/[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 1.1 by cnh, Thu Sep 27 17:45:03 2001 UTC revision 1.4 by adcroft, Thu Oct 11 19:36:56 2001 UTC
# Line 1  Line 1 
1  %%%% % $Header$  % $Header$
2  %%%% % $Name$  % $Name$
3  %%%% %\usepackage{oldgerm}  
4  %%%% % I commented the following because it introduced excessive white space  %tci%\documentclass[12pt]{book}
5  %%%% %\usepackage{palatcm}              % better PDF  %tci%\usepackage{amsmath}
6  %%%% % page headers and footers  %tci%\usepackage{html}
7  %%%% %\pagestyle{fancy}  %tci%\usepackage{epsfig}
8  %%%% % referencing  %tci%\usepackage{graphics,subfigure}
9  %%%% %% \newcommand{\refequ}[1]{equation (\ref{equ:#1})}  %tci%\usepackage{array}
10  %%%% %% \newcommand{\refequbig}[1]{Equation (\ref{equ:#1})}  %tci%\usepackage{multirow}
11  %%%% %% \newcommand{\reftab}[1]{Tab.~\ref{tab:#1}}  %tci%\usepackage{fancyhdr}
12  %%%% %% \newcommand{\reftabno}[1]{\ref{tab:#1}}  %tci%\usepackage{psfrag}
13  %%%% %% \newcommand{\reffig}[1]{Fig.~\ref{fig:#1}}  
14  %%%% %% \newcommand{\reffigno}[1]{\ref{fig:#1}}  %tci%%TCIDATA{OutputFilter=Latex.dll}
15  %%%% % stuff for psfrag  %tci%%TCIDATA{LastRevised=Thursday, October 04, 2001 14:41:22}
16  %%%% %% \newcommand{\textinfigure}[1]{{\footnotesize\textbf{\textsf{#1}}}}  %tci%%TCIDATA{<META NAME="GraphicsSave" CONTENT="32">}
17  %%%% %% \newcommand{\mathinfigure}[1]{\small\ensuremath{{#1}}}  %tci%%TCIDATA{Language=American English}
18  %%%% % This allows numbering of subsubsections  
19  %%%% % This changes the the chapter title  %tci%\fancyhead{}
20  %%%% %\renewcommand{\chaptername}{Section}  %tci%\fancyhead[LO]{\slshape \rightmark}
21    %tci%\fancyhead[RE]{\slshape \leftmark}
22    %tci%\fancyhead[RO,LE]{\thepage}
23  %%%% \documentclass[12pt]{book}  %tci%\fancyfoot[CO,CE]{\today}
24  %%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  %tci%\fancyfoot[RO,LE]{ }
25  %%%% \usepackage{amsmath}  %tci%\renewcommand{\headrulewidth}{0.4pt}
26  %%%% \usepackage{html}  %tci%\renewcommand{\footrulewidth}{0.4pt}
27  %%%% \usepackage{epsfig}  %tci%\setcounter{secnumdepth}{3}
28  %%%% \usepackage{graphics,subfigure}  %tci%\input{tcilatex}
29  %%%% \usepackage{array}  
30  %%%% \usepackage{multirow}  %tci%\begin{document}
31  %%%% \usepackage{fancyhdr}  
32  %%%% \usepackage{psfrag}  %tci%\tableofcontents
 %%%%  
 %%%% %TCIDATA{OutputFilter=Latex.dll}  
 %%%% %TCIDATA{LastRevised=Thursday, September 27, 2001 10:59:02}  
 %%%% %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  
33    
 \pagebreak  
34    
35  \part{MITgcm basics}  \part{MIT GCM basics}
36    
37  % Section: Overview  % Section: Overview
38    
# Line 78  MITgcm has a number of novel aspects: Line 56  MITgcm has a number of novel aspects:
56  \begin{itemize}  \begin{itemize}
57  \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
58  hydrodynamical kernel is used to drive forward both atmospheric and oceanic  hydrodynamical kernel is used to drive forward both atmospheric and oceanic
59  models - see fig.1%  models - see fig
60  \marginpar{  \marginpar{
61  Fig.1 One model}\ref{fig:onemodel}  Fig.1 One model}\ref{fig:onemodel}
62    
63  \begin{figure}  %% CNHbegin
64  \begin{center}  \input{part1/one_model_figure}
65  \resizebox{!}{4in}{  %% CNHend
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/onemodel.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:onemodel}  
 \end{figure}  
66    
67  \item it has a non-hydrostatic capability and so can be used to study both  \item it has a non-hydrostatic capability and so can be used to study both
68  small-scale and large scale processes - see fig.2%  small-scale and large scale processes - see fig
69  \marginpar{  \marginpar{
70  Fig.2 All scales}\ref{fig:all-scales}  Fig.2 All scales}\ref{fig:all-scales}
71    
72    %% CNHbegin
73  \begin{figure}  \input{part1/all_scales_figure}
74  \begin{center}  %% CNHend
 \resizebox{!}{4in}{  
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/scales.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:scales}  
 \end{figure}  
   
75    
76  \item finite volume techniques are employed yielding an intuitive  \item finite volume techniques are employed yielding an intuitive
77  discretization and support for the treatment of irregular geometries using  discretization and support for the treatment of irregular geometries using
78  orthogonal curvilinear grids and shaved cells - see fig.3%  orthogonal curvilinear grids and shaved cells - see fig
79  \marginpar{  \marginpar{
80  Fig.3 Finite volumes}\ref{fig:Finite volumes}  Fig.3 Finite volumes}\ref{fig:finite-volumes}
81    
82    %% CNHbegin
83    \input{part1/fvol_figure}
84    %% CNHend
85    
86  \item tangent linear and adjoint counterparts are automatically maintained  \item tangent linear and adjoint counterparts are automatically maintained
87  along with the forward model, permitting sensitivity and optimization  along with the forward model, permitting sensitivity and optimization
# Line 147  atmospheric winds - see fig.2\ref{fig:al Line 109  atmospheric winds - see fig.2\ref{fig:al
109  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
110  of them here. A more detailed description of the underlying formulation,  of them here. A more detailed description of the underlying formulation,
111  numerical algorithm and implementation that lie behind these calculations is  numerical algorithm and implementation that lie behind these calculations is
112  given later. Indeed it is easy to reproduce the results shown here: simply  given later. Indeed many of the illustrative examples shown below can be
113  download the model (the minimum you need is a PC running linux, together  easily reproduced: simply download the model (the minimum you need is a PC
114  with a FORTRAN\ 77 compiler) and follow the examples.  running linux, together with a FORTRAN\ 77 compiler) and follow the examples
115    described in detail in the documentation.
116    
117  \subsection{Global atmosphere: `Held-Suarez' benchmark}  \subsection{Global atmosphere: `Held-Suarez' benchmark}
118    
119  Fig.E1a.\ref{fig:Held-Suarez} is an instaneous plot of the 500$mb$ height  A novel feature of MITgcm is its ability to simulate both atmospheric and
120  field obtained using a 5-level version of the atmospheric pressure isomorph  oceanographic flows at both small and large scales.
 run at 2.8$^{\circ }$ resolution. We see fully developed baroclinic eddies  
 along the northern hemisphere storm track. There are no mountains or  
 land-sea contrast in this calculation, but you can easily put them in. The  
 model is driven by relaxation to a radiative-convective equilibrium profile,  
 following the description set out in Held and Suarez; 1994 designed to test  
 atmospheric hydrodynamical cores - there are no mountains or land-sea  
 contrast. As decribed in Adcroft (2001), a `cubed sphere' is used to  
 descretize the globe permitting a uniform gridding and obviated the need to  
 fourier filter.  
   
 Fig.E1b shows the 5-year mean, zonally averaged potential temperature, zonal  
 wind and meridional overturning streamfunction from the 5-level model.  
   
121    
122  \begin{figure}  Fig.E1a.\ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$
123  \begin{center}  temperature field obtained using the atmospheric isomorph of MITgcm run at
124  \resizebox{!}{4in}{  2.8$^{\circ }$ resolution on the cubed sphere. We see cold air over the pole
125   \rotatebox{90}{  (blue) and warm air along an equatorial band (red). Fully developed
126    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/hscs.eps}  baroclinic eddies spawned in the northern hemisphere storm track are
127   }  evident. There are no mountains or land-sea contrast in this calculation,
128  }  but you can easily put them in. The model is driven by relaxation to a
129  \end{center}  radiative-convective equilibrium profile, following the description set out
130  \label{fig:hscs}  in Held and Suarez; 1994 designed to test atmospheric hydrodynamical cores -
131  \end{figure}  there are no mountains or land-sea contrast.
132    
133    %% CNHbegin
134    \input{part1/cubic_eddies_figure}
135    %% CNHend
136    
137    As described in Adcroft (2001), a `cubed sphere' is used to discretize the
138    globe permitting a uniform gridding and obviated the need to fourier filter.
139    The `vector-invariant' form of MITgcm supports any orthogonal curvilinear
140    grid, of which the cubed sphere is just one of many choices.
141    
142    Fig.E1b shows the 5-year mean, zonally averaged potential temperature, zonal
143    wind and meridional overturning streamfunction from a 20-level version of
144    the model. It compares favorable with more conventional spatial
145    discretization approaches.
146    
147  A regular spherical lat-lon grid can also be used.  A regular spherical lat-lon grid can also be used.
148    
149  \begin{figure}  %% CNHbegin
150  \begin{center}  \input{part1/hs_zave_u_figure}
151  \resizebox{!}{4in}{  %% CNHend
  \rotatebox{90}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/hslatlon.eps}  
  }  
 }  
 \end{center}  
 \label{fig:hslatlon}  
 \end{figure}  
152    
153  \subsection{Ocean gyres}  \subsection{Ocean gyres}
154    
155    Baroclinic instability is a ubiquitous process in the ocean, as well as the
156    atmosphere. Ocean eddies play an important role in modifying the
157    hydrographic structure and current systems of the oceans. Coarse resolution
158    models of the oceans cannot resolve the eddy field and yield rather broad,
159    diffusive patterns of ocean currents. But if the resolution of our models is
160    increased until the baroclinic instability process is resolved, numerical
161    solutions of a different and much more realistic kind, can be obtained.
162    
163    Fig. ?.? shows the surface temperature and velocity field obtained from
164    MITgcm run at $\frac{1}{6}^{\circ }$ horizontal resolution on a $lat-lon$
165    grid in which the pole has been rotated by 90$^{\circ }$ on to the equator
166    (to avoid the converging of meridian in northern latitudes). 21 vertical
167    levels are used in the vertical with a `lopped cell' representation of
168    topography. The development and propagation of anomalously warm and cold
169    eddies can be clearly been seen in the Gulf Stream region. The transport of
170    warm water northward by the mean flow of the Gulf Stream is also clearly
171    visible.
172    
173    %% CNHbegin
174    \input{part1/ocean_gyres_figure}
175    %% CNHend
176    
177    
178  \subsection{Global ocean circulation}  \subsection{Global ocean circulation}
179    
180  Fig.E2a shows the pattern of ocean currents at the surface of a 4$^{\circ }$  Fig.E2a shows the pattern of ocean currents at the surface of a 4$^{\circ }$
181  global ocean model run with 15 vertical levels. The model is driven using  global ocean model run with 15 vertical levels. Lopped cells are used to
182  monthly-mean winds with mixed boundary conditions on temperature and  represent topography on a regular $lat-lon$ grid extending from 70$^{\circ
183  salinity at the surface. Fig.E2b shows the overturning (thermohaline)  }N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with
184  circulation. Lopped cells are used to represent topography on a regular $%  mixed boundary conditions on temperature and salinity at the surface. The
185  lat-lon$ grid extending from 70$^{\circ }N$ to 70$^{\circ }S$.  transfer properties of ocean eddies, convection and mixing is parameterized
186    in this model.
187    
188  \begin{figure}  Fig.E2b shows the meridional overturning circulation of the global ocean in
189  \begin{center}  Sverdrups.
190  \resizebox{!}{4in}{  
191  % \rotatebox{90}{  %%CNHbegin
192    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/ocean_circ_455_2030.eps}  \input{part1/global_circ_figure}
193  % }  %%CNHend
194  }  
195  \end{center}  \subsection{Convection and mixing over topography}
196  \label{fig:horizcirc}  
197  \end{figure}  Dense plumes generated by localized cooling on the continental shelf of the
198    ocean may be influenced by rotation when the deformation radius is smaller
199  \begin{figure}  than the width of the cooling region. Rather than gravity plumes, the
200  \begin{center}  mechanism for moving dense fluid down the shelf is then through geostrophic
201  \resizebox{!}{4in}{  eddies. The simulation shown in the figure (blue is cold dense fluid, red is
202   \rotatebox{90}{  warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to
203   \rotatebox{180}{  trigger convection by surface cooling. The cold, dense water falls down the
204    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/moc.eps}  slope but is deflected along the slope by rotation. It is found that
205   }  entrainment in the vertical plane is reduced when rotational control is
206   }  strong, and replaced by lateral entrainment due to the baroclinic
207  }  instability of the along-slope current.
208  \end{center}  
209  \label{fig:moc}  %%CNHbegin
210  \end{figure}  \input{part1/convect_and_topo}
211    %%CNHend
   
 \subsection{Flow over topography}  
   
 \subsection{Ocean convection}  
   
 Fig.E3 shows convection over a slope using the non-hydrostatic ocean  
 isomorph and lopped cells to respresent topography. .....The grid resolution  
 is  
212    
213  \subsection{Boundary forced internal waves}  \subsection{Boundary forced internal waves}
214    
215  \subsection{Carbon outgassing sensitivity}  The unique ability of MITgcm to treat non-hydrostatic dynamics in the
216    presence of complex geometry makes it an ideal tool to study internal wave
217  Fig.E4 shows....  dynamics and mixing in oceanic canyons and ridges driven by large amplitude
218    barotropic tidal currents imposed through open boundary conditions.
219  \begin{figure}  
220  \begin{center}  Fig. ?.? shows the influence of cross-slope topographic variations on
221  \resizebox{!}{4in}{  internal wave breaking - the cross-slope velocity is in color, the density
222    \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/co209.eps}  contoured. The internal waves are excited by application of open boundary
223  }  conditions on the left.\ They propagate to the sloping boundary (represented
224  \end{center}  using MITgcm's finite volume spatial discretization) where they break under
225  \label{fig:co2mrt}  nonhydrostatic dynamics.
226  \end{figure}  
227    %%CNHbegin
228    \input{part1/boundary_forced_waves}
229    %%CNHend
230    
231    \subsection{Parameter sensitivity using the adjoint of MITgcm}
232    
233    Forward and tangent linear counterparts of MITgcm are supported using an
234    `automatic adjoint compiler'. These can be used in parameter sensitivity and
235    data assimilation studies.
236    
237    As one example of application of the MITgcm adjoint, Fig.E4 maps the
238    gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude
239    of the overturning streamfunction shown in fig?.? at 40$^{\circ }$N and $
240    \mathcal{H}$ is the air-sea heat flux 100 years before. We see that $J$ is
241    sensitive to heat fluxes over the Labrador Sea, one of the important sources
242    of deep water for the thermohaline circulations. This calculation also
243    yields sensitivities to all other model parameters.
244    
245    %%CNHbegin
246    \input{part1/adj_hf_ocean_figure}
247    %%CNHend
248    
249    \subsection{Global state estimation of the ocean}
250    
251    An important application of MITgcm is in state estimation of the global
252    ocean circulation. An appropriately defined `cost function', which measures
253    the departure of the model from observations (both remotely sensed and
254    insitu) over an interval of time, is minimized by adjusting `control
255    parameters' such as air-sea fluxes, the wind field, the initial conditions
256    etc. Figure ?.? shows an estimate of the time-mean surface elevation of the
257    ocean obtained by bringing the model in to consistency with altimetric and
258    in-situ observations over the period 1992-1997.
259    
260    %% CNHbegin
261    \input{part1/globes_figure}
262    %% CNHend
263    
264    \subsection{Ocean biogeochemical cycles}
265    
266    MITgcm is being used to study global biogeochemical cycles in the ocean. For
267    example one can study the effects of interannual changes in meteorological
268    forcing and upper ocean circulation on the fluxes of carbon dioxide and
269    oxygen between the ocean and atmosphere. The figure shows the annual air-sea
270    flux of oxygen and its relation to density outcrops in the southern oceans
271    from a single year of a global, interannually varying simulation.
272    
273    %%CNHbegin
274    \input{part1/biogeo_figure}
275    %%CNHend
276    
277    \subsection{Simulations of laboratory experiments}
278    
279    Figure ?.? shows MITgcm being used to simulate a laboratory experiment
280    enquiring in to the dynamics of the Antarctic Circumpolar Current (ACC). An
281    initially homogeneous tank of water ($1m$ in diameter) is driven from its
282    free surface by a rotating heated disk. The combined action of mechanical
283    and thermal forcing creates a lens of fluid which becomes baroclinically
284    unstable. The stratification and depth of penetration of the lens is
285    arrested by its instability in a process analogous to that whic sets the
286    stratification of the ACC.
287    
288    %%CNHbegin
289    \input{part1/lab_figure}
290    %%CNHend
291    
292  % $Header$  % $Header$
293  % $Name$  % $Name$
# Line 262  Fig.E4 shows.... Line 296  Fig.E4 shows....
296    
297  To render atmosphere and ocean models from one dynamical core we exploit  To render atmosphere and ocean models from one dynamical core we exploit
298  `isomorphisms' between equation sets that govern the evolution of the  `isomorphisms' between equation sets that govern the evolution of the
299  respective fluids - see fig.4%  respective fluids - see fig.4
300  \marginpar{  \marginpar{
301  Fig.4. Isomorphisms}. One system of hydrodynamical equations is written down  Fig.4. Isomorphisms}. One system of hydrodynamical equations is written down
302  and encoded. The model variables have different interpretations depending on  and encoded. The model variables have different interpretations depending on
# Line 270  whether the atmosphere or ocean is being Line 304  whether the atmosphere or ocean is being
304  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are  vertical coordinate `$r$' is interpreted as pressure, $p$, if we are
305  modeling the atmosphere and height, $z$, if we are modeling the ocean.  modeling the atmosphere and height, $z$, if we are modeling the ocean.
306    
307    %%CNHbegin
308    \input{part1/zandpcoord_figure.tex}
309    %%CNHend
310    
311  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
312  velocity $\vec{\mathbf{v}}$, active tracers $\theta $ and $S$, a  velocity $\vec{\mathbf{v}}$, active tracers $\theta $ and $S$, a
313  `geopotential' $\phi $ and density $\rho =\rho (\theta ,S,p)$ which may  `geopotential' $\phi $ and density $\rho =\rho (\theta ,S,p)$ which may
314  depend on $\theta $, $S$, and $p$. The equations that govern the evolution  depend on $\theta $, $S$, and $p$. The equations that govern the evolution
315  of these fields, obtained by applying the laws of classical mechanics and  of these fields, obtained by applying the laws of classical mechanics and
316  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of  thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of
317  a generic vertical coordinate, $r$, see fig.5%  a generic vertical coordinate, $r$, see fig.5
318  \marginpar{  \marginpar{
319  Fig.5 The vertical coordinate of model}:  Fig.5 The vertical coordinate of model}:
320    
321  \begin{figure}  %%CNHbegin
322  \begin{center}  \input{part1/vertcoord_figure.tex}
323  \resizebox{!}{4in}{  %%CNHend
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/vertcoord.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:vertcoord}  
 \end{figure}  
324    
325  \begin{equation*}  \begin{equation*}
326  \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}}
327  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}%  \right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}}
328  \text{ horizontal mtm}  \text{ horizontal mtm}
329  \end{equation*}  \end{equation*}
330    
331  \begin{equation*}  \begin{equation*}
332  \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{
333  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{
334  vertical mtm}  vertical mtm}
335  \end{equation*}  \end{equation*}
336    
337  \begin{equation}  \begin{equation}
338  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{%  \mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{
339  \partial r}=0\text{ continuity}  \label{eq:continuous}  \partial r}=0\text{ continuity}  \label{eq:continuous}
340  \end{equation}  \end{equation}
341    
342  \begin{equation*}  \begin{equation*}
343  b=b(\theta ,S,r)\text{ equation of state}  b=b(\theta ,S,r)\text{ equation of state}
344  \end{equation*}  \end{equation*}
345    
346  \begin{equation*}  \begin{equation*}
347  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{  potential temperature}  \frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature}
348  \end{equation*}  \end{equation*}
349    
350  \begin{equation*}  \begin{equation*}
351  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{  humidity/salinity}  \frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity}
352  \end{equation*}  \end{equation*}
353    
354  Here:  Here:
355    
356  \begin{equation*}  \begin{equation*}
357  r\text{ is the vertical coordinate}  r\text{ is the vertical coordinate}
358  \end{equation*}  \end{equation*}
359    
360  \begin{equation*}  \begin{equation*}
361  \frac{D}{Dt}=\frac{\partial }{\partial t}+\vec{\mathbf{v}}\cdot \nabla \text{  \frac{D}{Dt}=\frac{\partial }{\partial t}+\vec{\mathbf{v}}\cdot \nabla \text{
362  is the total derivative}  is the total derivative}
363  \end{equation*}  \end{equation*}
364    
365  \begin{equation*}  \begin{equation*}
366  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}%  \mathbf{\nabla }=\mathbf{\nabla }_{h}+\widehat{k}\frac{\partial }{\partial r}
367  \text{ is the `grad' operator}  \text{ is the `grad' operator}
368  \end{equation*}  \end{equation*}
369  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}%  with $\mathbf{\nabla }_{h}$ operating in the horizontal and $\widehat{k}
370  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$  \frac{\partial }{\partial r}$ operating in the vertical, where $\widehat{k}$
371  is a unit vector in the vertical  is a unit vector in the vertical
372    
373  \begin{equation*}  \begin{equation*}
374  t\text{ is time}  t\text{ is time}
375  \end{equation*}  \end{equation*}
376    
377  \begin{equation*}  \begin{equation*}
378  \vec{\mathbf{v}}=(u,v,\dot{r})=(\vec{\mathbf{v}}_{h},\dot{r})\text{ is the  \vec{\mathbf{v}}=(u,v,\dot{r})=(\vec{\mathbf{v}}_{h},\dot{r})\text{ is the
379  velocity}  velocity}
380  \end{equation*}  \end{equation*}
381    
382  \begin{equation*}  \begin{equation*}
383  \phi \text{ is the `pressure'/`geopotential'}  \phi \text{ is the `pressure'/`geopotential'}
384  \end{equation*}  \end{equation*}
385    
386  \begin{equation*}  \begin{equation*}
387  \vec{\Omega}\text{ is the Earth's rotation}  \vec{\Omega}\text{ is the Earth's rotation}
388  \end{equation*}  \end{equation*}
389    
390  \begin{equation*}  \begin{equation*}
391  b\text{ is the `buoyancy'}  b\text{ is the `buoyancy'}
392  \end{equation*}  \end{equation*}
393    
394  \begin{equation*}  \begin{equation*}
395  \theta \text{ is potential temperature}  \theta \text{ is potential temperature}
396  \end{equation*}  \end{equation*}
397    
398  \begin{equation*}  \begin{equation*}
399  S\text{ is specific humidity in the atmosphere; salinity in the ocean}  S\text{ is specific humidity in the atmosphere; salinity in the ocean}
400  \end{equation*}  \end{equation*}
401    
402  \begin{equation*}  \begin{equation*}
403  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{%  \mathcal{F}_{\vec{\mathbf{v}}}\text{ are forcing and dissipation of }\vec{
404  \mathbf{v}}  \mathbf{v}}
405  \end{equation*}  \end{equation*}
406    
407  \begin{equation*}  \begin{equation*}
408  \mathcal{Q}_{\theta }\mathcal{\ }\text{are forcing and dissipation of }%  \mathcal{Q}_{\theta }\mathcal{\ }\text{are forcing and dissipation of }\theta
 \theta  
409  \end{equation*}  \end{equation*}
410    
411  \begin{equation*}  \begin{equation*}
# Line 406  at fixed and moving $r$ surfaces we set Line 434  at fixed and moving $r$ surfaces we set
434  Here  Here
435    
436  \begin{equation*}  \begin{equation*}
437  R_{moving}=R_{o}+\eta  R_{moving}=R_{o}+\eta
438  \end{equation*}  \end{equation*}
439  where $R_{o}(x,y)$ is the `$r-$value' (height or pressure, depending on  where $R_{o}(x,y)$ is the `$r-$value' (height or pressure, depending on
440  whether we are in the atmosphere or ocean) of the `moving surface' in the  whether we are in the atmosphere or ocean) of the `moving surface' in the
# Line 417  of motion. Line 445  of motion.
445    
446  \begin{equation}  \begin{equation}
447  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}  \vec{\mathbf{v}}\cdot \vec{\mathbf{n}}=0  \label{eq:noflow}
448  \end{equation}%  \end{equation}
449  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.  where $\vec{\mathbf{n}}$ is the normal to a solid boundary.
450    
451  \subsection{Atmosphere}  \subsection{Atmosphere}
# Line 454  where Line 482  where
482    
483  \begin{equation*}  \begin{equation*}
484  T\text{ is absolute temperature}  T\text{ is absolute temperature}
485  \end{equation*}%  \end{equation*}
486  \begin{equation*}  \begin{equation*}
487  p\text{ is the pressure}  p\text{ is the pressure}
488  \end{equation*}%  \end{equation*}
489  \begin{eqnarray*}  \begin{eqnarray*}
490  &&z\text{ is the height of the pressure surface} \\  &&z\text{ is the height of the pressure surface} \\
491  &&g\text{ is the acceleration due to gravity}  &&g\text{ is the acceleration due to gravity}
# Line 467  In the above the ideal gas law, $p=\rho Line 495  In the above the ideal gas law, $p=\rho
495  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)  the Exner function $\Pi (p)$ given by (see Appendix Atmosphere)
496  \begin{equation}  \begin{equation}
497  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{eq:exner}
498  \end{equation}%  \end{equation}
499  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
500  constant and $c_{p}$ the specific heat of air at constant pressure.  constant and $c_{p}$ the specific heat of air at constant pressure.
501    
502  At the top of the atmosphere (which is `fixed' in our $r$ coordinate):  At the top of the atmosphere (which is `fixed' in our $r$ coordinate):
503    
504  \begin{equation*}  \begin{equation*}
505  R_{fixed}=p_{top}=0  R_{fixed}=p_{top}=0
506  \end{equation*}  \end{equation*}
507  In a resting atmosphere the elevation of the mountains at the bottom is  In a resting atmosphere the elevation of the mountains at the bottom is
508  given by  given by
509  \begin{equation*}  \begin{equation*}
510  R_{moving}=R_{o}(x,y)=p_{o}(x,y)  R_{moving}=R_{o}(x,y)=p_{o}(x,y)
511  \end{equation*}  \end{equation*}
512  i.e. the (hydrostatic) pressure at the top of the mountains in a resting  i.e. the (hydrostatic) pressure at the top of the mountains in a resting
513  atmosphere.  atmosphere.
# Line 517  At the bottom of the ocean: $R_{fixed}(x Line 545  At the bottom of the ocean: $R_{fixed}(x
545    
546  The surface of the ocean is given by: $R_{moving}=\eta $  The surface of the ocean is given by: $R_{moving}=\eta $
547    
548  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 $
549  R_{o}=Z_{o}=0$.  R_{o}=Z_{o}=0$.
550    
551  Boundary conditions are:  Boundary conditions are:
# Line 525  Boundary conditions are: Line 553  Boundary conditions are:
553  \begin{eqnarray}  \begin{eqnarray}
554  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}
555  \\  \\
556  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)
557  \label{eq:moving-bc-ocean}}  \label{eq:moving-bc-ocean}}
558  \end{eqnarray}  \end{eqnarray}
559  where $\eta $ is the elevation of the free surface.  where $\eta $ is the elevation of the free surface.
# Line 542  Let us separate $\phi $ in to surface, h Line 570  Let us separate $\phi $ in to surface, h
570  \begin{equation}  \begin{equation}
571  \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)
572  \label{eq:phi-split}  \label{eq:phi-split}
573  \end{equation}%  \end{equation}
574  and write eq(\ref{incompressible}a,b) in the form:  and write eq(\ref{incompressible}a,b) in the form:
575    
576  \begin{equation}  \begin{equation}
# Line 556  _{nh}=\vec{\mathbf{G}}_{\vec{v}_{h}}  \l Line 584  _{nh}=\vec{\mathbf{G}}_{\vec{v}_{h}}  \l
584  \end{equation}  \end{equation}
585    
586  \begin{equation}  \begin{equation}
587  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{%  \epsilon _{nh}\frac{\partial \dot{r}}{\partial t}+\frac{\partial \phi _{nh}}{
588  \partial r}=G_{\dot{r}}  \label{eq:mom-w}  \partial r}=G_{\dot{r}}  \label{eq:mom-w}
589  \end{equation}  \end{equation}
590  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.  Here $\epsilon _{nh}$ is a non-hydrostatic parameter.
591    
592  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
593  {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
594  terms in the momentum equations. In spherical coordinates they take the form%  terms in the momentum equations. In spherical coordinates they take the form
595  \footnote{%  \footnote{
596  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms  In the hydrostatic primitive equations (\textbf{HPE}) all underlined terms
597  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref%  in (\ref{eq:gu-speherical}), (\ref{eq:gv-spherical}) and (\ref
598  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in  {eq:gw-spherical}) are omitted; the singly-underlined terms are included in
599  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (%  the quasi-hydrostatic model (\textbf{QH}). The fully non-hydrostatic model (
600  \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
601  discussion:  discussion:
602    
# Line 580  $-\left\{ \underline{\frac{u\dot{r}}{{r} Line 608  $-\left\{ \underline{\frac{u\dot{r}}{{r}
608  \\  \\
609  $-\left\{ -2\Omega v\sin lat+\underline{2\Omega \dot{r}\cos lat}\right\} $  $-\left\{ -2\Omega v\sin lat+\underline{2\Omega \dot{r}\cos lat}\right\} $
610  \\  \\
611  $+\mathcal{F}_{u}$%  $+\mathcal{F}_{u}$
612  \end{tabular}%  \end{tabular}
613  \ \right\} \left\{  \ \right\} \left\{
614  \begin{tabular}{l}  \begin{tabular}{l}
615  \textit{advection} \\  \textit{advection} \\
616  \textit{metric} \\  \textit{metric} \\
617  \textit{Coriolis} \\  \textit{Coriolis} \\
618  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
619  \end{tabular}%  \end{tabular}
620  \ \right. \qquad   \label{eq:gu-speherical}  \ \right. \qquad  \label{eq:gu-speherical}
621  \end{equation}  \end{equation}
622    
623  \begin{equation}  \begin{equation}
# Line 599  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\ Line 627  $G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\
627  $-\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 lat}{{r}}\right\}
628  $ \\  $ \\
629  $-\left\{ -2\Omega u\sin lat\right\} $ \\  $-\left\{ -2\Omega u\sin lat\right\} $ \\
630  $+\mathcal{F}_{v}$%  $+\mathcal{F}_{v}$
631  \end{tabular}%  \end{tabular}
632  \ \right\} \left\{  \ \right\} \left\{
633  \begin{tabular}{l}  \begin{tabular}{l}
634  \textit{advection} \\  \textit{advection} \\
635  \textit{metric} \\  \textit{metric} \\
636  \textit{Coriolis} \\  \textit{Coriolis} \\
637  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
638  \end{tabular}%  \end{tabular}
639  \ \right. \qquad   \label{eq:gv-spherical}  \ \right. \qquad  \label{eq:gv-spherical}
640  \end{equation}%  \end{equation}
641  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
642    
643  \begin{equation}  \begin{equation}
644  \left.  \left.
# Line 618  $+\mathcal{F}_{v}$% Line 646  $+\mathcal{F}_{v}$%
646  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\  $G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\
647  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\  $+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\
648  ${+}\underline{{2\Omega u\cos lat}}$ \\  ${+}\underline{{2\Omega u\cos lat}}$ \\
649  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$%  $\underline{\underline{\mathcal{F}_{\dot{r}}}}$
650  \end{tabular}%  \end{tabular}
651  \ \right\} \left\{  \ \right\} \left\{
652  \begin{tabular}{l}  \begin{tabular}{l}
653  \textit{advection} \\  \textit{advection} \\
654  \textit{metric} \\  \textit{metric} \\
655  \textit{Coriolis} \\  \textit{Coriolis} \\
656  \textit{\ Forcing/Dissipation}%  \textit{\ Forcing/Dissipation}
657  \end{tabular}%  \end{tabular}
658  \ \right.   \label{eq:gw-spherical}  \ \right.  \label{eq:gw-spherical}
659  \end{equation}%  \end{equation}
660  \qquad \qquad \qquad \qquad \qquad  \qquad \qquad \qquad \qquad \qquad
661    
662  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 `$lat$
663  ' is latitude.  ' is latitude.
664    
665  Grad and div operators in spherical coordinates are defined in appendix  Grad and div operators in spherical coordinates are defined in appendix
666  OPERATORS.%  OPERATORS.
667  \marginpar{  \marginpar{
668  Fig.6 Spherical polar coordinate system.}  Fig.6 Spherical polar coordinate system.}
669    
670  \begin{figure}  %%CNHbegin
671  \begin{center}  \input{part1/sphere_coord_figure.tex}
672  \resizebox{!}{4in}{  %%CNHend
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/spherical-polar.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:spcoord}  
 \end{figure}  
   
673    
674  \subsubsection{Shallow atmosphere approximation}  \subsubsection{Shallow atmosphere approximation}
675    
# Line 661  hydrostatic balance and the `traditional Line 679  hydrostatic balance and the `traditional
679  Coriolis force is treated approximately and the shallow atmosphere  Coriolis force is treated approximately and the shallow atmosphere
680  approximation is made.\ The MITgcm need not make the `traditional  approximation is made.\ The MITgcm need not make the `traditional
681  approximation'. To be able to support consistent non-hydrostatic forms the  approximation'. To be able to support consistent non-hydrostatic forms the
682  shallow atmosphere approximation can be relaxed - when dividing through by $r  shallow atmosphere approximation can be relaxed - when dividing through by $
683  $ 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 $a$,
684  the radius of the earth.  the radius of the earth.
685    
686  \subsubsection{Hydrostatic and quasi-hydrostatic forms}  \subsubsection{Hydrostatic and quasi-hydrostatic forms}
# Line 674  terms in Eqs. (\ref{eq:gu-speherical} $\ Line 692  terms in Eqs. (\ref{eq:gu-speherical} $\
692  are neglected and `${r}$' is replaced by `$a$', the mean radius of the  are neglected and `${r}$' is replaced by `$a$', the mean radius of the
693  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
694  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
695  computed at all other levels by integration of the hydrostatic relation, eq(%  computed at all other levels by integration of the hydrostatic relation, eq(
696  \ref{eq:hydrostatic}).  \ref{eq:hydrostatic}).
697    
698  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between  In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between
699  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
700  \phi $ Coriolis term are not neglected and are balanced by a non-hydrostatic  \phi $ Coriolis term are not neglected and are balanced by a non-hydrostatic
701  contribution to the pressure field: only the terms underlined twice in Eqs. (%  contribution to the pressure field: only the terms underlined twice in Eqs. (
702  \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
703  and, simultaneously, the shallow atmosphere approximation is relaxed. In  and, simultaneously, the shallow atmosphere approximation is relaxed. In
704  \textbf{QH}\ \textit{all} the metric terms are retained and the full  \textbf{QH}\ \textit{all} the metric terms are retained and the full
# Line 688  variation of the radial position of a pa Line 706  variation of the radial position of a pa
706  vertical momentum equation (\ref{eq:mom-w}) becomes:  vertical momentum equation (\ref{eq:mom-w}) becomes:
707    
708  \begin{equation*}  \begin{equation*}
709  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat  \frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat
710  \end{equation*}  \end{equation*}
711  making a small correction to the hydrostatic pressure.  making a small correction to the hydrostatic pressure.
712    
# Line 704  only a quasi-non-hydrostatic atmospheric Line 722  only a quasi-non-hydrostatic atmospheric
722    
723  \paragraph{Non-hydrostatic Ocean}  \paragraph{Non-hydrostatic Ocean}
724    
725  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref%  In the non-hydrostatic ocean model all terms in equations Eqs.(\ref
726  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A  {eq:gu-speherical} $\rightarrow $\ \ref{eq:gw-spherical}) are retained. A
727  three dimensional elliptic equation must be solved subject to Neumann  three dimensional elliptic equation must be solved subject to Neumann
728  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
# Line 717  and Bromley, 1995; Marshall et.al.\ 1997 Line 735  and Bromley, 1995; Marshall et.al.\ 1997
735    
736  \paragraph{Quasi-nonhydrostatic Atmosphere}  \paragraph{Quasi-nonhydrostatic Atmosphere}
737    
738  In the non-hydrostatic version of our atmospheric model we approximate $\dot{%  In the non-hydrostatic version of our atmospheric model we approximate $\dot{
739  r}$ 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})
740  (but only here) by:  (but only here) by:
741    
742  \begin{equation}  \begin{equation}
743  \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}
744  \end{equation}%  \end{equation}
745  where $p_{hy}$ is the hydrostatic pressure.  where $p_{hy}$ is the hydrostatic pressure.
746    
747  \subsubsection{Summary of equation sets supported by model}  \subsubsection{Summary of equation sets supported by model}
# Line 751  equations in $z-$coordinates are support Line 769  equations in $z-$coordinates are support
769    
770  \subparagraph{Non-hydrostatic}  \subparagraph{Non-hydrostatic}
771    
772  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$%  Non-hydrostatic forms of the incompressible Boussinesq equations in $z-$
773  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref%  coordinates are supported - see eqs(\ref{eq:ocean-mom}) to (\ref
774  {eq:ocean-salt}).  {eq:ocean-salt}).
775    
776  \subsection{Solution strategy}  \subsection{Solution strategy}
777    
778  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{
779  NH} models is summarized in Fig.7.%  NH} models is summarized in Fig.7.
780  \marginpar{  \marginpar{
781  Fig.7 Solution strategy} Under all dynamics, a 2-d elliptic equation is  Fig.7 Solution strategy} Under all dynamics, a 2-d elliptic equation is
782  first solved to find the surface pressure and the hydrostatic pressure at  first solved to find the surface pressure and the hydrostatic pressure at
# Line 769  forward and $\dot{r}$ found from continu Line 787  forward and $\dot{r}$ found from continu
787  stepping forward the horizontal momentum equations; $\dot{r}$ is found by  stepping forward the horizontal momentum equations; $\dot{r}$ is found by
788  stepping forward the vertical momentum equation.  stepping forward the vertical momentum equation.
789    
790  \begin{figure}  %%CNHbegin
791  \begin{center}  \input{part1/solution_strategy_figure.tex}
792  \resizebox{!}{4in}{  %%CNHend
  \rotatebox{90}{  
  \rotatebox{180}{  
   \includegraphics*[0.2in,0.7in][10.5in,10.5in]{part1/soln_strategy.eps}  
  }  
  }  
 }  
 \end{center}  
 \label{fig:solnstart}  
 \end{figure}  
   
793    
794  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
795  course, some complication that goes with the inclusion of $\cos \phi \ $%  course, some complication that goes with the inclusion of $\cos \phi \ $
796  Coriolis terms and the relaxation of the shallow atmosphere approximation.  Coriolis terms and the relaxation of the shallow atmosphere approximation.
797  But this leads to negligible increase in computation. In \textbf{NH}, in  But this leads to negligible increase in computation. In \textbf{NH}, in
798  contrast, one additional elliptic equation - a three-dimensional one - must  contrast, one additional elliptic equation - a three-dimensional one - must
# Line 808  Hydrostatic pressure is obtained by inte Line 816  Hydrostatic pressure is obtained by inte
816  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:
817    
818  \begin{equation*}  \begin{equation*}
819  \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}
820  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr  \right] _{r}^{R_{o}}=\int_{r}^{R_{o}}-bdr
821  \end{equation*}  \end{equation*}
822  and so  and so
823    
# Line 826  atmospheric pressure pushing down on the Line 834  atmospheric pressure pushing down on the
834    
835  \subsubsection{Surface pressure}  \subsubsection{Surface pressure}
836    
837  The surface pressure equation can be obtained by integrating continuity, (%  The surface pressure equation can be obtained by integrating continuity, (
838  \ref{eq:continuous})c, vertically from $r=R_{fixed}$ to $r=R_{moving}$  \ref{eq:continuous})c, vertically from $r=R_{fixed}$ to $r=R_{moving}$
839    
840  \begin{equation*}  \begin{equation*}
841  \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}
842  }_{h}+\partial _{r}\dot{r}\right) dr=0  }_{h}+\partial _{r}\dot{r}\right) dr=0
843  \end{equation*}  \end{equation*}
844    
845  Thus:  Thus:
846    
847  \begin{equation*}  \begin{equation*}
848  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta  \frac{\partial \eta }{\partial t}+\vec{\mathbf{v}}.\nabla \eta
849  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}%  +\int_{R_{fixed}}^{R_{moving}}\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}
850  _{h}dr=0  _{h}dr=0
851  \end{equation*}  \end{equation*}
852  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 $
853  r $. The above can be rearranged to yield, using Leibnitz's theorem:  r $. The above can be rearranged to yield, using Leibnitz's theorem:
854    
855  \begin{equation}  \begin{equation}
856  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot  \frac{\partial \eta }{\partial t}+\mathbf{\nabla }_{h}\cdot
857  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}  \int_{R_{fixed}}^{R_{moving}}\vec{\mathbf{v}}_{h}dr=\text{source}
858  \label{eq:free-surface}  \label{eq:free-surface}
859  \end{equation}%  \end{equation}
860  where we have incorporated a source term.  where we have incorporated a source term.
861    
862  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential  Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential
863  (atmospheric model), in (\ref{mtm-split}), the horizontal gradient term can  (atmospheric model), in (\ref{mtm-split}), the horizontal gradient term can
864  be written  be written
865  \begin{equation}  \begin{equation}
866  \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)
867  \label{eq:phi-surf}  \label{eq:phi-surf}
868  \end{equation}%  \end{equation}
869  where $b_{s}$ is the buoyancy at the surface.  where $b_{s}$ is the buoyancy at the surface.
870    
871  In the hydrostatic limit ($\epsilon _{nh}=0$), Eqs(\ref{eq:mom-h}), (\ref%  In the hydrostatic limit ($\epsilon _{nh}=0$), Eqs(\ref{eq:mom-h}), (\ref
872  {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
873  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free  elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free
874  surface' and `rigid lid' approaches are available.  surface' and `rigid lid' approaches are available.
875    
876  \subsubsection{Non-hydrostatic pressure}  \subsubsection{Non-hydrostatic pressure}
877    
878  Taking the horizontal divergence of (\ref{hor-mtm}) and adding $\frac{%  Taking the horizontal divergence of (\ref{hor-mtm}) and adding $\frac{
879  \partial }{\partial r}$ of (\ref{vertmtm}), invoking the continuity equation  \partial }{\partial r}$ of (\ref{vertmtm}), invoking the continuity equation
880  (\ref{incompressible}), we deduce that:  (\ref{incompressible}), we deduce that:
881    
882  \begin{equation}  \begin{equation}
883  \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{
884  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .%  \nabla }_{h}^{2}\phi _{s}+\mathbf{\nabla }^{2}\phi _{hyd}\right) =\nabla .
885  \vec{\mathbf{F}}  \label{eq:3d-invert}  \vec{\mathbf{F}}  \label{eq:3d-invert}
886  \end{equation}  \end{equation}
887    
# Line 893  coasts (in the ocean) and the bottom: Line 901  coasts (in the ocean) and the bottom:
901  \end{equation}  \end{equation}
902  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
903  kinematic condition (\ref{nonormalflow}) is also applied to the vertical  kinematic condition (\ref{nonormalflow}) is also applied to the vertical
904  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 $
905  \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
906  tangential component of velocity, $v_{T}$, at all solid boundaries,  tangential component of velocity, $v_{T}$, at all solid boundaries,
907  depending on the form chosen for the dissipative terms in the momentum  depending on the form chosen for the dissipative terms in the momentum
# Line 910  where Line 918  where
918  \begin{equation*}  \begin{equation*}
919  \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
920  _{s}+\mathbf{\nabla }\phi _{hyd}\right)  _{s}+\mathbf{\nabla }\phi _{hyd}\right)
921  \end{equation*}%  \end{equation*}
922  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem  presenting inhomogeneous Neumann boundary conditions to the Elliptic problem
923  (\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
924  exploit classical 3D potential theory and, by introducing an appropriately  exploit classical 3D potential theory and, by introducing an appropriately
925  chosen $\delta $-function sheet of `source-charge', replace the inhomogenous  chosen $\delta $-function sheet of `source-charge', replace the
926  boundary condition on pressure by a homogeneous one. The source term $rhs$  inhomogeneous boundary condition on pressure by a homogeneous one. The
927  in (\ref{eq:3d-invert}) is the divergence of the vector $\vec{\mathbf{F}}.$  source term $rhs$ in (\ref{eq:3d-invert}) is the divergence of the vector $
928  By simultaneously setting $%  \vec{\mathbf{F}}.$ By simultaneously setting $
929  \begin{array}{l}  \begin{array}{l}
930  \widehat{n}.\vec{\mathbf{F}}%  \widehat{n}.\vec{\mathbf{F}}
931  \end{array}%  \end{array}
932  =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
933  self-consistent but simpler homogenised Elliptic problem is obtained:  self-consistent but simpler homogenized Elliptic problem is obtained:
934    
935  \begin{equation*}  \begin{equation*}
936  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad  \nabla ^{2}\phi _{nh}=\nabla .\widetilde{\vec{\mathbf{F}}}\qquad
937  \end{equation*}%  \end{equation*}
938  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such  where $\widetilde{\vec{\mathbf{F}}}$ is a modified $\vec{\mathbf{F}}$ such
939  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
940  {eq:inhom-neumann-nh}) the modified boundary condition becomes:  {eq:inhom-neumann-nh}) the modified boundary condition becomes:
941    
942  \begin{equation}  \begin{equation}
# Line 957  Many forms of momentum dissipation are a Line 965  Many forms of momentum dissipation are a
965  biharmonic frictions are commonly used:  biharmonic frictions are commonly used:
966    
967  \begin{equation}  \begin{equation}
968  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}}
969  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}  +A_{4}\nabla _{h}^{4}v  \label{eq:dissipation}
970  \end{equation}  \end{equation}
971  where $A_{h}$ and $A_{v}\ $are (constant) horizontal and vertical viscosity  where $A_{h}$ and $A_{v}\ $are (constant) horizontal and vertical viscosity
# Line 968  friction. These coefficients are the sam Line 976  friction. These coefficients are the sam
976    
977  The mixing terms for the temperature and salinity equations have a similar  The mixing terms for the temperature and salinity equations have a similar
978  form to that of momentum except that the diffusion tensor can be  form to that of momentum except that the diffusion tensor can be
979  non-diagonal and have varying coefficients. $\qquad $%  non-diagonal and have varying coefficients. $\qquad $
980  \begin{equation}  \begin{equation}
981  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
982  _{h}^{4}(T,S)  \label{eq:diffusion}  _{h}^{4}(T,S)  \label{eq:diffusion}
983  \end{equation}  \end{equation}
984  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $%  where $\underline{\underline{K}}\ $is the diffusion tensor and the $K_{4}\ $
985  horizontal coefficient for biharmonic diffusion. In the simplest case where  horizontal coefficient for biharmonic diffusion. In the simplest case where
986  the subgrid-scale fluxes of heat and salt are parameterized with constant  the subgrid-scale fluxes of heat and salt are parameterized with constant
987  horizontal and vertical diffusion coefficients, $\underline{\underline{K}}$,  horizontal and vertical diffusion coefficients, $\underline{\underline{K}}$,
# Line 984  reduces to a diagonal matrix with consta Line 992  reduces to a diagonal matrix with consta
992  \begin{array}{ccc}  \begin{array}{ccc}
993  K_{h} & 0 & 0 \\  K_{h} & 0 & 0 \\
994  0 & K_{h} & 0 \\  0 & K_{h} & 0 \\
995  0 & 0 & K_{v}%  0 & 0 & K_{v}
996  \end{array}  \end{array}
997  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}  \right) \qquad \qquad \qquad  \label{eq:diagonal-diffusion-tensor}
998  \end{equation}  \end{equation}
# Line 994  salinity ... ). Line 1002  salinity ... ).
1002    
1003  \subsection{Vector invariant form}  \subsection{Vector invariant form}
1004    
1005  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
1006  {hor-mtm}) and (\ref{vertmtm}) in the (so-called) `vector invariant' form:  {hor-mtm}) and (\ref{vertmtm}) in the (so-called) `vector invariant' form:
1007    
1008  \begin{equation}  \begin{equation}
1009  \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}
1010  +\left( \nabla \times \vec{\mathbf{v}}\right) \times \vec{\mathbf{v}}+\nabla %  +\left( \nabla \times \vec{\mathbf{v}}\right) \times \vec{\mathbf{v}}+\nabla
1011  \left[ \frac{1}{2}(\vec{\mathbf{v}}\cdot \vec{\mathbf{v}})\right]  \left[ \frac{1}{2}(\vec{\mathbf{v}}\cdot \vec{\mathbf{v}})\right]
1012  \label{eq:vi-identity}  \label{eq:vi-identity}
1013  \end{equation}%  \end{equation}
1014  This permits alternative numerical treatments of the non-linear terms based  This permits alternative numerical treatments of the non-linear terms based
1015  on their representation as a vorticity flux. Because gradients of coordinate  on their representation as a vorticity flux. Because gradients of coordinate
1016  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
1017  representation of the metric terms in (\ref{eq:gu-speherical}), (\ref%  representation of the metric terms in (\ref{eq:gu-speherical}), (\ref
1018  {eq:gv-spherical}) and (\ref{eq:gw-spherical}), can be avoided: information  {eq:gv-spherical}) and (\ref{eq:gw-spherical}), can be avoided: information
1019  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
1020  to discretize the model.  to discretize the model.
1021    
1022  \subsection{Adjoint}  \subsection{Adjoint}
1023    
1024  Tangent linear and adoint counterparts of the forward model and described in  Tangent linear and adjoint counterparts of the forward model and described
1025  Chapter 5.  in Chapter 5.
1026    
1027  % $Header$  % $Header$
1028  % $Name$  % $Name$
# Line 1028  coordinates} Line 1036  coordinates}
1036    
1037  The hydrostatic primitive equations (HPEs) in p-coordinates are:  The hydrostatic primitive equations (HPEs) in p-coordinates are:
1038  \begin{eqnarray}  \begin{eqnarray}
1039  \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}}
1040  _{h}+\mathbf{\nabla }_{p}\phi  &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\mathbf{\nabla }_{p}\phi &=&\vec{\mathbf{\mathcal{F}}}
1041  \label{eq:atmos-mom} \\  \label{eq:atmos-mom} \\
1042  \frac{\partial \phi }{\partial p}+\alpha  &=&0  \label{eq-p-hydro-start} \\  \frac{\partial \phi }{\partial p}+\alpha &=&0  \label{eq-p-hydro-start} \\
1043  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{%  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1044  \partial p} &=&0  \label{eq:atmos-cont} \\  \partial p} &=&0  \label{eq:atmos-cont} \\
1045  p\alpha  &=&RT  \label{eq:atmos-eos} \\  p\alpha &=&RT  \label{eq:atmos-eos} \\
1046  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}
1047  \end{eqnarray}%  \end{eqnarray}
1048  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
1049  surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot  surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot
1050  \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total  \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total
1051  derivative, $f=2\Omega \sin lat$ is the Coriolis parameter, $\phi =gz$ is  derivative, $f=2\Omega \sin lat$ is the Coriolis parameter, $\phi =gz$ is
1052  the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp%  the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp
1053  }{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref%  }{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref
1054  {eq:atmos-heat}) is the first law of thermodynamics where internal energy $%  {eq:atmos-heat}) is the first law of thermodynamics where internal energy $
1055  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 $
1056  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.
1057    
1058  It is convenient to cast the heat equation in terms of potential temperature  It is convenient to cast the heat equation in terms of potential temperature
# Line 1052  $\theta $ so that it looks more like a g Line 1060  $\theta $ so that it looks more like a g
1060  Differentiating (\ref{eq:atmos-eos}) we get:  Differentiating (\ref{eq:atmos-eos}) we get:
1061  \begin{equation*}  \begin{equation*}
1062  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}
1063  \end{equation*}%  \end{equation*}
1064  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 $
1065  c_{p}=c_{v}+R$, gives:  c_{p}=c_{v}+R$, gives:
1066  \begin{equation}  \begin{equation}
1067  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}  c_{p}\frac{DT}{Dt}-\alpha \frac{Dp}{Dt}=\mathcal{Q}
1068  \label{eq-p-heat-interim}  \label{eq-p-heat-interim}
1069  \end{equation}%  \end{equation}
1070  Potential temperature is defined:  Potential temperature is defined:
1071  \begin{equation}  \begin{equation}
1072  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}  \theta =T(\frac{p_{c}}{p})^{\kappa }  \label{eq:potential-temp}
1073  \end{equation}%  \end{equation}
1074  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
1075  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:
1076  \begin{equation}  \begin{equation}
1077  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}  \Pi (p)=c_{p}(\frac{p}{p_{c}})^{\kappa }  \label{Exner}
1078  \end{equation}%  \end{equation}
1079  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
1080  the Exner function:  the Exner function:
1081  \begin{equation*}  \begin{equation*}
1082  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
1083  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{%  }{p}\;\;;\;\;\alpha =\frac{\kappa \Pi \theta }{p}=\frac{\partial \ \Pi }{
1084  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}%  \partial p}\theta \;\;;\;\;\frac{D\Pi }{Dt}=\frac{\partial \Pi }{\partial p}
1085  \frac{Dp}{Dt}  \frac{Dp}{Dt}
1086  \end{equation*}%  \end{equation*}
1087  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.  where $b=\frac{\partial \ \Pi }{\partial p}\theta $ is the buoyancy.
1088    
1089  The heat equation is obtained by noting that  The heat equation is obtained by noting that
1090  \begin{equation*}  \begin{equation*}
1091  c_{p}\frac{DT}{Dt}=\frac{D(\Pi \theta )}{Dt}=\Pi \frac{D\theta }{Dt}+\theta  c_{p}\frac{DT}{Dt}=\frac{D(\Pi \theta )}{Dt}=\Pi \frac{D\theta }{Dt}+\theta
1092  \frac{D\Pi }{Dt}=\Pi \frac{D\theta }{Dt}+\alpha \frac{Dp}{Dt}  \frac{D\Pi }{Dt}=\Pi \frac{D\theta }{Dt}+\alpha \frac{Dp}{Dt}
1093  \end{equation*}  \end{equation*}
1094  and on substituting into (\ref{eq-p-heat-interim}) gives:  and on substituting into (\ref{eq-p-heat-interim}) gives:
1095  \begin{equation}  \begin{equation}
# Line 1090  and on substituting into (\ref{eq-p-heat Line 1098  and on substituting into (\ref{eq-p-heat
1098  \end{equation}  \end{equation}
1099  which is in conservative form.  which is in conservative form.
1100    
1101  For convenience in the model we prefer to step forward (\ref%  For convenience in the model we prefer to step forward (\ref
1102  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).  {eq:potential-temperature-equation}) rather than (\ref{eq:atmos-heat}).
1103    
1104  \subsubsection{Boundary conditions}  \subsubsection{Boundary conditions}
# Line 1134  _{o}(p_{o})=g~Z_{topo}$, defined: Line 1142  _{o}(p_{o})=g~Z_{topo}$, defined:
1142    
1143  The final form of the HPE's in p coordinates is then:  The final form of the HPE's in p coordinates is then:
1144  \begin{eqnarray}  \begin{eqnarray}
1145  \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}}
1146  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \\
1147  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\  \frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\
1148  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{%  \mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{
1149  \partial p} &=&0 \\  \partial p} &=&0 \\
1150  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\  \frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\
1151  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }  \label{eq:atmos-prime}  \frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi }  \label{eq:atmos-prime}
# Line 1154  We review here the method by which the s Line 1162  We review here the method by which the s
1162  HPE's for the ocean written in z-coordinates are obtained. The  HPE's for the ocean written in z-coordinates are obtained. The
1163  non-Boussinesq equations for oceanic motion are:  non-Boussinesq equations for oceanic motion are:
1164  \begin{eqnarray}  \begin{eqnarray}
1165  \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}}
1166  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\
1167  \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}
1168  &=&\epsilon _{nh}\mathcal{F}_{w} \\  &=&\epsilon _{nh}\mathcal{F}_{w} \\
1169  \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}}
1170  _{h}+\frac{\partial w}{\partial z} &=&0 \\  _{h}+\frac{\partial w}{\partial z} &=&0 \\
1171  \rho  &=&\rho (\theta ,S,p) \\  \rho &=&\rho (\theta ,S,p) \\
1172  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\
1173  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:non-boussinesq}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:non-boussinesq}
1174  \end{eqnarray}%  \end{eqnarray}
1175  These equations permit acoustics modes, inertia-gravity waves,  These equations permit acoustics modes, inertia-gravity waves,
1176  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermo-haline  non-hydrostatic motions, a geostrophic (Rossby) mode and a thermo-haline
1177  mode. As written, they cannot be integrated forward consistently - if we  mode. As written, they cannot be integrated forward consistently - if we
1178  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
1179  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref%  consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref
1180  {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
1181  therefore necessary to manipulate the system as follows. Differentiating the  therefore necessary to manipulate the system as follows. Differentiating the
1182  EOS (equation of state) gives:  EOS (equation of state) gives:
# Line 1181  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexp Line 1189  _{\theta ,S}\frac{Dp}{Dt}  \label{EOSexp
1189  \end{equation}  \end{equation}
1190    
1191  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
1192  reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref%  reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref
1193  {eq-zns-cont} gives:  {eq-zns-cont} gives:
1194  \begin{equation}  \begin{equation}
1195  \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{
1196  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}  v}}+\partial _{z}w\approx 0  \label{eq-zns-pressure}
1197  \end{equation}  \end{equation}
1198  where we have used an approximation sign to indicate that we have assumed  where we have used an approximation sign to indicate that we have assumed
# Line 1192  adiabatic motion, dropping the $\frac{D\ Line 1200  adiabatic motion, dropping the $\frac{D\
1200  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
1201  can be explicitly integrated forward:  can be explicitly integrated forward:
1202  \begin{eqnarray}  \begin{eqnarray}
1203  \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}}
1204  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}}
1205  \label{eq-cns-hmom} \\  \label{eq-cns-hmom} \\
1206  \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}
1207  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\  &=&\epsilon _{nh}\mathcal{F}_{w}  \label{eq-cns-hydro} \\
1208  \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{
1209  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\  v}}_{h}+\frac{\partial w}{\partial z} &=&0  \label{eq-cns-cont} \\
1210  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-cns-eos} \\
1211  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-cns-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-cns-heat} \\
# Line 1211  wherever it appears in a product (ie. no Line 1219  wherever it appears in a product (ie. no
1219  `Boussinesq assumption'. The only term that then retains the full variation  `Boussinesq assumption'. The only term that then retains the full variation
1220  in $\rho $ is the gravitational acceleration:  in $\rho $ is the gravitational acceleration:
1221  \begin{eqnarray}  \begin{eqnarray}
1222  \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}}
1223  _{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}}}
1224  \label{eq-zcb-hmom} \\  \label{eq-zcb-hmom} \\
1225  \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}}
1226  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1227  \label{eq-zcb-hydro} \\  \label{eq-zcb-hydro} \\
1228  \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{
1229  \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} \\
1230  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\  \rho &=&\rho (\theta ,S,p)  \label{eq-zcb-eos} \\
1231  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zcb-heat} \\
1232  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq-zcb-salt}
1233  \end{eqnarray}  \end{eqnarray}
1234  These equations still retain acoustic modes. But, because the  These equations still retain acoustic modes. But, because the
1235  ``compressible'' terms are linearized, the pressure equation \ref%  ``compressible'' terms are linearized, the pressure equation \ref
1236  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent  {eq-zcb-cont} can be integrated implicitly with ease (the time-dependent
1237  term appears as a Helmholtz term in the non-hydrostatic pressure equation).  term appears as a Helmholtz term in the non-hydrostatic pressure equation).
1238  These are the \emph{truly} compressible Boussinesq equations. Note that the  These are the \emph{truly} compressible Boussinesq equations. Note that the
1239  EOS must have the same pressure dependency as the linearized pressure term,  EOS must have the same pressure dependency as the linearized pressure term,
1240  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{%  ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{
1241  c_{s}^{2}}$, for consistency.  c_{s}^{2}}$, for consistency.
1242    
1243  \subsubsection{`Anelastic' z-coordinate equations}  \subsubsection{`Anelastic' z-coordinate equations}
1244    
1245  The anelastic approximation filters the acoustic mode by removing the  The anelastic approximation filters the acoustic mode by removing the
1246  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}%  time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}
1247  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}%  ). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}
1248  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between  \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between
1249  continuity and EOS. A better solution is to change the dependency on  continuity and EOS. A better solution is to change the dependency on
1250  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
1251  height and a perturbation:  height and a perturbation:
1252  \begin{equation*}  \begin{equation*}
1253  \rho =\rho (\theta ,S,p_{o}(z)+\epsilon _{s}p^{\prime })  \rho =\rho (\theta ,S,p_{o}(z)+\epsilon _{s}p^{\prime })
1254  \end{equation*}  \end{equation*}
1255  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from  Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from
1256  differentiating the EOS, the continuity equation then becomes:  differentiating the EOS, the continuity equation then becomes:
1257  \begin{equation*}  \begin{equation*}
1258  \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{
1259  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+%  Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+
1260  \frac{\partial w}{\partial z}=0  \frac{\partial w}{\partial z}=0
1261  \end{equation*}  \end{equation*}
1262  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
1263  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},%  those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},
1264  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and  \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and
1265  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{%  $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{
1266  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta  Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta
1267  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon  ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon
1268  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation  _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation
1269  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
1270  anelastic continuity equation:  anelastic continuity equation:
1271  \begin{equation}  \begin{equation}
1272  \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}-
1273  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}  \frac{g}{c_{s}^{2}}w=0  \label{eq-za-cont1}
1274  \end{equation}  \end{equation}
1275  A slightly different route leads to the quasi-Boussinesq continuity equation  A slightly different route leads to the quasi-Boussinesq continuity equation
1276  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+%  where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+
1277  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }%  \mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }
1278  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:  _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding:
1279  \begin{equation}  \begin{equation}
1280  \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{
1281  \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}
1282  \end{equation}  \end{equation}
1283  Equations \ref{eq-za-cont1} and \ref{eq-za-cont2} are in fact the same  Equations \ref{eq-za-cont1} and \ref{eq-za-cont2} are in fact the same
# Line 1278  equation if: Line 1286  equation if:
1286  \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}}
1287  \end{equation}  \end{equation}
1288  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$  Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$
1289  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 $\frac{
1290  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The  g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The
1291  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are  full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are
1292  then:  then:
1293  \begin{eqnarray}  \begin{eqnarray}
1294  \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}}
1295  _{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}}}
1296  \label{eq-zab-hmom} \\  \label{eq-zab-hmom} \\
1297  \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}}
1298  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1299  \label{eq-zab-hydro} \\  \label{eq-zab-hydro} \\
1300  \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{
1301  \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} \\
1302  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\  \rho &=&\rho (\theta ,S,p_{o}(z))  \label{eq-zab-eos} \\
1303  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zab-heat} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq-zab-heat} \\
# Line 1302  Here, the objective is to drop the depth Line 1310  Here, the objective is to drop the depth
1310  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
1311  yield the ``truly'' incompressible Boussinesq equations:  yield the ``truly'' incompressible Boussinesq equations:
1312  \begin{eqnarray}  \begin{eqnarray}
1313  \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}}
1314  _{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}}}
1315  \label{eq-ztb-hmom} \\  \label{eq-ztb-hmom} \\
1316  \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}}
1317  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
1318  \label{eq-ztb-hydro} \\  \label{eq-ztb-hydro} \\
1319  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}  \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}
# Line 1324  retain compressibility effects in the de Line 1332  retain compressibility effects in the de
1332  density thus:  density thus:
1333  \begin{equation*}  \begin{equation*}
1334  \rho =\rho _{o}+\rho ^{\prime }  \rho =\rho _{o}+\rho ^{\prime }
1335  \end{equation*}%  \end{equation*}
1336  We then assert that variations with depth of $\rho _{o}$ are unimportant  We then assert that variations with depth of $\rho _{o}$ are unimportant
1337  while the compressible effects in $\rho ^{\prime }$ are:  while the compressible effects in $\rho ^{\prime }$ are:
1338  \begin{equation*}  \begin{equation*}
1339  \rho _{o}=\rho _{c}  \rho _{o}=\rho _{c}
1340  \end{equation*}%  \end{equation*}
1341  \begin{equation*}  \begin{equation*}
1342  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}  \rho ^{\prime }=\rho (\theta ,S,p_{o}(z))-\rho _{o}
1343  \end{equation*}%  \end{equation*}
1344  This then yields what we can call the semi-compressible Boussinesq  This then yields what we can call the semi-compressible Boussinesq
1345  equations:  equations:
1346  \begin{eqnarray}  \begin{eqnarray}
1347  \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}}
1348  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{%  _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{
1349  \mathcal{F}}}  \label{eq:ocean-mom} \\  \mathcal{F}}}  \label{eq:ocean-mom} \\
1350  \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
1351  _{c}}\frac{\partial p^{\prime }}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}  _{c}}\frac{\partial p^{\prime }}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}
# Line 1348  _{c}}\frac{\partial p^{\prime }}{\partia Line 1356  _{c}}\frac{\partial p^{\prime }}{\partia
1356  \\  \\
1357  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\  \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta }  \label{eq:ocean-theta} \\
1358  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}  \frac{DS}{Dt} &=&\mathcal{Q}_{s}  \label{eq:ocean-salt}
1359  \end{eqnarray}%  \end{eqnarray}
1360  Note that the hydrostatic pressure of the resting fluid, including that  Note that the hydrostatic pressure of the resting fluid, including that
1361  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
1362  dynamics.  dynamics.
# Line 1372  In spherical coordinates, the velocity c Line 1380  In spherical coordinates, the velocity c
1380  and vertical direction respectively, are given by (see Fig.2) :  and vertical direction respectively, are given by (see Fig.2) :
1381    
1382  \begin{equation*}  \begin{equation*}
1383  u=r\cos \phi \frac{D\lambda }{Dt}  u=r\cos \phi \frac{D\lambda }{Dt}
1384  \end{equation*}  \end{equation*}
1385    
1386  \begin{equation*}  \begin{equation*}
1387  v=r\frac{D\phi }{Dt}\qquad  v=r\frac{D\phi }{Dt}\qquad
1388  \end{equation*}  \end{equation*}
1389  $\qquad \qquad \qquad \qquad $  $\qquad \qquad \qquad \qquad $
1390    
1391  \begin{equation*}  \begin{equation*}
1392  \dot{r}=\frac{Dr}{Dt}  \dot{r}=\frac{Dr}{Dt}
1393  \end{equation*}  \end{equation*}
1394    
1395  Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial  Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial
# Line 1392  The `grad' ($\nabla $) and `div' ($\nabl Line 1400  The `grad' ($\nabla $) and `div' ($\nabl
1400  spherical coordinates:  spherical coordinates:
1401    
1402  \begin{equation*}  \begin{equation*}
1403  \nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda }%  \nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda }
1404  ,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r}%  ,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r}
1405  \right)  \right)
1406  \end{equation*}  \end{equation*}
1407    
1408  \begin{equation*}  \begin{equation*}
1409  \nabla .v\equiv \frac{1}{r\cos \phi }\left\{ \frac{\partial u}{\partial  \nabla .v\equiv \frac{1}{r\cos \phi }\left\{ \frac{\partial u}{\partial
1410  \lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\}  \lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\}
1411  +\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}
1412  \end{equation*}  \end{equation*}
1413    
1414  %%%% \end{document}  %tci%\end{document}

Legend:
Removed from v.1.1  
changed lines
  Added in v.1.4

  ViewVC Help
Powered by ViewVC 1.1.22