| 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} |
| 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} |
| 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 Eighth ECMWF Workshop on the Use of Parallel Processors |
| 123 |
|
in Meteorology, pages 406-425 |
| 124 |
|
World Scientific Publishing Co: UK |
| 125 |
|
|
| 126 |
|
Marotzke, J, Giering,R., Zhang, K.Q., Stammer,D., Hill,C., and T.Lee, (1999) |
| 127 |
|
Construction of the adjoint MIT ocean general circulation model and |
| 128 |
|
application to Atlantic heat transport variability |
| 129 |
|
J. Geophysical Res., 104(C12), 29,529-29,547. |
| 130 |
|
|
| 131 |
|
|
| 132 |
|
\end{verbatim} |
| 133 |
|
|
| 134 |
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 |
| 135 |
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. |
| 141 |
|
|
| 142 |
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, |
| 143 |
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 |
| 144 |
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 |
| 145 |
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 |
| 146 |
of them here. A more detailed description of the underlying formulation, |
of them here. A more detailed description of the underlying formulation, |
| 147 |
numerical algorithm and implementation that lie behind these calculations is |
numerical algorithm and implementation that lie behind these calculations is |
| 148 |
given later. Indeed many of the illustrative examples shown below can be |
given later. Indeed many of the illustrative examples shown below can be |
| 149 |
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 |
| 150 |
running linux, together with a FORTRAN\ 77 compiler) and follow the examples |
running Linux, together with a FORTRAN\ 77 compiler) and follow the examples |
| 151 |
described in detail in the documentation. |
described in detail in the documentation. |
| 152 |
|
|
| 153 |
\subsection{Global atmosphere: `Held-Suarez' benchmark} |
\subsection{Global atmosphere: `Held-Suarez' benchmark} |
| 154 |
|
|
| 155 |
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, |
| 156 |
oceanographic flows at both small and large scales. |
both atmospheric and oceanographic flows at both small and large scales. |
| 157 |
|
|
| 158 |
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$mb$ |
| 159 |
temperature field obtained using the atmospheric isomorph of MITgcm run at |
temperature field obtained using the atmospheric isomorph of MITgcm run at |
| 160 |
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 |
| 161 |
(blue) and warm air along an equatorial band (red). Fully developed |
(blue) and warm air along an equatorial band (red). Fully developed |
| 171 |
%% CNHend |
%% CNHend |
| 172 |
|
|
| 173 |
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 |
| 174 |
globe permitting a uniform gridding and obviated the need to fourier filter. |
globe permitting a uniform griding and obviated the need to Fourier filter. |
| 175 |
The `vector-invariant' form of MITgcm supports any orthogonal curvilinear |
The `vector-invariant' form of MITgcm supports any orthogonal curvilinear |
| 176 |
grid, of which the cubed sphere is just one of many choices. |
grid, of which the cubed sphere is just one of many choices. |
| 177 |
|
|
| 178 |
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 |
| 179 |
wind and meridional overturning streamfunction from a 20-level version of |
wind from a 20-level configuration of |
| 180 |
the model. It compares favorable with more conventional spatial |
the model. It compares favorable with more conventional spatial |
| 181 |
discretization approaches. |
discretization approaches. The two plots show the field calculated using the |
| 182 |
|
cube-sphere grid and the flow calculated using a regular, spherical polar |
| 183 |
A regular spherical lat-lon grid can also be used. |
latitude-longitude grid. Both grids are supported within the model. |
| 184 |
|
|
| 185 |
%% CNHbegin |
%% CNHbegin |
| 186 |
\input{part1/hs_zave_u_figure} |
\input{part1/hs_zave_u_figure} |
| 196 |
increased until the baroclinic instability process is resolved, numerical |
increased until the baroclinic instability process is resolved, numerical |
| 197 |
solutions of a different and much more realistic kind, can be obtained. |
solutions of a different and much more realistic kind, can be obtained. |
| 198 |
|
|
| 199 |
Fig. ?.? shows the surface temperature and velocity field obtained from |
Figure \ref{fig:ocean-gyres} shows the surface temperature and velocity |
| 200 |
MITgcm run at $\frac{1}{6}^{\circ }$ horizontal resolution on a $lat-lon$ |
field obtained from MITgcm run at $\frac{1}{6}^{\circ }$ horizontal |
| 201 |
|
resolution on a $lat-lon$ |
| 202 |
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 |
| 203 |
(to avoid the converging of meridian in northern latitudes). 21 vertical |
(to avoid the converging of meridian in northern latitudes). 21 vertical |
| 204 |
levels are used in the vertical with a `lopped cell' representation of |
levels are used in the vertical with a `lopped cell' representation of |
| 205 |
topography. The development and propagation of anomalously warm and cold |
topography. The development and propagation of anomalously warm and cold |
| 206 |
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 |
| 207 |
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 |
| 208 |
visible. |
visible. |
| 209 |
|
|
| 210 |
%% CNHbegin |
%% CNHbegin |
| 211 |
\input{part1/ocean_gyres_figure} |
\input{part1/atl6_figure} |
| 212 |
%% CNHend |
%% CNHend |
| 213 |
|
|
| 214 |
|
|
| 215 |
\subsection{Global ocean circulation} |
\subsection{Global ocean circulation} |
| 216 |
|
|
| 217 |
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 |
| 218 |
|
the surface of a 4$^{\circ }$ |
| 219 |
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 |
| 220 |
represent topography on a regular $lat-lon$ grid extending from 70$^{\circ |
represent topography on a regular $lat-lon$ grid extending from 70$^{\circ |
| 221 |
}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 |
| 223 |
transfer properties of ocean eddies, convection and mixing is parameterized |
transfer properties of ocean eddies, convection and mixing is parameterized |
| 224 |
in this model. |
in this model. |
| 225 |
|
|
| 226 |
Fig.E2b shows the meridional overturning circulation of the global ocean in |
Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning |
| 227 |
Sverdrups. |
circulation of the global ocean in Sverdrups. |
| 228 |
|
|
| 229 |
%%CNHbegin |
%%CNHbegin |
| 230 |
\input{part1/global_circ_figure} |
\input{part1/global_circ_figure} |
| 236 |
ocean may be influenced by rotation when the deformation radius is smaller |
ocean may be influenced by rotation when the deformation radius is smaller |
| 237 |
than the width of the cooling region. Rather than gravity plumes, the |
than the width of the cooling region. Rather than gravity plumes, the |
| 238 |
mechanism for moving dense fluid down the shelf is then through geostrophic |
mechanism for moving dense fluid down the shelf is then through geostrophic |
| 239 |
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} |
| 240 |
|
(blue is cold dense fluid, red is |
| 241 |
warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to |
warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to |
| 242 |
trigger convection by surface cooling. The cold, dense water falls down the |
trigger convection by surface cooling. The cold, dense water falls down the |
| 243 |
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 |
| 256 |
dynamics and mixing in oceanic canyons and ridges driven by large amplitude |
dynamics and mixing in oceanic canyons and ridges driven by large amplitude |
| 257 |
barotropic tidal currents imposed through open boundary conditions. |
barotropic tidal currents imposed through open boundary conditions. |
| 258 |
|
|
| 259 |
Fig. ?.? shows the influence of cross-slope topographic variations on |
Fig. \ref{fig:boundary-forced-wave} shows the influence of cross-slope |
| 260 |
|
topographic variations on |
| 261 |
internal wave breaking - the cross-slope velocity is in color, the density |
internal wave breaking - the cross-slope velocity is in color, the density |
| 262 |
contoured. The internal waves are excited by application of open boundary |
contoured. The internal waves are excited by application of open boundary |
| 263 |
conditions on the left.\ They propagate to the sloping boundary (represented |
conditions on the left. They propagate to the sloping boundary (represented |
| 264 |
using MITgcm's finite volume spatial discretization) where they break under |
using MITgcm's finite volume spatial discretization) where they break under |
| 265 |
nonhydrostatic dynamics. |
nonhydrostatic dynamics. |
| 266 |
|
|
| 274 |
`automatic adjoint compiler'. These can be used in parameter sensitivity and |
`automatic adjoint compiler'. These can be used in parameter sensitivity and |
| 275 |
data assimilation studies. |
data assimilation studies. |
| 276 |
|
|
| 277 |
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} |
| 278 |
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 |
| 279 |
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} |
| 280 |
\mathcal{H}$ is the air-sea heat flux 100 years before. We see that $J$ is |
at 60$^{\circ }$N and $ |
| 281 |
|
\mathcal{H}(\lambda,\varphi)$ is the mean, local air-sea heat flux over |
| 282 |
|
a 100 year period. We see that $J$ is |
| 283 |
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 |
| 284 |
of deep water for the thermohaline circulations. This calculation also |
of deep water for the thermohaline circulations. This calculation also |
| 285 |
yields sensitivities to all other model parameters. |
yields sensitivities to all other model parameters. |
| 293 |
An important application of MITgcm is in state estimation of the global |
An important application of MITgcm is in state estimation of the global |
| 294 |
ocean circulation. An appropriately defined `cost function', which measures |
ocean circulation. An appropriately defined `cost function', which measures |
| 295 |
the departure of the model from observations (both remotely sensed and |
the departure of the model from observations (both remotely sensed and |
| 296 |
insitu) over an interval of time, is minimized by adjusting `control |
in-situ) over an interval of time, is minimized by adjusting `control |
| 297 |
parameters' such as air-sea fluxes, the wind field, the initial conditions |
parameters' such as air-sea fluxes, the wind field, the initial conditions |
| 298 |
etc. Figure ?.? shows an estimate of the time-mean surface elevation of the |
etc. Figure \ref{fig:assimilated-globes} shows the large scale planetary |
| 299 |
ocean obtained by bringing the model in to consistency with altimetric and |
circulation and a Hopf-Muller plot of Equatorial sea-surface height. |
| 300 |
in-situ observations over the period 1992-1997. |
Both are obtained from assimilation bringing the model in to |
| 301 |
|
consistency with altimetric and in-situ observations over the period |
| 302 |
|
1992-1997. |
| 303 |
|
|
| 304 |
%% CNHbegin |
%% CNHbegin |
| 305 |
\input{part1/globes_figure} |
\input{part1/assim_figure} |
| 306 |
%% CNHend |
%% CNHend |
| 307 |
|
|
| 308 |
\subsection{Ocean biogeochemical cycles} |
\subsection{Ocean biogeochemical cycles} |
| 310 |
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 |
| 311 |
example one can study the effects of interannual changes in meteorological |
example one can study the effects of interannual changes in meteorological |
| 312 |
forcing and upper ocean circulation on the fluxes of carbon dioxide and |
forcing and upper ocean circulation on the fluxes of carbon dioxide and |
| 313 |
oxygen between the ocean and atmosphere. The figure shows the annual air-sea |
oxygen between the ocean and atmosphere. Figure \ref{fig:biogeo} shows |
| 314 |
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 |
| 315 |
from a single year of a global, interannually varying simulation. |
the southern oceans from a single year of a global, interannually varying |
| 316 |
|
simulation. The simulation is run at $1^{\circ}\times1^{\circ}$ resolution |
| 317 |
|
telescoping to $\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not shown). |
| 318 |
|
|
| 319 |
%%CNHbegin |
%%CNHbegin |
| 320 |
\input{part1/biogeo_figure} |
\input{part1/biogeo_figure} |
| 322 |
|
|
| 323 |
\subsection{Simulations of laboratory experiments} |
\subsection{Simulations of laboratory experiments} |
| 324 |
|
|
| 325 |
Figure ?.? shows MITgcm being used to simulate a laboratory experiment |
Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a |
| 326 |
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 |
| 327 |
initially homogeneous tank of water ($1m$ in diameter) is driven from its |
initially homogeneous tank of water ($1m$ in diameter) is driven from its |
| 328 |
free surface by a rotating heated disk. The combined action of mechanical |
free surface by a rotating heated disk. The combined action of mechanical |
| 329 |
and thermal forcing creates a lens of fluid which becomes baroclinically |
and thermal forcing creates a lens of fluid which becomes baroclinically |
| 330 |
unstable. The stratification and depth of penetration of the lens is |
unstable. The stratification and depth of penetration of the lens is |
| 331 |
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 |
| 332 |
stratification of the ACC. |
stratification of the ACC. |
| 333 |
|
|
| 334 |
%%CNHbegin |
%%CNHbegin |
| 342 |
|
|
| 343 |
To render atmosphere and ocean models from one dynamical core we exploit |
To render atmosphere and ocean models from one dynamical core we exploit |
| 344 |
`isomorphisms' between equation sets that govern the evolution of the |
`isomorphisms' between equation sets that govern the evolution of the |
| 345 |
respective fluids - see fig.4 |
respective fluids - see figure \ref{fig:isomorphic-equations}. |
| 346 |
\marginpar{ |
One system of hydrodynamical equations is written down |
|
Fig.4. Isomorphisms}. One system of hydrodynamical equations is written down |
|
| 347 |
and encoded. The model variables have different interpretations depending on |
and encoded. The model variables have different interpretations depending on |
| 348 |
whether the atmosphere or ocean is being studied. Thus, for example, the |
whether the atmosphere or ocean is being studied. Thus, for example, the |
| 349 |
vertical coordinate `$r$' is interpreted as pressure, $p$, if we are |
vertical coordinate `$r$' is interpreted as pressure, $p$, if we are |
| 350 |
modeling the atmosphere and height, $z$, if we are modeling the ocean. |
modeling the atmosphere (left hand side of figure \ref{fig:isomorphic-equations}) |
| 351 |
|
and height, $z$, if we are modeling the ocean (right hand side of figure |
| 352 |
|
\ref{fig:isomorphic-equations}). |
| 353 |
|
|
| 354 |
%%CNHbegin |
%%CNHbegin |
| 355 |
\input{part1/zandpcoord_figure.tex} |
\input{part1/zandpcoord_figure.tex} |
| 361 |
depend on $\theta $, $S$, and $p$. The equations that govern the evolution |
depend on $\theta $, $S$, and $p$. The equations that govern the evolution |
| 362 |
of these fields, obtained by applying the laws of classical mechanics and |
of these fields, obtained by applying the laws of classical mechanics and |
| 363 |
thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of |
thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of |
| 364 |
a generic vertical coordinate, $r$, see fig.5 |
a generic vertical coordinate, $r$, so that the appropriate |
| 365 |
\marginpar{ |
kinematic boundary conditions can be applied isomorphically |
| 366 |
Fig.5 The vertical coordinate of model}: |
see figure \ref{fig:zandp-vert-coord}. |
| 367 |
|
|
| 368 |
%%CNHbegin |
%%CNHbegin |
| 369 |
\input{part1/vertcoord_figure.tex} |
\input{part1/vertcoord_figure.tex} |
| 372 |
\begin{equation*} |
\begin{equation*} |
| 373 |
\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}} |
| 374 |
\right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}} |
\right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}} |
| 375 |
\text{ horizontal mtm} |
\text{ horizontal mtm} \label{eq:horizontal_mtm} |
| 376 |
\end{equation*} |
\end{equation*} |
| 377 |
|
|
| 378 |
\begin{equation*} |
\begin{equation} |
| 379 |
\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{ |
| 380 |
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{ |
| 381 |
vertical mtm} |
vertical mtm} \label{eq:vertical_mtm} |
| 382 |
\end{equation*} |
\end{equation} |
| 383 |
|
|
| 384 |
\begin{equation} |
\begin{equation} |
| 385 |
\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{ |
\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{ |
| 386 |
\partial r}=0\text{ continuity} \label{eq:continuous} |
\partial r}=0\text{ continuity} \label{eq:continuity} |
| 387 |
\end{equation} |
\end{equation} |
| 388 |
|
|
| 389 |
\begin{equation*} |
\begin{equation} |
| 390 |
b=b(\theta ,S,r)\text{ equation of state} |
b=b(\theta ,S,r)\text{ equation of state} \label{eq:equation_of_state} |
| 391 |
\end{equation*} |
\end{equation} |
| 392 |
|
|
| 393 |
\begin{equation*} |
\begin{equation} |
| 394 |
\frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature} |
\frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature} |
| 395 |
\end{equation*} |
\label{eq:potential_temperature} |
| 396 |
|
\end{equation} |
| 397 |
|
|
| 398 |
\begin{equation*} |
\begin{equation} |
| 399 |
\frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity} |
\frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity} |
| 400 |
\end{equation*} |
\label{eq:humidity_salt} |
| 401 |
|
\end{equation} |
| 402 |
|
|
| 403 |
Here: |
Here: |
| 404 |
|
|
| 462 |
\end{equation*} |
\end{equation*} |
| 463 |
|
|
| 464 |
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 |
| 465 |
extensive `physics' packages for atmosphere and ocean described in Chapter 6. |
`physics' and forcing packages for atmosphere and ocean. These are described |
| 466 |
|
in later chapters. |
| 467 |
|
|
| 468 |
\subsection{Kinematic Boundary conditions} |
\subsection{Kinematic Boundary conditions} |
| 469 |
|
|
| 470 |
\subsubsection{vertical} |
\subsubsection{vertical} |
| 471 |
|
|
| 472 |
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}): |
| 473 |
|
|
| 474 |
\begin{equation} |
\begin{equation} |
| 475 |
\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)} |
| 478 |
|
|
| 479 |
\begin{equation} |
\begin{equation} |
| 480 |
\dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \ |
\dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \ |
| 481 |
(oceansurface,bottomoftheatmosphere)} \label{eq:movingbc} |
(ocean surface,bottom of the atmosphere)} \label{eq:movingbc} |
| 482 |
\end{equation} |
\end{equation} |
| 483 |
|
|
| 484 |
Here |
Here |
| 500 |
|
|
| 501 |
\subsection{Atmosphere} |
\subsection{Atmosphere} |
| 502 |
|
|
| 503 |
In the atmosphere, see fig.5, we interpret: |
In the atmosphere, (see figure \ref{fig:zandp-vert-coord}), we interpret: |
| 504 |
|
|
| 505 |
\begin{equation} |
\begin{equation} |
| 506 |
r=p\text{ is the pressure} \label{eq:atmos-r} |
r=p\text{ is the pressure} \label{eq:atmos-r} |
| 571 |
atmosphere)} \label{eq:moving-bc-atmos} |
atmosphere)} \label{eq:moving-bc-atmos} |
| 572 |
\end{eqnarray} |
\end{eqnarray} |
| 573 |
|
|
| 574 |
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}) |
| 575 |
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 $p$ |
| 576 |
coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}). |
coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}). |
| 577 |
|
|
| 578 |
\subsection{Ocean} |
\subsection{Ocean} |
| 608 |
\end{eqnarray} |
\end{eqnarray} |
| 609 |
where $\eta $ is the elevation of the free surface. |
where $\eta $ is the elevation of the free surface. |
| 610 |
|
|
| 611 |
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 |
| 612 |
|
of oceanic equations |
| 613 |
which, for convenience, are written out in $z$ coordinates in Appendix Ocean |
which, for convenience, are written out in $z$ coordinates in Appendix Ocean |
| 614 |
- see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}). |
- see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}). |
| 615 |
|
|
| 622 |
\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) |
| 623 |
\label{eq:phi-split} |
\label{eq:phi-split} |
| 624 |
\end{equation} |
\end{equation} |
| 625 |
and write eq(\ref{incompressible}a,b) in the form: |
and write eq(\ref{eq:incompressible}) in the form: |
| 626 |
|
|
| 627 |
\begin{equation} |
\begin{equation} |
| 628 |
\frac{\partial \vec{\mathbf{v}_{h}}}{\partial t}+\mathbf{\nabla }_{h}\phi |
\frac{\partial \vec{\mathbf{v}_{h}}}{\partial t}+\mathbf{\nabla }_{h}\phi |
| 655 |
\left. |
\left. |
| 656 |
\begin{tabular}{l} |
\begin{tabular}{l} |
| 657 |
$G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\ |
$G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\ |
| 658 |
$-\left\{ \underline{\frac{u\dot{r}}{{r}}}-\frac{uv\tan lat}{{r}}\right\} $ |
$-\left\{ \underline{\frac{u\dot{r}}{{r}}}-\frac{uv\tan \varphi}{{r}}\right\} $ |
| 659 |
\\ |
\\ |
| 660 |
$-\left\{ -2\Omega v\sin lat+\underline{2\Omega \dot{r}\cos lat}\right\} $ |
$-\left\{ -2\Omega v\sin \varphi+\underline{2\Omega \dot{r}\cos \varphi}\right\} $ |
| 661 |
\\ |
\\ |
| 662 |
$+\mathcal{F}_{u}$ |
$+\mathcal{F}_{u}$ |
| 663 |
\end{tabular} |
\end{tabular} |
| 675 |
\left. |
\left. |
| 676 |
\begin{tabular}{l} |
\begin{tabular}{l} |
| 677 |
$G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\ |
$G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\ |
| 678 |
$-\left\{ \underline{\frac{v\dot{r}}{{r}}}-\frac{u^{2}\tan lat}{{r}}\right\} |
$-\left\{ \underline{\frac{v\dot{r}}{{r}}}-\frac{u^{2}\tan \varphi}{{r}}\right\} |
| 679 |
$ \\ |
$ \\ |
| 680 |
$-\left\{ -2\Omega u\sin lat\right\} $ \\ |
$-\left\{ -2\Omega u\sin \varphi \right\} $ \\ |
| 681 |
$+\mathcal{F}_{v}$ |
$+\mathcal{F}_{v}$ |
| 682 |
\end{tabular} |
\end{tabular} |
| 683 |
\ \right\} \left\{ |
\ \right\} \left\{ |
| 696 |
\begin{tabular}{l} |
\begin{tabular}{l} |
| 697 |
$G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\ |
$G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\ |
| 698 |
$+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\ |
$+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\ |
| 699 |
${+}\underline{{2\Omega u\cos lat}}$ \\ |
${+}\underline{{2\Omega u\cos \varphi}}$ \\ |
| 700 |
$\underline{\underline{\mathcal{F}_{\dot{r}}}}$ |
$\underline{\underline{\mathcal{F}_{\dot{r}}}}$ |
| 701 |
\end{tabular} |
\end{tabular} |
| 702 |
\ \right\} \left\{ |
\ \right\} \left\{ |
| 710 |
\end{equation} |
\end{equation} |
| 711 |
\qquad \qquad \qquad \qquad \qquad |
\qquad \qquad \qquad \qquad \qquad |
| 712 |
|
|
| 713 |
In the above `${r}$' is the distance from the center of the earth and `$lat$ |
In the above `${r}$' is the distance from the center of the earth and `$\varphi$ |
| 714 |
' is latitude. |
' is latitude. |
| 715 |
|
|
| 716 |
Grad and div operators in spherical coordinates are defined in appendix |
Grad and div operators in spherical coordinates are defined in appendix |
| 717 |
OPERATORS. |
OPERATORS. |
|
\marginpar{ |
|
|
Fig.6 Spherical polar coordinate system.} |
|
| 718 |
|
|
| 719 |
%%CNHbegin |
%%CNHbegin |
| 720 |
\input{part1/sphere_coord_figure.tex} |
\input{part1/sphere_coord_figure.tex} |
| 733 |
the radius of the earth. |
the radius of the earth. |
| 734 |
|
|
| 735 |
\subsubsection{Hydrostatic and quasi-hydrostatic forms} |
\subsubsection{Hydrostatic and quasi-hydrostatic forms} |
| 736 |
|
\label{sec:hydrostatic_and_quasi-hydrostatic_forms} |
| 737 |
|
|
| 738 |
These are discussed at length in Marshall et al (1997a). |
These are discussed at length in Marshall et al (1997a). |
| 739 |
|
|
| 747 |
|
|
| 748 |
In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between |
In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between |
| 749 |
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 |
| 750 |
\phi $ Coriolis term are not neglected and are balanced by a non-hydrostatic |
\varphi $ Coriolis term are not neglected and are balanced by a non-hydrostatic |
| 751 |
contribution to the pressure field: only the terms underlined twice in Eqs. ( |
contribution to the pressure field: only the terms underlined twice in Eqs. ( |
| 752 |
\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 |
| 753 |
and, simultaneously, the shallow atmosphere approximation is relaxed. In |
and, simultaneously, the shallow atmosphere approximation is relaxed. In |
| 756 |
vertical momentum equation (\ref{eq:mom-w}) becomes: |
vertical momentum equation (\ref{eq:mom-w}) becomes: |
| 757 |
|
|
| 758 |
\begin{equation*} |
\begin{equation*} |
| 759 |
\frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat |
\frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos \varphi |
| 760 |
\end{equation*} |
\end{equation*} |
| 761 |
making a small correction to the hydrostatic pressure. |
making a small correction to the hydrostatic pressure. |
| 762 |
|
|
| 777 |
three dimensional elliptic equation must be solved subject to Neumann |
three dimensional elliptic equation must be solved subject to Neumann |
| 778 |
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 |
| 779 |
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 |
| 780 |
incompressible condition eq(\ref{eq:continuous})c has already filtered out |
incompressible condition eq(\ref{eq:continuity}) has already filtered out |
| 781 |
acoustic modes. It does, however, ensure that the gravity waves are treated |
acoustic modes. It does, however, ensure that the gravity waves are treated |
| 782 |
accurately with an exact dispersion relation. The \textbf{NH} set has a |
accurately with an exact dispersion relation. The \textbf{NH} set has a |
| 783 |
complete angular momentum principle and consistent energetics - see White |
complete angular momentum principle and consistent energetics - see White |
| 826 |
\subsection{Solution strategy} |
\subsection{Solution strategy} |
| 827 |
|
|
| 828 |
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{ |
| 829 |
NH} models is summarized in Fig.7. |
NH} models is summarized in Figure \ref{fig:solution-strategy}. |
| 830 |
\marginpar{ |
Under all dynamics, a 2-d elliptic equation is |
|
Fig.7 Solution strategy} Under all dynamics, a 2-d elliptic equation is |
|
| 831 |
first solved to find the surface pressure and the hydrostatic pressure at |
first solved to find the surface pressure and the hydrostatic pressure at |
| 832 |
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 |
| 833 |
\textbf{QH} dynamics, the horizontal momentum equations are then stepped |
\textbf{QH} dynamics, the horizontal momentum equations are then stepped |
| 841 |
%%CNHend |
%%CNHend |
| 842 |
|
|
| 843 |
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 |
| 844 |
course, some complication that goes with the inclusion of $\cos \phi \ $ |
course, some complication that goes with the inclusion of $\cos \varphi \ $ |
| 845 |
Coriolis terms and the relaxation of the shallow atmosphere approximation. |
Coriolis terms and the relaxation of the shallow atmosphere approximation. |
| 846 |
But this leads to negligible increase in computation. In \textbf{NH}, in |
But this leads to negligible increase in computation. In \textbf{NH}, in |
| 847 |
contrast, one additional elliptic equation - a three-dimensional one - must |
contrast, one additional elliptic equation - a three-dimensional one - must |
| 851 |
hydrostatic limit, is as computationally economic as the \textbf{HPEs}. |
hydrostatic limit, is as computationally economic as the \textbf{HPEs}. |
| 852 |
|
|
| 853 |
\subsection{Finding the pressure field} |
\subsection{Finding the pressure field} |
| 854 |
|
\label{sec:finding_the_pressure_field} |
| 855 |
|
|
| 856 |
Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the |
Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the |
| 857 |
pressure field must be obtained diagnostically. We proceed, as before, by |
pressure field must be obtained diagnostically. We proceed, as before, by |
| 884 |
|
|
| 885 |
\subsubsection{Surface pressure} |
\subsubsection{Surface pressure} |
| 886 |
|
|
| 887 |
The surface pressure equation can be obtained by integrating continuity, ( |
The surface pressure equation can be obtained by integrating continuity, |
| 888 |
\ref{eq:continuous})c, vertically from $r=R_{fixed}$ to $r=R_{moving}$ |
(\ref{eq:continuity}), vertically from $r=R_{fixed}$ to $r=R_{moving}$ |
| 889 |
|
|
| 890 |
\begin{equation*} |
\begin{equation*} |
| 891 |
\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} |
| 910 |
where we have incorporated a source term. |
where we have incorporated a source term. |
| 911 |
|
|
| 912 |
Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential |
Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential |
| 913 |
(atmospheric model), in (\ref{mtm-split}), the horizontal gradient term can |
(atmospheric model), in (\ref{eq:mom-h}), the horizontal gradient term can |
| 914 |
be written |
be written |
| 915 |
\begin{equation} |
\begin{equation} |
| 916 |
\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) |
| 918 |
\end{equation} |
\end{equation} |
| 919 |
where $b_{s}$ is the buoyancy at the surface. |
where $b_{s}$ is the buoyancy at the surface. |
| 920 |
|
|
| 921 |
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 |
| 922 |
{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 |
| 923 |
elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free |
elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free |
| 924 |
surface' and `rigid lid' approaches are available. |
surface' and `rigid lid' approaches are available. |
| 925 |
|
|
| 926 |
\subsubsection{Non-hydrostatic pressure} |
\subsubsection{Non-hydrostatic pressure} |
| 927 |
|
|
| 928 |
Taking the horizontal divergence of (\ref{hor-mtm}) and adding $\frac{ |
Taking the horizontal divergence of (\ref{eq:mom-h}) and adding |
| 929 |
\partial }{\partial r}$ of (\ref{vertmtm}), invoking the continuity equation |
$\frac{\partial }{\partial r}$ of (\ref{eq:mom-w}), invoking the continuity equation |
| 930 |
(\ref{incompressible}), we deduce that: |
(\ref{eq:continuity}), we deduce that: |
| 931 |
|
|
| 932 |
\begin{equation} |
\begin{equation} |
| 933 |
\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{ |
| 957 |
depending on the form chosen for the dissipative terms in the momentum |
depending on the form chosen for the dissipative terms in the momentum |
| 958 |
equations - see below. |
equations - see below. |
| 959 |
|
|
| 960 |
Eq.(\ref{nonormalflow}) implies, making use of (\ref{mtm-split}), that: |
Eq.(\ref{nonormalflow}) implies, making use of (\ref{eq:mom-h}), that: |
| 961 |
|
|
| 962 |
\begin{equation} |
\begin{equation} |
| 963 |
\widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}} |
\widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}} |
| 997 |
converges rapidly because $\phi _{nh}\ $is then only a small correction to |
converges rapidly because $\phi _{nh}\ $is then only a small correction to |
| 998 |
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). |
| 999 |
|
|
| 1000 |
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}) |
| 1001 |
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. |
| 1002 |
|
|
| 1003 |
\subsection{Forcing/dissipation} |
\subsection{Forcing/dissipation} |
| 1005 |
\subsubsection{Forcing} |
\subsubsection{Forcing} |
| 1006 |
|
|
| 1007 |
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 |
| 1008 |
`physics packages' described in detail in chapter ??. |
`physics packages' and forcing packages. These are described later on. |
| 1009 |
|
|
| 1010 |
\subsubsection{Dissipation} |
\subsubsection{Dissipation} |
| 1011 |
|
|
| 1053 |
\subsection{Vector invariant form} |
\subsection{Vector invariant form} |
| 1054 |
|
|
| 1055 |
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 |
| 1056 |
{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: |
| 1057 |
|
|
| 1058 |
\begin{equation} |
\begin{equation} |
| 1059 |
\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} |
| 1071 |
|
|
| 1072 |
\subsection{Adjoint} |
\subsection{Adjoint} |
| 1073 |
|
|
| 1074 |
Tangent linear and adjoint counterparts of the forward model and described |
Tangent linear and adjoint counterparts of the forward model are described |
| 1075 |
in Chapter 5. |
in Chapter 5. |
| 1076 |
|
|
| 1077 |
% $Header$ |
% $Header$ |
| 1098 |
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 |
| 1099 |
surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot |
surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot |
| 1100 |
\mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total |
\mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total |
| 1101 |
derivative, $f=2\Omega \sin lat$ is the Coriolis parameter, $\phi =gz$ is |
derivative, $f=2\Omega \sin \varphi$ is the Coriolis parameter, $\phi =gz$ is |
| 1102 |
the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp |
the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp |
| 1103 |
}{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref |
}{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref |
| 1104 |
{eq:atmos-heat}) is the first law of thermodynamics where internal energy $ |
{eq:atmos-heat}) is the first law of thermodynamics where internal energy $ |
| 1193 |
The final form of the HPE's in p coordinates is then: |
The final form of the HPE's in p coordinates is then: |
| 1194 |
\begin{eqnarray} |
\begin{eqnarray} |
| 1195 |
\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}} |
| 1196 |
_{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \\ |
_{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \label{eq:atmos-prime} \\ |
| 1197 |
\frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\ |
\frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\ |
| 1198 |
\mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{ |
\mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{ |
| 1199 |
\partial p} &=&0 \\ |
\partial p} &=&0 \\ |
| 1200 |
\frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\ |
\frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\ |
| 1201 |
\frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi } \label{eq:atmos-prime} |
\frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi } |
| 1202 |
\end{eqnarray} |
\end{eqnarray} |
| 1203 |
|
|
| 1204 |
% $Header$ |
% $Header$ |
| 1217 |
\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} |
| 1218 |
&=&\epsilon _{nh}\mathcal{F}_{w} \\ |
&=&\epsilon _{nh}\mathcal{F}_{w} \\ |
| 1219 |
\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}} |
| 1220 |
_{h}+\frac{\partial w}{\partial z} &=&0 \\ |
_{h}+\frac{\partial w}{\partial z} &=&0 \label{eq-zns-cont}\\ |
| 1221 |
\rho &=&\rho (\theta ,S,p) \\ |
\rho &=&\rho (\theta ,S,p) \label{eq-zns-eos}\\ |
| 1222 |
\frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\ |
\frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-zns-heat}\\ |
| 1223 |
\frac{DS}{Dt} &=&\mathcal{Q}_{s} \label{eq:non-boussinesq} |
\frac{DS}{Dt} &=&\mathcal{Q}_{s} \label{eq-zns-salt} |
| 1224 |
|
\label{eq:non-boussinesq} |
| 1225 |
\end{eqnarray} |
\end{eqnarray} |
| 1226 |
These equations permit acoustics modes, inertia-gravity waves, |
These equations permit acoustics modes, inertia-gravity waves, |
| 1227 |
non-hydrostatic motions, a geostrophic (Rossby) mode and a thermo-haline |
non-hydrostatic motions, a geostrophic (Rossby) mode and a thermohaline |
| 1228 |
mode. As written, they cannot be integrated forward consistently - if we |
mode. As written, they cannot be integrated forward consistently - if we |
| 1229 |
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 |
| 1230 |
consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref |
consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref |
| 1240 |
\end{equation} |
\end{equation} |
| 1241 |
|
|
| 1242 |
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 |
| 1243 |
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: |
|
| 1244 |
\begin{equation} |
\begin{equation} |
| 1245 |
\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{ |
| 1246 |
v}}+\partial _{z}w\approx 0 \label{eq-zns-pressure} |
v}}+\partial _{z}w\approx 0 \label{eq-zns-pressure} |
| 1430 |
and vertical direction respectively, are given by (see Fig.2) : |
and vertical direction respectively, are given by (see Fig.2) : |
| 1431 |
|
|
| 1432 |
\begin{equation*} |
\begin{equation*} |
| 1433 |
u=r\cos \phi \frac{D\lambda }{Dt} |
u=r\cos \varphi \frac{D\lambda }{Dt} |
| 1434 |
\end{equation*} |
\end{equation*} |
| 1435 |
|
|
| 1436 |
\begin{equation*} |
\begin{equation*} |
| 1437 |
v=r\frac{D\phi }{Dt}\qquad |
v=r\frac{D\varphi }{Dt}\qquad |
| 1438 |
\end{equation*} |
\end{equation*} |
| 1439 |
$\qquad \qquad \qquad \qquad $ |
$\qquad \qquad \qquad \qquad $ |
| 1440 |
|
|
| 1442 |
\dot{r}=\frac{Dr}{Dt} |
\dot{r}=\frac{Dr}{Dt} |
| 1443 |
\end{equation*} |
\end{equation*} |
| 1444 |
|
|
| 1445 |
Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial |
Here $\varphi $ is the latitude, $\lambda $ the longitude, $r$ the radial |
| 1446 |
distance of the particle from the center of the earth, $\Omega $ is the |
distance of the particle from the center of the earth, $\Omega $ is the |
| 1447 |
angular speed of rotation of the Earth and $D/Dt$ is the total derivative. |
angular speed of rotation of the Earth and $D/Dt$ is the total derivative. |
| 1448 |
|
|
| 1450 |
spherical coordinates: |
spherical coordinates: |
| 1451 |
|
|
| 1452 |
\begin{equation*} |
\begin{equation*} |
| 1453 |
\nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda } |
\nabla \equiv \left( \frac{1}{r\cos \varphi }\frac{\partial }{\partial \lambda } |
| 1454 |
,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r} |
,\frac{1}{r}\frac{\partial }{\partial \varphi },\frac{\partial }{\partial r} |
| 1455 |
\right) |
\right) |
| 1456 |
\end{equation*} |
\end{equation*} |
| 1457 |
|
|
| 1458 |
\begin{equation*} |
\begin{equation*} |
| 1459 |
\nabla .v\equiv \frac{1}{r\cos \phi }\left\{ \frac{\partial u}{\partial |
\nabla .v\equiv \frac{1}{r\cos \varphi }\left\{ \frac{\partial u}{\partial |
| 1460 |
\lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\} |
\lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\} |
| 1461 |
+\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} |
| 1462 |
\end{equation*} |
\end{equation*} |
| 1463 |
|
|