis} \\  \textit{Coriolis} \\
686  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
687  \end{tabular}%  \end{tabular}
688  \ \right. \qquad  \label{eq:gv-spherical}  \ \right. \qquad  \label{eq:gv-spherical}
689  \end{equation}%  \end{equation}
690  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
691    
692  \begin{equation}  \begin{equation}
# Line 608  $+\mathcal{F}_{v}$% Line 694  $+\mathcal{F}_{v}$%
694  \begin{tabular}{l}  \begin{tabular}{l}
695  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\
696  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\
697  ${+}\underline{{2\Omega u\cos lat}}$ \\  ${+}\underline{{2\Omega u\cos \varphi}}$ \\
698  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$%  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$
699  \end{tabular}%  \end{tabular}
700  \ \right\} \left\{  \ \right\} \left\{
701  \begin{tabular}{l}  \begin{tabular}{l}
702  \textit{advection} \\  \textit{advection} \\
703  \textit{metric} \\  \textit{metric} \\
704  \textit{Coriolis} \\  \textit{Coriolis} \\
705  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
706  \end{tabular}%  \end{tabular}
707  \ \right.  \label{eq:gw-spherical}  \ \right.  \label{eq:gw-spherical}
708  \end{equation}%  \end{equation}
709  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
710    
711  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 `$\varphi$
712  ' is latitude.  ' is latitude.
713    
714  Grad and div operators in spherical coordinates are defined in appendix  Grad and div operators in spherical coordinates are defined in appendix
715  OPERATORS.%  OPERATORS.
716  \marginpar{  
717  Fig.6 Spherical polar coordinate system.}  %%CNHbegin
718    \input{part1/sphere_coord_figure.tex}
719    %%CNHend
720    
721  \subsubsection{Shallow atmosphere approximation}  \subsubsection{Shallow atmosphere approximation}
722    
# Line 638  hydrostatic balance and the `traditional Line 726  hydrostatic balance and the `traditional
726  Coriolis force is treated approximately and the shallow atmosphere  Coriolis force is treated approximately and the shallow atmosphere
727  approximation is made.\ The MITgcm need not make the `traditional  approximation is made.\ The MITgcm need not make the `traditional
728  approximation'. To be able to support consistent non-hydrostatic forms the  approximation'. To be able to support consistent non-hydrostatic forms the
729  shallow atmosphere approximation can be relaxed - when dividing through by $%  shallow atmosphere approximation can be relaxed - when dividing through by $
730  r $ 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 $a$,
731  the radius of the earth.  the radius of the earth.
732    
733  \subsubsection{Hydrostatic and quasi-hydrostatic forms}  \subsubsection{Hydrostatic and quasi-hydrostatic forms}
734    \label{sec:hydrostatic_and_quasi-hydrostatic_forms}
735    
736  These are discussed at length in Marshall et al (1997a).  These are discussed at length in Marshall et al (1997a).
737    
# Line 651  terms in Eqs. (\ref{eq:gu-speherical} $\ Line 740  terms in Eqs. (\ref{eq:gu-speherical} $\
740  are neglected and `${r}$' is replaced by `$a$', the mean radius of the  are neglected and `${r}$' is replaced by `$a$', the mean radius of the
741  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
742  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
743  computed at all other levels by integration of the hydrostatic relation, eq(%  computed at all other levels by integration of the hydrostatic relation, eq(
744  \ref{eq:hydrostatic}).  \ref{eq:hydrostatic}).
745    
746  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between
747  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
748  \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
749  contribution to the pressure field: only the terms underlined twice in Eqs. (%  contribution to the pressure field: only the terms underlined twice in Eqs. (
750  \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
751  and, simultaneously, the shallow atmosphere approximation is relaxed. In  and, simultaneously, the shallow atmosphere approximation is relaxed. In
752  \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 665  variation of the radial position of a pa Line 754  variation of the radial position of a pa
754  vertical momentum equation (\ref{eq:mom-w}) becomes:  vertical momentum equation (\ref{eq:mom-w}) becomes:
755    
756  \begin{equation*}  \begin{equation*}
757  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos \varphi
758  \end{equation*}  \end{equation*}
759  making a small correction to the hydrostatic pressure.  making a small correction to the hydrostatic pressure.
760    
# Line 681  only a quasi-non-hydrostatic atmospheric Line 770  only a quasi-non-hydrostatic atmospheric
770    
771  \paragraph{Non-hydrostatic Ocean}  \paragraph{Non-hydrostatic Ocean}
772    
773  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref%  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref
774  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A
775  three dimensional elliptic equation must be solved subject to Neumann  three dimensional elliptic equation must be solved subject to Neumann
776  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
777  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
778  incompressible condition eq(\ref{eq:continuous})c has already filtered out  incompressible condition eq(\ref{eq:continuity}) has already filtered out
779  acoustic modes. It does, however, ensure that the gravity waves are treated  acoustic modes. It does, however, ensure that the gravity waves are treated
780  accurately with an exact dispersion relation. The \textbf{NH} set has a  accurately with an exact dispersion relation. The \textbf{NH} set has a
781  complete angular momentum principle and consistent energetics - see White  complete angular momentum principle and consistent energetics - see White
# Line 694  and Bromley, 1995; Marshall et.al.\ 1997 Line 783  and Bromley, 1995; Marshall et.al.\ 1997
783    
784  \paragraph{Quasi-nonhydrostatic Atmosphere}  \paragraph{Quasi-nonhydrostatic Atmosphere}
785    
786  In the non-hydrostatic version of our atmospheric model we approximate $\dot{%  In the non-hydrostatic version of our atmospheric model we approximate $\dot{
787  r}$ 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})
788  (but only here) by:  (but only here) by:
789    
790  \begin{equation}  \begin{equation}
791  \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}
792  \end{equation}%  \end{equation}
793  where $p_{hy}$ is the hydrostatic pressure.  where $p_{hy}$ is the hydrostatic pressure.
794    
795  \subsubsection{Summary of equation sets supported by model}  \subsubsection{Summary of equation sets supported by model}
# Line 728  equations in $z-$coordinates are support Line 817  equations in $z-$coordinates are support
817    
818  \subparagraph{Non-hydrostatic}  \subparagraph{Non-hydrostatic}
819    
820  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$%  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$
821  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref%  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref
822  {eq:ocean-salt}).  {eq:ocean-salt}).
823    
824  \subsection{Solution strategy}  \subsection{Solution strategy}
825    
826  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{
827  NH} models is summarized in Fig.7.%  NH} models is summarized in Figure \ref{fig:solution-strategy}.
828  \marginpar{  Under all dynamics, a 2-d elliptic equation is
 Fig.7 Solution strategy} Under all dynamics, a 2-d elliptic equation is  
829  first solved to find the surface pressure and the hydrostatic pressure at  first solved to find the surface pressure and the hydrostatic pressure at
830  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
831  \textbf{QH} dynamics, the horizontal momentum equations are then stepped  \textbf{QH} dynamics, the horizontal momentum equations are then stepped
# Line 746  forward and $\dot{r}$ found from continu Line 834  forward and $\dot{r}$ found from continu
834  stepping forward the horizontal momentum equations; $\dot{r}$ is found by  stepping forward the horizontal momentum equations; $\dot{r}$ is found by
835  stepping forward the vertical momentum equation.  stepping forward the vertical momentum equation.
836    
837    %%CNHbegin
838    \input{part1/solution_strategy_figure.tex}
839    %%CNHend
840    
841  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
842  course, some complication that goes with the inclusion of $\cos \phi \ $%  course, some complication that goes with the inclusion of $\cos \varphi \ $
843  Coriolis terms and the relaxation of the shallow atmosphere approximation.  Coriolis terms and the relaxation of the shallow atmosphere approximation.
844  But this leads to negligible increase in computation. In \textbf{NH}, in  But this leads to negligible increase in computation. In \textbf{NH}, in
845  contrast, one additional elliptic equation - a three-dimensional one - must  contrast, one additional elliptic equation - a three-dimensional one - must
# Line 757  Marshall et al, 1997) resulting in a non Line 849  Marshall et al, 1997) resulting in a non
849  hydrostatic limit, is as computationally economic as the \textbf{HPEs}.  hydrostatic limit, is as computationally economic as the \textbf{HPEs}.
850    
851  \subsection{Finding the pressure field}  \subsection{Finding the pressure field}
852    \label{sec:finding_the_pressure_field}
853    
854  Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the  Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the
855  pressure field must be obtained diagnostically. We proceed, as before, by  pressure field must be obtained diagnostically. We proceed, as before, by
# Line 771  Hydrostatic pressure is obtained by inte Line 864  Hydrostatic pressure is obtained by inte
864  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:
865    
866  \begin{equation*}  \begin{equation*}
867  \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}
868  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr
869  \end{equation*}  \end{equation*}
870  and so  and so
# Line 789  atmospheric pressure pushing down on the Line 882  atmospheric pressure pushing down on the
882    
883  \subsubsection{Surface pressure}  \subsubsection{Surface pressure}
884    
885  The surface pressure equation can be obtained by integrating continuity, (%  The surface pressure equation can be obtained by integrating continuity,
886  \ref{eq:continuous})c, vertically from $r=R_{fixed}$ to $r=R_{moving}$  (\ref{eq:continuity}), vertically from $r=R_{fixed}$ to $r=R_{moving}$
887    
888  \begin{equation*}  \begin{equation*}
889  \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}
890  }_{h}+\partial _{r}\dot{r}\right) dr=0  }_{h}+\partial _{r}\dot{r}\right) dr=0
891  \end{equation*}  \end{equation*}
892    
# Line 801  Thus: Line 894  Thus:
894    
895  \begin{equation*}  \begin{equation*}
896  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta
897  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}%  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}
898  _{h}dr=0  _{h}dr=0
899  \end{equation*}  \end{equation*}
900  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 $
901  r $. The above can be rearranged to yield, using Leibnitz's theorem:  r $. The above can be rearranged to yield, using Leibnitz's theorem:
902    
903  \begin{equation}  \begin{equation}
904  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot
905  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}
906  \label{eq:free-surface}  \label{eq:free-surface}
907  \end{equation}%  \end{equation}
908  where we have incorporated a source term.  where we have incorporated a source term.
909    
910  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential
911  (atmospheric model), in (\ref{mtm-split}), the horizontal gradient term can  (atmospheric model), in (\ref{eq:mom-h}), the horizontal gradient term can
912  be written  be written
913  \begin{equation}  \begin{equation}
914  \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)
915  \label{eq:phi-surf}  \label{eq:phi-surf}
916  \end{equation}%  \end{equation}
917  where $b_{s}$ is the buoyancy at the surface.  where $b_{s}$ is the buoyancy at the surface.
918    
919  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
920  {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
921  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free
922  surface' and `rigid lid' approaches are available.  surface' and `rigid lid' approaches are available.
923    
924  \subsubsection{Non-hydrostatic pressure}  \subsubsection{Non-hydrostatic pressure}
925    
926  Taking the horizontal divergence of (\ref{hor-mtm}) and adding $\frac{%  Taking the horizontal divergence of (\ref{eq:mom-h}) and adding
927  \partial }{\partial r}$ of (\ref{vertmtm}), invoking the continuity equation  $\frac{\partial }{\partial r}$ of (\ref{eq:mom-w}), invoking the continuity equation
928  (\ref{incompressible}), we deduce that:  (\ref{eq:continuity}), we deduce that:
929    
930  \begin{equation}  \begin{equation}
931  \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{
932  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .%  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .
933  \vec{\mathbf{F}}  \label{eq:3d-invert}  \vec{\mathbf{F}}  \label{eq:3d-invert}
934  \end{equation}  \end{equation}
935    
# Line 856  coasts (in the ocean) and the bottom: Line 949  coasts (in the ocean) and the bottom:
949  \end{equation}  \end{equation}
950  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
951  kinematic condition (\ref{nonormalflow}) is also applied to the vertical  kinematic condition (\ref{nonormalflow}) is also applied to the vertical
952  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 $
953  \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
954  tangential component of velocity, $v_{T}$, at all solid boundaries,  tangential component of velocity, $v_{T}$, at all solid boundaries,
955  depending on the form chosen for the dissipative terms in the momentum  depending on the form chosen for the dissipative terms in the momentum
956  equations - see below.  equations - see below.
957    
958  Eq.(\ref{nonormalflow}) implies, making use of (\ref{mtm-split}), that:  Eq.(\ref{nonormalflow}) implies, making use of (\ref{eq:mom-h}), that:
959    
960  \begin{equation}  \begin{equation}
961  \widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}}  \widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}}
# Line 873  where Line 966  where
966  \begin{equation*}  \begin{equation*}
967  \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
968  _{s}+\mathbf{\nabla }\phi _{hyd}\right)  _{s}+\mathbf{\nabla }\phi _{hyd}\right)
969  \end{equation*}%  \end{equation*}
970  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem
971  (\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
972  exploit classical 3D potential theory and, by introducing an appropriately  exploit classical 3D potential theory and, by introducing an appropriately
973  chosen $\delta $-function sheet of `source-charge', replace the  chosen $\delta $-function sheet of `source-charge', replace the
974  inhomogeneous boundary condition on pressure by a homogeneous one. The  inhomogeneous boundary condition on pressure by a homogeneous one. The
975  source term $rhs$ in (\ref{eq:3d-invert}) is the divergence of the vector $%  source term $rhs$ in (\ref{eq:3d-invert}) is the divergence of the vector $
976  \vec{\mathbf{F}}.$ By simultaneously setting $%  \vec{\mathbf{F}}.$ By simultaneously setting $
977  \begin{array}{l}  \begin{array}{l}
978  \widehat{n}.\vec{\mathbf{F}}%  \widehat{n}.\vec{\mathbf{F}}
979  \end{array}%  \end{array}
980  =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
981  self-consistent but simpler homogenized Elliptic problem is obtained:  self-consistent but simpler homogenized Elliptic problem is obtained:
982    
983  \begin{equation*}  \begin{equation*}
984  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad
985  \end{equation*}%  \end{equation*}
986  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such
987  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
988  {eq:inhom-neumann-nh}) the modified boundary condition becomes:  {eq:inhom-neumann-nh}) the modified boundary condition becomes:
989    
990  \begin{equation}  \begin{equation}
# Line 902  If the flow is `close' to hydrostatic ba Line 995  If the flow is `close' to hydrostatic ba
995  converges rapidly because $\phi _{nh}\ $is then only a small correction to  converges rapidly because $\phi _{nh}\ $is then only a small correction to
996  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).
997    
998  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})
999  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.
1000    
1001  \subsection{Forcing/dissipation}  \subsection{Forcing/dissipation}
# Line 910  does not vanish at $r=R_{moving}$, and s Line 1003  does not vanish at $r=R_{moving}$, and s
1003  \subsubsection{Forcing}  \subsubsection{Forcing}
1004    
1005  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
1006  `physics packages' described in detail in chapter ??.  `physics packages' and forcing packages. These are described later on.
1007    
1008  \subsubsection{Dissipation}  \subsubsection{Dissipation}
1009    
# Line 920  Many forms of momentum dissipation are a Line 1013  Many forms of momentum dissipation are a
1013  biharmonic frictions are commonly used:  biharmonic frictions are commonly used:
1014    
1015  \begin{equation}  \begin{equation}
1016  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}}
1017  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}
1018  \end{equation}  \end{equation}
1019  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 931  friction. These coefficients are the sam Line 1024  friction. These coefficients are the sam
1024    
1025  The mixing terms for the temperature and salinity equations have a similar  The mixing terms for the temperature and salinity equations have a similar
1026  form to that of momentum except that the diffusion tensor can be  form to that of momentum except that the diffusion tensor can be
1027  non-diagonal and have varying coefficients. $\qquad $%  non-diagonal and have varying coefficients. $\qquad $
1028  \begin{equation}  \begin{equation}
1029  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
1030  _{h}^{4}(T,S)  \label{eq:diffusion}  _{h}^{4}(T,S)  \label{eq:diffusion}
1031  \end{equation}  \end{equation}
1032  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $%  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $
1033  horizontal coefficient for biharmonic diffusion. In the simplest case where  horizontal coefficient for biharmonic diffusion. In the simplest case where
1034  the subgrid-scale fluxes of heat and salt are parameterized with constant  the subgrid-scale fluxes of heat and salt are parameterized with constant
1035  horizontal and vertical diffusion coefficients, $\underline{\underline{K}}$,  horizontal and vertical diffusion coefficients, $\underline{\underline{K}}$,
# Line 947  reduces to a diagonal matrix with consta Line 1040  reduces to a diagonal matrix with consta
1040  \begin{array}{ccc}  \begin{array}{ccc}
1041  K_{h} & 0 & 0 \\  K_{h} & 0 & 0 \\
1042  0 & K_{h} & 0 \\  0 & K_{h} & 0 \\
1043  0 & 0 & K_{v}%  0 & 0 & K_{v}
1044  \end{array}  \end{array}
1045  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}
1046  \end{equation}  \end{equation}
# Line 957  salinity ... ). Line 1050  salinity ... ).
1050    
1051  \subsection{Vector invariant form}  \subsection{Vector invariant form}
1052    
1053  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
1054  {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:
1055    
1056  \begin{equation}  \begin{equation}
1057  \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}
1058  +\left( \nabla \times \vec{\mathbf{v}}\right) \times \vec{\mathbf{v}}+\nabla %  +\left( \nabla \times \vec{\mathbf{v}}\right) \times \vec{\mathbf{v}}+\nabla
1059  \left[ \frac{1}{2}(\vec{\mathbf{v}}\cdot \vec{\mathbf{v}})\right]  \left[ \frac{1}{2}(\vec{\mathbf{v}}\cdot \vec{\mathbf{v}})\right]
1060  \label{eq:vi-identity}  \label{eq:vi-identity}
1061  \end{equation}%  \end{equation}
1062  This permits alternative numerical treatments of the non-linear terms based  This permits alternative numerical treatments of the non-linear terms based
1063  on their representation as a vorticity flux. Because gradients of coordinate  on their representation as a vorticity flux. Because gradients of coordinate
1064  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
1065  representation of the metric terms in (\ref{eq:gu-speherical}), (\ref%  representation of the metric terms in (\ref{eq:gu-speherical}), (\ref
1066  {eq:gv-spherical}) and (\ref{eq:gw-spherical}), can be avoided: information  {eq:gv-spherical}) and (\ref{eq:gw-spherical}), can be avoided: information
1067  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
1068  to discretize the model.  to discretize the model.
1069    
1070  \subsection{Adjoint}  \subsection{Adjoint}
1071    
1072  Tangent linear and adjoint counterparts of the forward model and described  Tangent linear and adjoint counterparts of the forward model are described
1073  in Chapter 5.  in Chapter 5.
1074    
1075  % $Header$  % $Header$
# Line 991  coordinates} Line 1084  coordinates}
1084    
1085  The hydrostatic primitive equations (HPEs) in p-coordinates are:  The hydrostatic primitive equations (HPEs) in p-coordinates are:
1086  \begin{eqnarray}  \begin{eqnarray}
1087  \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}}
1088  _{h}+\mathbf{\nabla }_{p}\phi &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\mathbf{\nabla }_{p}\phi &=&\vec{\mathbf{\mathcal{F}}}
1089  \label{eq:atmos-mom} \\  \label{eq:atmos-mom} \\
1090  \frac{\partial \phi }{\partial p}+\alpha &=&0  \label{eq-p-hydro-start} \\  \frac{\partial \phi }{\partial p}+\alpha &=&0  \label{eq-p-hydro-start} \\
1091  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{%  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1092  \partial p} &=&0  \label{eq:atmos-cont} \\  \partial p} &=&0  \label{eq:atmos-cont} \\
1093  p\alpha &=&RT  \label{eq:atmos-eos} \\  p\alpha &=&RT  \label{eq:atmos-eos} \\
1094  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}
1095  \end{eqnarray}%  \end{eqnarray}
1096  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
1097  surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot  surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot
1098  \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total  \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total
1099  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
1100  the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp%  the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp
1101  }{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref%  }{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref
1102  {eq:atmos-heat}) is the first law of thermodynamics where internal energy $%  {eq:atmos-heat}) is the first law of thermodynamics where internal energy $
1103  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 $
1104  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.
1105    
1106  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 1015  $\theta $ so that it looks more like a g Line 1108  $\theta $ so that it looks more like a g
1108  Differentiating (\ref{eq:atmos-eos}) we get:  Differentiating (\ref{eq:atmos-eos}) we get:
1109  \begin{equation*}  \begin{equation*}
1110  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}
1111  \end{equation*}%  \end{equation*}
1112  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 $
1113  c_{p}=c_{v}+R$, gives:  c_{p}=c_{v}+R$, gives:
1114  \begin{equation}  \begin{equation}
1115  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}
1116  \label{eq-p-heat-interim}  \label{eq-p-heat-interim}
1117  \end{equation}%  \end{equation}
1118  Potential temperature is defined:  Potential temperature is defined:
1119  \begin{equation}  \begin{equation}
1120  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}
1121  \end{equation}%  \end{equation}
1122  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
1123  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:
1124  \begin{equation}  \begin{equation}
1125  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}
1126  \end{equation}%  \end{equation}
1127  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
1128  the Exner function:  the Exner function:
1129  \begin{equation*}  \begin{equation*}
1130  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
1131  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{%  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{
1132  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}%  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}
1133  \frac{Dp}{Dt}  \frac{Dp}{Dt}
1134  \end{equation*}%  \end{equation*}
1135  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.
1136    
1137  The heat equation is obtained by noting that  The heat equation is obtained by noting that
# Line 1053  and on substituting into (\ref{eq-p-heat Line 1146  and on substituting into (\ref{eq-p-heat
1146  \end{equation}  \end{equation}
1147  which is in conservative form.  which is in conservative form.
1148    
1149  For convenience in the model we prefer to step forward (\ref%  For convenience in the model we prefer to step forward (\ref
1150  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).
1151    
1152  \subsubsection{Boundary conditions}  \subsubsection{Boundary conditions}
# Line 1097  _{o}(p_{o})=g~Z_{topo}$, defined: Line 1190  _{o}(p_{o})=g~Z_{topo}$, defined:
1190    
1191  The final form of the HPE's in p coordinates is then:  The final form of the HPE's in p coordinates is then:
1192  \begin{eqnarray}  \begin{eqnarray}
1193  \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}}
1194  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \label{eq:atmos-prime} \\
1195  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\
1196  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{%  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1197  \partial p} &=&0 \\  \partial p} &=&0 \\
1198  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\
1199  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }  \label{eq:atmos-prime}  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }
1200  \end{eqnarray}  \end{eqnarray}
1201    
1202  % $Header$  % $Header$
# Line 1117  We review here the method by which the s Line 1210  We review here the method by which the s
1210  HPE's for the ocean written in z-coordinates are obtained. The  HPE's for the ocean written in z-coordinates are obtained. The
1211  non-Boussinesq equations for oceanic motion are:  non-Boussinesq equations for oceanic motion are:
1212  \begin{eqnarray}  \begin{eqnarray}
1213  \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}}
1214  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\
1215  \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}
1216  &=&\epsilon _{nh}\mathcal{F}_{w} \\  &=&\epsilon _{nh}\mathcal{F}_{w} \\
1217  \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}}
1218  _{h}+\frac{\partial w}{\partial z} &=&0 \\  _{h}+\frac{\partial w}{\partial z} &=&0 \label{eq-zns-cont}\\
1219  \rho &=&\rho (\theta ,S,p) \\  \rho &=&\rho (\theta ,S,p) \label{eq-zns-eos}\\
1220  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-zns-heat}\\
1221  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:non-boussinesq}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zns-salt}
1222  \end{eqnarray}%  \label{eq:non-boussinesq}
1223    \end{eqnarray}
1224  These equations permit acoustics modes, inertia-gravity waves,  These equations permit acoustics modes, inertia-gravity waves,
1225  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermo-haline  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermohaline
1226  mode. As written, they cannot be integrated forward consistently - if we  mode. As written, they cannot be integrated forward consistently - if we
1227  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
1228  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref%  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref
1229  {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
1230  therefore necessary to manipulate the system as follows. Differentiating the  therefore necessary to manipulate the system as follows. Differentiating the
1231  EOS (equation of state) gives:  EOS (equation of state) gives:
# Line 1144  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexp Line 1238  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexp
1238  \end{equation}  \end{equation}
1239    
1240  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
1241  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:  
1242  \begin{equation}  \begin{equation}
1243  \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{
1244  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}
1245  \end{equation}  \end{equation}
1246  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 1155  adiabatic motion, dropping the $\frac{D\ Line 1248  adiabatic motion, dropping the $\frac{D\
1248  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
1249  can be explicitly integrated forward:  can be explicitly integrated forward:
1250  \begin{eqnarray}  \begin{eqnarray}
1251  \frac{D\vec{\mathbf{v}}_{h}}{Dt}+f\hat{\mathbf{k}}\times \vec{\mathbf{v}}%  \frac{D\vec{\mathbf{v}}_{h}}{Dt}+f\hat{\mathbf{k}}\times \vec{\mathbf{v}}
1252  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}
1253  \label{eq-cns-hmom} \\  \label{eq-cns-hmom} \\
1254  \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}
1255  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\
1256  \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{
1257  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\
1258  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\
1259  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-cns-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-cns-heat} \\
# Line 1174  wherever it appears in a product (ie. no Line 1267  wherever it appears in a product (ie. no
1267  `Boussinesq assumption'. The only term that then retains the full variation  `Boussinesq assumption'. The only term that then retains the full variation
1268  in $\rho $ is the gravitational acceleration:  in $\rho $ is the gravitational acceleration:
1269  \begin{eqnarray}  \begin{eqnarray}
1270  \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}}
1271  _{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}}}
1272  \label{eq-zcb-hmom} \\  \label{eq-zcb-hmom} \\
1273  \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}}
1274  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1275  \label{eq-zcb-hydro} \\  \label{eq-zcb-hydro} \\
1276  \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{
1277  \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} \\
1278  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\
1279  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\
1280  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}
1281  \end{eqnarray}  \end{eqnarray}
1282  These equations still retain acoustic modes. But, because the  These equations still retain acoustic modes. But, because the
1283  ``compressible'' terms are linearized, the pressure equation \ref%  ``compressible'' terms are linearized, the pressure equation \ref
1284  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent
1285  term appears as a Helmholtz term in the non-hydrostatic pressure equation).  term appears as a Helmholtz term in the non-hydrostatic pressure equation).
1286  These are the \emph{truly} compressible Boussinesq equations. Note that the  These are the \emph{truly} compressible Boussinesq equations. Note that the
1287  EOS must have the same pressure dependency as the linearized pressure term,  EOS must have the same pressure dependency as the linearized pressure term,
1288  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{%  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{
1289  c_{s}^{2}}$, for consistency.  c_{s}^{2}}$, for consistency.
1290    
1291  \subsubsection{`Anelastic' z-coordinate equations}  \subsubsection{`Anelastic' z-coordinate equations}
1292    
1293  The anelastic approximation filters the acoustic mode by removing the  The anelastic approximation filters the acoustic mode by removing the
1294  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}%  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}
1295  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}%  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}
1296  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between
1297  continuity and EOS. A better solution is to change the dependency on  continuity and EOS. A better solution is to change the dependency on
1298  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
# Line 1210  height and a perturbation: Line 1303  height and a perturbation:
1303  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from
1304  differentiating the EOS, the continuity equation then becomes:  differentiating the EOS, the continuity equation then becomes:
1305  \begin{equation*}  \begin{equation*}
1306  \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{
1307  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+%  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+
1308  \frac{\partial w}{\partial z}=0  \frac{\partial w}{\partial z}=0
1309  \end{equation*}  \end{equation*}
1310  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
1311  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},%  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},
1312  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and
1313  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{%  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{
1314  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta
1315  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon
1316  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation
1317  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
1318  anelastic continuity equation:  anelastic continuity equation:
1319  \begin{equation}  \begin{equation}
1320  \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}-
1321  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}
1322  \end{equation}  \end{equation}
1323  A slightly different route leads to the quasi-Boussinesq continuity equation  A slightly different route leads to the quasi-Boussinesq continuity equation
1324  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+%  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+
1325  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }%  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }
1326  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:
1327  \begin{equation}  \begin{equation}
1328  \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{
1329  \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}
1330  \end{equation}  \end{equation}
1331  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 1241  equation if: Line 1334  equation if:
1334  \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}}
1335  \end{equation}  \end{equation}
1336  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$
1337  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 $\frac{
1338  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The
1339  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are
1340  then:  then:
1341  \begin{eqnarray}  \begin{eqnarray}
1342  \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}}
1343  _{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}}}
1344  \label{eq-zab-hmom} \\  \label{eq-zab-hmom} \\
1345  \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}}
1346  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1347  \label{eq-zab-hydro} \\  \label{eq-zab-hydro} \\
1348  \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{
1349  \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} \\
1350  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\
1351  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zab-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zab-heat} \\
# Line 1265  Here, the objective is to drop the depth Line 1358  Here, the objective is to drop the depth
1358  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
1359  yield the ``truly'' incompressible Boussinesq equations:  yield the ``truly'' incompressible Boussinesq equations:
1360  \begin{eqnarray}  \begin{eqnarray}
1361  \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}}
1362  _{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}}}
1363  \label{eq-ztb-hmom} \\  \label{eq-ztb-hmom} \\
1364  \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}}
1365  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1366  \label{eq-ztb-hydro} \\  \label{eq-ztb-hydro} \\
1367  \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 1287  retain compressibility effects in the de Line 1380  retain compressibility effects in the de
1380  density thus:  density thus:
1381  \begin{equation*}  \begin{equation*}
1382  \rho =\rho _{o}+\rho ^{\prime }  \rho =\rho _{o}+\rho ^{\prime }
1383  \end{equation*}%  \end{equation*}
1384  We then assert that variations with depth of $\rho _{o}$ are unimportant  We then assert that variations with depth of $\rho _{o}$ are unimportant
1385  while the compressible effects in $\rho ^{\prime }$ are:  while the compressible effects in $\rho ^{\prime }$ are:
1386  \begin{equation*}  \begin{equation*}
1387  \rho _{o}=\rho _{c}  \rho _{o}=\rho _{c}
1388  \end{equation*}%  \end{equation*}
1389  \begin{equation*}  \begin{equation*}
1390  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}
1391  \end{equation*}%  \end{equation*}
1392  This then yields what we can call the semi-compressible Boussinesq  This then yields what we can call the semi-compressible Boussinesq
1393  equations:  equations:
1394  \begin{eqnarray}  \begin{eqnarray}
1395  \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}}
1396  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{%  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{
1397  \mathcal{F}}}  \label{eq:ocean-mom} \\  \mathcal{F}}}  \label{eq:ocean-mom} \\
1398  \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
1399  _{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 1311  _{c}}\frac{\partial p^{\prime }}{\partia Line 1404  _{c}}\frac{\partial p^{\prime }}{\partia
1404  \\  \\
1405  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\
1406  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}
1407  \end{eqnarray}%  \end{eqnarray}
1408  Note that the hydrostatic pressure of the resting fluid, including that  Note that the hydrostatic pressure of the resting fluid, including that
1409  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
1410  dynamics.  dynamics.
# Line 1335  In spherical coordinates, the velocity c Line 1428  In spherical coordinates, the velocity c
1428  and vertical direction respectively, are given by (see Fig.2) :  and vertical direction respectively, are given by (see Fig.2) :
1429    
1430  \begin{equation*}  \begin{equation*}
1431  u=r\cos \phi \frac{D\lambda }{Dt}  u=r\cos \varphi \frac{D\lambda }{Dt}
1432  \end{equation*}  \end{equation*}
1433    
1434  \begin{equation*}  \begin{equation*}
1435  v=r\frac{D\phi }{Dt}\qquad  v=r\frac{D\varphi }{Dt}\qquad
1436  \end{equation*}  \end{equation*}
1437  $\qquad \qquad \qquad \qquad $  $\qquad \qquad \qquad \qquad $
1438    
# Line 1347  $\qquad \qquad \qquad \qquad $ Line 1440  $\qquad \qquad \qquad \qquad $
1440  \dot{r}=\frac{Dr}{Dt}  \dot{r}=\frac{Dr}{Dt}
1441  \end{equation*}  \end{equation*}
1442    
1443  Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial  Here $\varphi $ is the latitude, $\lambda $ the longitude, $r$ the radial
1444  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
1445  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.
1446    
# Line 1355  The `grad' ($\nabla $) and `div' ($\nabl Line 1448  The `grad' ($\nabla $) and `div' ($\nabl
1448  spherical coordinates:  spherical coordinates:
1449    
1450  \begin{equation*}  \begin{equation*}
1451  \nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda }%  \nabla \equiv \left( \frac{1}{r\cos \varphi }\frac{\partial }{\partial \lambda }
1452  ,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r}%  ,\frac{1}{r}\frac{\partial }{\partial \varphi },\frac{\partial }{\partial r}
1453  \right)  \right)
1454  \end{equation*}  \end{equation*}
1455    
1456  \begin{equation*}  \begin{equation*}
1457  \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
1458  \lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\}  \lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\}
1459  +\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}
1460  \end{equation*}  \end{equation*}
1461    
1462  %%%% \end{document}  %tci%\end{document}

Legend:
Removed from v.1.2  
changed lines
  Added in v.1.12

  ViewVC Help
Powered by ViewVC 1.1.22