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revision 1.6 by cnh, Wed Oct 24 15:21:27 2001 UTC revision 1.12 by cnh, Mon Nov 19 14:33:44 2001 UTC
# Line 54  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  models - see fig \ref{fig:onemodel}
 \marginpar{  
 Fig.1 One model}\ref{fig:onemodel}  
58    
59  %% CNHbegin  %% CNHbegin
60  \input{part1/one_model_figure}  \input{part1/one_model_figure}
61  %% CNHend  %% 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  small-scale and large scale processes - see fig \ref{fig:all-scales}
 \marginpar{  
 Fig.2 All scales}\ref{fig:all-scales}  
65    
66  %% CNHbegin  %% CNHbegin
67  \input{part1/all_scales_figure}  \input{part1/all_scales_figure}
# Line 73  Fig.2 All scales}\ref{fig:all-scales} Line 69  Fig.2 All scales}\ref{fig:all-scales}
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  orthogonal curvilinear grids and shaved cells - see fig \ref{fig:finite-volumes}
 \marginpar{  
 Fig.3 Finite volumes}\ref{fig:finite-volumes}  
73    
74  %% CNHbegin  %% CNHbegin
75  \input{part1/fvol_figure}  \input{part1/fvol_figure}
# Line 89  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.
# Line 102  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:eddy_cs} 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 132  there are no mountains or land-sea contr Line 170  there are no mountains or land-sea contr
170  %% CNHend  %% 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  %% CNHbegin
185  \input{part1/hs_zave_u_figure}  \input{part1/hs_zave_u_figure}
# Line 157  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  %% CNHbegin
210  \input{part1/ocean_gyres_figure}  \input{part1/atl6_figure}
211  %% CNHend  %% 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 182  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  %%CNHbegin
229  \input{part1/global_circ_figure}  \input{part1/global_circ_figure}
# Line 195  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 214  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    
# Line 231  Forward and tangent linear counterparts Line 273  Forward and tangent linear counterparts
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.
# Line 248  yields sensitivities to all other model Line 292  yields sensitivities to all other model
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  %% CNHbegin
303  \input{part1/globes_figure}  \input{part1/globes_figure}
# Line 263  in-situ observations over the period 199 Line 308  in-situ observations over the period 199
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    telescoping to $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not shown).
316    
317  %%CNHbegin  %%CNHbegin
318  \input{part1/biogeo_figure}  \input{part1/biogeo_figure}
# Line 273  from a single year of a global, interann Line 320  from a single year of a global, interann
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  %%CNHbegin
# Line 293  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  %%CNHbegin
353  \input{part1/zandpcoord_figure.tex}  \input{part1/zandpcoord_figure.tex}
# Line 311  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  %%CNHbegin
367  \input{part1/vertcoord_figure.tex}  \input{part1/vertcoord_figure.tex}
# Line 322  Fig.5 The vertical coordinate of model}: Line 370  Fig.5 The vertical coordinate of model}:
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 410  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 425  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 447  where $\vec{\mathbf{n}}$ is the normal t Line 498  where $\vec{\mathbf{n}}$ is the normal t
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 518  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 555  w &=&\frac{D\eta }{Dt}\text{ at }r=R_{mo Line 606  w &=&\frac{D\eta }{Dt}\text{ at }r=R_{mo
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 568  Let us separate $\phi $ in to surface, h Line 620  Let us separate $\phi $ in to surface, h
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 661  In the above `${r}$' is the distance fro Line 713  In the above `${r}$' is the distance fro
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.
 \marginpar{  
 Fig.6 Spherical polar coordinate system.}  
716    
717  %%CNHbegin  %%CNHbegin
718  \input{part1/sphere_coord_figure.tex}  \input{part1/sphere_coord_figure.tex}
# Line 681  r $ in, for example, (\ref{eq:gu-speheri Line 731  r $ in, for example, (\ref{eq:gu-speheri
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 724  In the non-hydrostatic ocean model all t Line 775  In the non-hydrostatic ocean model all t
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 773  coordinates are supported - see eqs(\ref Line 824  coordinates are supported - see eqs(\ref
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 799  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 831  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}
# Line 857  r $. The above can be rearranged to yiel Line 908  r $. The above can be rearranged to yiel
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)
# Line 865  be written Line 916  be written
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{
# Line 904  tangential component of velocity, $v_{T} Line 955  tangential component of velocity, $v_{T}
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 944  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 952  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 1000  salinity ... ). Line 1051  salinity ... ).
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}
# Line 1018  to discretize the model. Line 1069  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 1140  _{o}(p_{o})=g~Z_{topo}$, defined: Line 1191  _{o}(p_{o})=g~Z_{topo}$, defined:
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 1164  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z} Line 1215  _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}
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    \label{eq:non-boussinesq}
1223  \end{eqnarray}  \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
# Line 1186  _{\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}

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