| 32 |
%tci%\tableofcontents |
%tci%\tableofcontents |
| 33 |
|
|
| 34 |
|
|
|
\part{MIT GCM basics} |
|
|
|
|
| 35 |
% Section: Overview |
% Section: Overview |
| 36 |
|
|
| 37 |
% $Header$ |
This document provides the reader with the information necessary to |
|
% $Name$ |
|
|
|
|
|
\section{Introduction} |
|
|
|
|
|
This documentation provides the reader with the information necessary to |
|
| 38 |
carry out numerical experiments using MITgcm. It gives a comprehensive |
carry out numerical experiments using MITgcm. It gives a comprehensive |
| 39 |
description of the continuous equations on which the model is based, the |
description of the continuous equations on which the model is based, the |
| 40 |
numerical algorithms the model employs and a description of the associated |
numerical algorithms the model employs and a description of the associated |
| 44 |
both process and general circulation studies of the atmosphere and ocean are |
both process and general circulation studies of the atmosphere and ocean are |
| 45 |
also presented. |
also presented. |
| 46 |
|
|
| 47 |
|
\section{Introduction} |
| 48 |
|
\begin{rawhtml} |
| 49 |
|
<!-- CMIREDIR:innovations: --> |
| 50 |
|
\end{rawhtml} |
| 51 |
|
|
| 52 |
|
|
| 53 |
MITgcm has a number of novel aspects: |
MITgcm has a number of novel aspects: |
| 54 |
|
|
| 55 |
\begin{itemize} |
\begin{itemize} |
| 56 |
\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 |
| 57 |
hydrodynamical kernel is used to drive forward both atmospheric and oceanic |
hydrodynamical kernel is used to drive forward both atmospheric and oceanic |
| 58 |
models - see fig |
models - see fig \ref{fig:onemodel} |
|
\marginpar{ |
|
|
Fig.1 One model}\ref{fig:onemodel} |
|
| 59 |
|
|
| 60 |
%% CNHbegin |
%% CNHbegin |
| 61 |
\input{part1/one_model_figure} |
\input{s_overview/text/one_model_figure} |
| 62 |
%% CNHend |
%% CNHend |
| 63 |
|
|
| 64 |
\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 |
| 65 |
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} |
|
| 66 |
|
|
| 67 |
%% CNHbegin |
%% CNHbegin |
| 68 |
\input{part1/all_scales_figure} |
\input{s_overview/text/all_scales_figure} |
| 69 |
%% CNHend |
%% CNHend |
| 70 |
|
|
| 71 |
\item finite volume techniques are employed yielding an intuitive |
\item finite volume techniques are employed yielding an intuitive |
| 72 |
discretization and support for the treatment of irregular geometries using |
discretization and support for the treatment of irregular geometries using |
| 73 |
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} |
|
| 74 |
|
|
| 75 |
%% CNHbegin |
%% CNHbegin |
| 76 |
\input{part1/fvol_figure} |
\input{s_overview/text/fvol_figure} |
| 77 |
%% CNHend |
%% CNHend |
| 78 |
|
|
| 79 |
\item tangent linear and adjoint counterparts are automatically maintained |
\item tangent linear and adjoint counterparts are automatically maintained |
| 84 |
computational platforms. |
computational platforms. |
| 85 |
\end{itemize} |
\end{itemize} |
| 86 |
|
|
| 87 |
|
|
| 88 |
Key publications reporting on and charting the development of the model are |
Key publications reporting on and charting the development of the model are |
| 89 |
listed in an Appendix. |
\cite{hill:95,marshall:97a,marshall:97b,adcroft:97,mars-eta:98,adcroft:99,hill:99,maro-eta:99,adcroft:04a,adcroft:04b,marshall:04} |
| 90 |
|
(an overview on the model formulation can also be found in \cite{adcroft:04c}): |
| 91 |
|
|
| 92 |
|
\begin{verbatim} |
| 93 |
|
Hill, C. and J. Marshall, (1995) |
| 94 |
|
Application of a Parallel Navier-Stokes Model to Ocean Circulation in |
| 95 |
|
Parallel Computational Fluid Dynamics |
| 96 |
|
In Proceedings of Parallel Computational Fluid Dynamics: Implementations |
| 97 |
|
and Results Using Parallel Computers, 545-552. |
| 98 |
|
Elsevier Science B.V.: New York |
| 99 |
|
|
| 100 |
|
Marshall, J., C. Hill, L. Perelman, and A. Adcroft, (1997) |
| 101 |
|
Hydrostatic, quasi-hydrostatic, and nonhydrostatic ocean modeling |
| 102 |
|
J. Geophysical Res., 102(C3), 5733-5752. |
| 103 |
|
|
| 104 |
|
Marshall, J., A. Adcroft, C. Hill, L. Perelman, and C. Heisey, (1997) |
| 105 |
|
A finite-volume, incompressible Navier Stokes model for studies of the ocean |
| 106 |
|
on parallel computers, |
| 107 |
|
J. Geophysical Res., 102(C3), 5753-5766. |
| 108 |
|
|
| 109 |
|
Adcroft, A.J., Hill, C.N. and J. Marshall, (1997) |
| 110 |
|
Representation of topography by shaved cells in a height coordinate ocean |
| 111 |
|
model |
| 112 |
|
Mon Wea Rev, vol 125, 2293-2315 |
| 113 |
|
|
| 114 |
|
Marshall, J., Jones, H. and C. Hill, (1998) |
| 115 |
|
Efficient ocean modeling using non-hydrostatic algorithms |
| 116 |
|
Journal of Marine Systems, 18, 115-134 |
| 117 |
|
|
| 118 |
|
Adcroft, A., Hill C. and J. Marshall: (1999) |
| 119 |
|
A new treatment of the Coriolis terms in C-grid models at both high and low |
| 120 |
|
resolutions, |
| 121 |
|
Mon. Wea. Rev. Vol 127, pages 1928-1936 |
| 122 |
|
|
| 123 |
|
Hill, C, Adcroft,A., Jamous,D., and J. Marshall, (1999) |
| 124 |
|
A Strategy for Terascale Climate Modeling. |
| 125 |
|
In Proceedings of the Eighth ECMWF Workshop on the Use of Parallel Processors |
| 126 |
|
in Meteorology, pages 406-425 |
| 127 |
|
World Scientific Publishing Co: UK |
| 128 |
|
|
| 129 |
|
Marotzke, J, Giering,R., Zhang, K.Q., Stammer,D., Hill,C., and T.Lee, (1999) |
| 130 |
|
Construction of the adjoint MIT ocean general circulation model and |
| 131 |
|
application to Atlantic heat transport variability |
| 132 |
|
J. Geophysical Res., 104(C12), 29,529-29,547. |
| 133 |
|
|
| 134 |
|
\end{verbatim} |
| 135 |
|
|
| 136 |
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 |
| 137 |
give a feel for the wide range of problems that can be addressed using it. |
give a feel for the wide range of problems that can be addressed using it. |
|
\pagebreak |
|
|
|
|
|
% $Header$ |
|
|
% $Name$ |
|
| 138 |
|
|
| 139 |
\section{Illustrations of the model in action} |
\section{Illustrations of the model in action} |
| 140 |
|
|
| 141 |
The MITgcm has been designed and used to model a wide range of phenomena, |
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 |
|
\begin{rawhtml} |
| 154 |
|
<!-- CMIREDIR:atmospheric_example: --> |
| 155 |
|
\end{rawhtml} |
| 156 |
|
|
|
A novel feature of MITgcm is its ability to simulate 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$mb$ |
|
| 159 |
|
A novel feature of MITgcm is its ability to simulate, using one basic algorithm, |
| 160 |
|
both atmospheric and oceanographic flows at both small and large scales. |
| 161 |
|
|
| 162 |
|
Figure \ref{fig:eddy_cs} shows an instantaneous plot of the 500$mb$ |
| 163 |
temperature field obtained using the atmospheric isomorph of MITgcm run at |
temperature field obtained using the atmospheric isomorph of MITgcm run at |
| 164 |
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 |
| 165 |
(blue) and warm air along an equatorial band (red). Fully developed |
(blue) and warm air along an equatorial band (red). Fully developed |
| 166 |
baroclinic eddies spawned in the northern hemisphere storm track are |
baroclinic eddies spawned in the northern hemisphere storm track are |
| 167 |
evident. There are no mountains or land-sea contrast in this calculation, |
evident. There are no mountains or land-sea contrast in this calculation, |
| 171 |
there are no mountains or land-sea contrast. |
there are no mountains or land-sea contrast. |
| 172 |
|
|
| 173 |
%% CNHbegin |
%% CNHbegin |
| 174 |
\input{part1/cubic_eddies_figure} |
\input{s_overview/text/cubic_eddies_figure} |
| 175 |
%% CNHend |
%% CNHend |
| 176 |
|
|
| 177 |
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 |
| 178 |
globe permitting a uniform gridding and obviated the need to fourier filter. |
globe permitting a uniform griding and obviated the need to Fourier filter. |
| 179 |
The `vector-invariant' form of MITgcm supports any orthogonal curvilinear |
The `vector-invariant' form of MITgcm supports any orthogonal curvilinear |
| 180 |
grid, of which the cubed sphere is just one of many choices. |
grid, of which the cubed sphere is just one of many choices. |
| 181 |
|
|
| 182 |
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 |
| 183 |
wind and meridional overturning streamfunction from a 20-level version of |
wind from a 20-level configuration of |
| 184 |
the model. It compares favorable with more conventional spatial |
the model. It compares favorable with more conventional spatial |
| 185 |
discretization approaches. |
discretization approaches. The two plots show the field calculated using the |
| 186 |
|
cube-sphere grid and the flow calculated using a regular, spherical polar |
| 187 |
A regular spherical lat-lon grid can also be used. |
latitude-longitude grid. Both grids are supported within the model. |
| 188 |
|
|
| 189 |
%% CNHbegin |
%% CNHbegin |
| 190 |
\input{part1/hs_zave_u_figure} |
\input{s_overview/text/hs_zave_u_figure} |
| 191 |
%% CNHend |
%% CNHend |
| 192 |
|
|
| 193 |
\subsection{Ocean gyres} |
\subsection{Ocean gyres} |
| 194 |
|
\begin{rawhtml} |
| 195 |
|
<!-- CMIREDIR:oceanic_example: --> |
| 196 |
|
\end{rawhtml} |
| 197 |
|
\begin{rawhtml} |
| 198 |
|
<!-- CMIREDIR:ocean_gyres: --> |
| 199 |
|
\end{rawhtml} |
| 200 |
|
|
| 201 |
Baroclinic instability is a ubiquitous process in the ocean, as well as the |
Baroclinic instability is a ubiquitous process in the ocean, as well as the |
| 202 |
atmosphere. Ocean eddies play an important role in modifying the |
atmosphere. Ocean eddies play an important role in modifying the |
| 206 |
increased until the baroclinic instability process is resolved, numerical |
increased until the baroclinic instability process is resolved, numerical |
| 207 |
solutions of a different and much more realistic kind, can be obtained. |
solutions of a different and much more realistic kind, can be obtained. |
| 208 |
|
|
| 209 |
Fig. ?.? shows the surface temperature and velocity field obtained from |
Figure \ref{fig:ocean-gyres} shows the surface temperature and |
| 210 |
MITgcm run at $\frac{1}{6}^{\circ }$ horizontal resolution on a $lat-lon$ |
velocity field obtained from MITgcm run at $\frac{1}{6}^{\circ }$ |
| 211 |
grid in which the pole has been rotated by 90$^{\circ }$ on to the equator |
horizontal resolution on a \textit{lat-lon} grid in which the pole has |
| 212 |
(to avoid the converging of meridian in northern latitudes). 21 vertical |
been rotated by $90^{\circ }$ on to the equator (to avoid the |
| 213 |
levels are used in the vertical with a `lopped cell' representation of |
converging of meridian in northern latitudes). 21 vertical levels are |
| 214 |
topography. The development and propagation of anomalously warm and cold |
used in the vertical with a `lopped cell' representation of |
| 215 |
eddies can be clearly been seen in the Gulf Stream region. The transport of |
topography. The development and propagation of anomalously warm and |
| 216 |
warm water northward by the mean flow of the Gulf Stream is also clearly |
cold eddies can be clearly seen in the Gulf Stream region. The |
| 217 |
visible. |
transport of warm water northward by the mean flow of the Gulf Stream |
| 218 |
|
is also clearly visible. |
| 219 |
|
|
| 220 |
%% CNHbegin |
%% CNHbegin |
| 221 |
\input{part1/ocean_gyres_figure} |
\input{s_overview/text/atl6_figure} |
| 222 |
%% CNHend |
%% CNHend |
| 223 |
|
|
| 224 |
|
|
| 225 |
\subsection{Global ocean circulation} |
\subsection{Global ocean circulation} |
| 226 |
|
\begin{rawhtml} |
| 227 |
|
<!-- CMIREDIR:global_ocean_circulation: --> |
| 228 |
|
\end{rawhtml} |
| 229 |
|
|
| 230 |
|
Figure \ref{fig:large-scale-circ} (top) shows the pattern of ocean |
| 231 |
|
currents at the surface of a $4^{\circ }$ global ocean model run with |
| 232 |
|
15 vertical levels. Lopped cells are used to represent topography on a |
| 233 |
|
regular \textit{lat-lon} grid extending from $70^{\circ }N$ to |
| 234 |
|
$70^{\circ }S$. The model is driven using monthly-mean winds with |
| 235 |
|
mixed boundary conditions on temperature and salinity at the surface. |
| 236 |
|
The transfer properties of ocean eddies, convection and mixing is |
| 237 |
|
parameterized in this model. |
| 238 |
|
|
| 239 |
Fig.E2a shows the pattern of ocean currents at the surface of a 4$^{\circ }$ |
Figure \ref{fig:large-scale-circ} (bottom) shows the meridional overturning |
| 240 |
global ocean model run with 15 vertical levels. Lopped cells are used to |
circulation of the global ocean in Sverdrups. |
|
represent topography on a regular $lat-lon$ grid extending from 70$^{\circ |
|
|
}N $ to 70$^{\circ }S$. The model is driven using monthly-mean winds with |
|
|
mixed boundary conditions on temperature and salinity at the surface. The |
|
|
transfer properties of ocean eddies, convection and mixing is parameterized |
|
|
in this model. |
|
|
|
|
|
Fig.E2b shows the meridional overturning circulation of the global ocean in |
|
|
Sverdrups. |
|
| 241 |
|
|
| 242 |
%%CNHbegin |
%%CNHbegin |
| 243 |
\input{part1/global_circ_figure} |
\input{s_overview/text/global_circ_figure} |
| 244 |
%%CNHend |
%%CNHend |
| 245 |
|
|
| 246 |
\subsection{Convection and mixing over topography} |
\subsection{Convection and mixing over topography} |
| 247 |
|
\begin{rawhtml} |
| 248 |
|
<!-- CMIREDIR:mixing_over_topography: --> |
| 249 |
|
\end{rawhtml} |
| 250 |
|
|
| 251 |
|
|
| 252 |
Dense plumes generated by localized cooling on the continental shelf of the |
Dense plumes generated by localized cooling on the continental shelf of the |
| 253 |
ocean may be influenced by rotation when the deformation radius is smaller |
ocean may be influenced by rotation when the deformation radius is smaller |
| 254 |
than the width of the cooling region. Rather than gravity plumes, the |
than the width of the cooling region. Rather than gravity plumes, the |
| 255 |
mechanism for moving dense fluid down the shelf is then through geostrophic |
mechanism for moving dense fluid down the shelf is then through geostrophic |
| 256 |
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} |
| 257 |
|
(blue is cold dense fluid, red is |
| 258 |
warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to |
warmer, lighter fluid) employs the non-hydrostatic capability of MITgcm to |
| 259 |
trigger convection by surface cooling. The cold, dense water falls down the |
trigger convection by surface cooling. The cold, dense water falls down the |
| 260 |
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 |
| 263 |
instability of the along-slope current. |
instability of the along-slope current. |
| 264 |
|
|
| 265 |
%%CNHbegin |
%%CNHbegin |
| 266 |
\input{part1/convect_and_topo} |
\input{s_overview/text/convect_and_topo} |
| 267 |
%%CNHend |
%%CNHend |
| 268 |
|
|
| 269 |
\subsection{Boundary forced internal waves} |
\subsection{Boundary forced internal waves} |
| 270 |
|
\begin{rawhtml} |
| 271 |
|
<!-- CMIREDIR:boundary_forced_internal_waves: --> |
| 272 |
|
\end{rawhtml} |
| 273 |
|
|
| 274 |
The unique ability of MITgcm to treat non-hydrostatic dynamics in the |
The unique ability of MITgcm to treat non-hydrostatic dynamics in the |
| 275 |
presence of complex geometry makes it an ideal tool to study internal wave |
presence of complex geometry makes it an ideal tool to study internal wave |
| 276 |
dynamics and mixing in oceanic canyons and ridges driven by large amplitude |
dynamics and mixing in oceanic canyons and ridges driven by large amplitude |
| 277 |
barotropic tidal currents imposed through open boundary conditions. |
barotropic tidal currents imposed through open boundary conditions. |
| 278 |
|
|
| 279 |
Fig. ?.? shows the influence of cross-slope topographic variations on |
Fig. \ref{fig:boundary-forced-wave} shows the influence of cross-slope |
| 280 |
|
topographic variations on |
| 281 |
internal wave breaking - the cross-slope velocity is in color, the density |
internal wave breaking - the cross-slope velocity is in color, the density |
| 282 |
contoured. The internal waves are excited by application of open boundary |
contoured. The internal waves are excited by application of open boundary |
| 283 |
conditions on the left.\ They propagate to the sloping boundary (represented |
conditions on the left. They propagate to the sloping boundary (represented |
| 284 |
using MITgcm's finite volume spatial discretization) where they break under |
using MITgcm's finite volume spatial discretization) where they break under |
| 285 |
nonhydrostatic dynamics. |
nonhydrostatic dynamics. |
| 286 |
|
|
| 287 |
%%CNHbegin |
%%CNHbegin |
| 288 |
\input{part1/boundary_forced_waves} |
\input{s_overview/text/boundary_forced_waves} |
| 289 |
%%CNHend |
%%CNHend |
| 290 |
|
|
| 291 |
\subsection{Parameter sensitivity using the adjoint of MITgcm} |
\subsection{Parameter sensitivity using the adjoint of MITgcm} |
| 292 |
|
\begin{rawhtml} |
| 293 |
|
<!-- CMIREDIR:parameter_sensitivity: --> |
| 294 |
|
\end{rawhtml} |
| 295 |
|
|
| 296 |
Forward and tangent linear counterparts of MITgcm are supported using an |
Forward and tangent linear counterparts of MITgcm are supported using an |
| 297 |
`automatic adjoint compiler'. These can be used in parameter sensitivity and |
`automatic adjoint compiler'. These can be used in parameter sensitivity and |
| 298 |
data assimilation studies. |
data assimilation studies. |
| 299 |
|
|
| 300 |
As one example of application of the MITgcm adjoint, Fig.E4 maps the |
As one example of application of the MITgcm adjoint, Figure |
| 301 |
gradient $\frac{\partial J}{\partial \mathcal{H}}$where $J$ is the magnitude |
\ref{fig:hf-sensitivity} maps the gradient $\frac{\partial J}{\partial |
| 302 |
of the overturning streamfunction shown in fig?.? at 40$^{\circ }$N and $ |
\mathcal{H}}$where $J$ is the magnitude of the overturning |
| 303 |
\mathcal{H}$ is the air-sea heat flux 100 years before. We see that $J$ is |
stream-function shown in figure \ref{fig:large-scale-circ} at |
| 304 |
sensitive to heat fluxes over the Labrador Sea, one of the important sources |
$60^{\circ }N$ and $ \mathcal{H}(\lambda,\varphi)$ is the mean, local |
| 305 |
of deep water for the thermohaline circulations. This calculation also |
air-sea heat flux over a 100 year period. We see that $J$ is sensitive |
| 306 |
|
to heat fluxes over the Labrador Sea, one of the important sources of |
| 307 |
|
deep water for the thermohaline circulations. This calculation also |
| 308 |
yields sensitivities to all other model parameters. |
yields sensitivities to all other model parameters. |
| 309 |
|
|
| 310 |
%%CNHbegin |
%%CNHbegin |
| 311 |
\input{part1/adj_hf_ocean_figure} |
\input{s_overview/text/adj_hf_ocean_figure} |
| 312 |
%%CNHend |
%%CNHend |
| 313 |
|
|
| 314 |
\subsection{Global state estimation of the ocean} |
\subsection{Global state estimation of the ocean} |
| 315 |
|
\begin{rawhtml} |
| 316 |
|
<!-- CMIREDIR:global_state_estimation: --> |
| 317 |
|
\end{rawhtml} |
| 318 |
|
|
| 319 |
|
|
| 320 |
An important application of MITgcm is in state estimation of the global |
An important application of MITgcm is in state estimation of the global |
| 321 |
ocean circulation. An appropriately defined `cost function', which measures |
ocean circulation. An appropriately defined `cost function', which measures |
| 322 |
the departure of the model from observations (both remotely sensed and |
the departure of the model from observations (both remotely sensed and |
| 323 |
insitu) over an interval of time, is minimized by adjusting `control |
in-situ) over an interval of time, is minimized by adjusting `control |
| 324 |
parameters' such as air-sea fluxes, the wind field, the initial conditions |
parameters' such as air-sea fluxes, the wind field, the initial conditions |
| 325 |
etc. Figure ?.? shows an estimate of the time-mean surface elevation of the |
etc. Figure \ref{fig:assimilated-globes} shows the large scale planetary |
| 326 |
ocean obtained by bringing the model in to consistency with altimetric and |
circulation and a Hopf-Muller plot of Equatorial sea-surface height. |
| 327 |
in-situ observations over the period 1992-1997. |
Both are obtained from assimilation bringing the model in to |
| 328 |
|
consistency with altimetric and in-situ observations over the period |
| 329 |
|
1992-1997. |
| 330 |
|
|
| 331 |
%% CNHbegin |
%% CNHbegin |
| 332 |
\input{part1/globes_figure} |
\input{s_overview/text/assim_figure} |
| 333 |
%% CNHend |
%% CNHend |
| 334 |
|
|
| 335 |
\subsection{Ocean biogeochemical cycles} |
\subsection{Ocean biogeochemical cycles} |
| 336 |
|
\begin{rawhtml} |
| 337 |
MITgcm is being used to study global biogeochemical cycles in the ocean. For |
<!-- CMIREDIR:ocean_biogeo_cycles: --> |
| 338 |
example one can study the effects of interannual changes in meteorological |
\end{rawhtml} |
| 339 |
forcing and upper ocean circulation on the fluxes of carbon dioxide and |
|
| 340 |
oxygen between the ocean and atmosphere. The figure shows the annual air-sea |
MITgcm is being used to study global biogeochemical cycles in the |
| 341 |
flux of oxygen and its relation to density outcrops in the southern oceans |
ocean. For example one can study the effects of interannual changes in |
| 342 |
from a single year of a global, interannually varying simulation. |
meteorological forcing and upper ocean circulation on the fluxes of |
| 343 |
|
carbon dioxide and oxygen between the ocean and atmosphere. Figure |
| 344 |
|
\ref{fig:biogeo} shows the annual air-sea flux of oxygen and its |
| 345 |
|
relation to density outcrops in the southern oceans from a single year |
| 346 |
|
of a global, interannually varying simulation. The simulation is run |
| 347 |
|
at $1^{\circ}\times1^{\circ}$ resolution telescoping to |
| 348 |
|
$\frac{1}{3}^{\circ}\times\frac{1}{3}^{\circ}$ in the tropics (not |
| 349 |
|
shown). |
| 350 |
|
|
| 351 |
%%CNHbegin |
%%CNHbegin |
| 352 |
\input{part1/biogeo_figure} |
\input{s_overview/text/biogeo_figure} |
| 353 |
%%CNHend |
%%CNHend |
| 354 |
|
|
| 355 |
\subsection{Simulations of laboratory experiments} |
\subsection{Simulations of laboratory experiments} |
| 356 |
|
\begin{rawhtml} |
| 357 |
|
<!-- CMIREDIR:classroom_exp: --> |
| 358 |
|
\end{rawhtml} |
| 359 |
|
|
| 360 |
Figure ?.? shows MITgcm being used to simulate a laboratory experiment |
Figure \ref{fig:lab-simulation} shows MITgcm being used to simulate a |
| 361 |
enquiring in to the dynamics of the Antarctic Circumpolar Current (ACC). An |
laboratory experiment inquiring into the dynamics of the Antarctic Circumpolar Current (ACC). An |
| 362 |
initially homogeneous tank of water ($1m$ in diameter) is driven from its |
initially homogeneous tank of water ($1m$ in diameter) is driven from its |
| 363 |
free surface by a rotating heated disk. The combined action of mechanical |
free surface by a rotating heated disk. The combined action of mechanical |
| 364 |
and thermal forcing creates a lens of fluid which becomes baroclinically |
and thermal forcing creates a lens of fluid which becomes baroclinically |
| 365 |
unstable. The stratification and depth of penetration of the lens is |
unstable. The stratification and depth of penetration of the lens is |
| 366 |
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 |
| 367 |
stratification of the ACC. |
stratification of the ACC. |
| 368 |
|
|
| 369 |
%%CNHbegin |
%%CNHbegin |
| 370 |
\input{part1/lab_figure} |
\input{s_overview/text/lab_figure} |
| 371 |
%%CNHend |
%%CNHend |
| 372 |
|
|
|
% $Header$ |
|
|
% $Name$ |
|
|
|
|
| 373 |
\section{Continuous equations in `r' coordinates} |
\section{Continuous equations in `r' coordinates} |
| 374 |
|
\begin{rawhtml} |
| 375 |
|
<!-- CMIREDIR:z-p_isomorphism: --> |
| 376 |
|
\end{rawhtml} |
| 377 |
|
|
| 378 |
To render atmosphere and ocean models from one dynamical core we exploit |
To render atmosphere and ocean models from one dynamical core we exploit |
| 379 |
`isomorphisms' between equation sets that govern the evolution of the |
`isomorphisms' between equation sets that govern the evolution of the |
| 380 |
respective fluids - see fig.4 |
respective fluids - see figure \ref{fig:isomorphic-equations}. |
| 381 |
\marginpar{ |
One system of hydrodynamical equations is written down |
|
Fig.4. Isomorphisms}. One system of hydrodynamical equations is written down |
|
| 382 |
and encoded. The model variables have different interpretations depending on |
and encoded. The model variables have different interpretations depending on |
| 383 |
whether the atmosphere or ocean is being studied. Thus, for example, the |
whether the atmosphere or ocean is being studied. Thus, for example, the |
| 384 |
vertical coordinate `$r$' is interpreted as pressure, $p$, if we are |
vertical coordinate `$r$' is interpreted as pressure, $p$, if we are |
| 385 |
modeling the atmosphere and height, $z$, if we are modeling the ocean. |
modeling the atmosphere (right hand side of figure \ref{fig:isomorphic-equations}) |
| 386 |
|
and height, $z$, if we are modeling the ocean (left hand side of figure |
| 387 |
|
\ref{fig:isomorphic-equations}). |
| 388 |
|
|
| 389 |
%%CNHbegin |
%%CNHbegin |
| 390 |
\input{part1/zandpcoord_figure.tex} |
\input{s_overview/text/zandpcoord_figure.tex} |
| 391 |
%%CNHend |
%%CNHend |
| 392 |
|
|
| 393 |
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 |
| 396 |
depend on $\theta $, $S$, and $p$. The equations that govern the evolution |
depend on $\theta $, $S$, and $p$. The equations that govern the evolution |
| 397 |
of these fields, obtained by applying the laws of classical mechanics and |
of these fields, obtained by applying the laws of classical mechanics and |
| 398 |
thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of |
thermodynamics to a Boussinesq, Navier-Stokes fluid are, written in terms of |
| 399 |
a generic vertical coordinate, $r$, see fig.5 |
a generic vertical coordinate, $r$, so that the appropriate |
| 400 |
\marginpar{ |
kinematic boundary conditions can be applied isomorphically |
| 401 |
Fig.5 The vertical coordinate of model}: |
see figure \ref{fig:zandp-vert-coord}. |
| 402 |
|
|
| 403 |
%%CNHbegin |
%%CNHbegin |
| 404 |
\input{part1/vertcoord_figure.tex} |
\input{s_overview/text/vertcoord_figure.tex} |
| 405 |
%%CNHend |
%%CNHend |
| 406 |
|
|
| 407 |
\begin{equation*} |
\begin{equation} |
| 408 |
\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}} |
| 409 |
\right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}} |
\right) _{h}+\mathbf{\nabla }_{h}\phi =\mathcal{F}_{\vec{\mathbf{v}_{h}}} |
| 410 |
\text{ horizontal mtm} |
\text{ horizontal mtm} \label{eq:horizontal_mtm} |
| 411 |
\end{equation*} |
\end{equation} |
| 412 |
|
|
| 413 |
\begin{equation*} |
\begin{equation} |
| 414 |
\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{ |
| 415 |
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{ |
| 416 |
vertical mtm} |
vertical mtm} \label{eq:vertical_mtm} |
| 417 |
\end{equation*} |
\end{equation} |
| 418 |
|
|
| 419 |
\begin{equation} |
\begin{equation} |
| 420 |
\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{ |
\mathbf{\nabla }_{h}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \dot{r}}{ |
| 421 |
\partial r}=0\text{ continuity} \label{eq:continuous} |
\partial r}=0\text{ continuity} \label{eq:continuity} |
| 422 |
\end{equation} |
\end{equation} |
| 423 |
|
|
| 424 |
\begin{equation*} |
\begin{equation} |
| 425 |
b=b(\theta ,S,r)\text{ equation of state} |
b=b(\theta ,S,r)\text{ equation of state} \label{eq:equation_of_state} |
| 426 |
\end{equation*} |
\end{equation} |
| 427 |
|
|
| 428 |
\begin{equation*} |
\begin{equation} |
| 429 |
\frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature} |
\frac{D\theta }{Dt}=\mathcal{Q}_{\theta }\text{ potential temperature} |
| 430 |
\end{equation*} |
\label{eq:potential_temperature} |
| 431 |
|
\end{equation} |
| 432 |
|
|
| 433 |
\begin{equation*} |
\begin{equation} |
| 434 |
\frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity} |
\frac{DS}{Dt}=\mathcal{Q}_{S}\text{ humidity/salinity} |
| 435 |
\end{equation*} |
\label{eq:humidity_salt} |
| 436 |
|
\end{equation} |
| 437 |
|
|
| 438 |
Here: |
Here: |
| 439 |
|
|
| 497 |
\end{equation*} |
\end{equation*} |
| 498 |
|
|
| 499 |
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 |
| 500 |
extensive `physics' packages for atmosphere and ocean described in Chapter 6. |
`physics' and forcing packages for atmosphere and ocean. These are described |
| 501 |
|
in later chapters. |
| 502 |
|
|
| 503 |
\subsection{Kinematic Boundary conditions} |
\subsection{Kinematic Boundary conditions} |
| 504 |
|
|
| 505 |
\subsubsection{vertical} |
\subsubsection{vertical} |
| 506 |
|
|
| 507 |
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}): |
| 508 |
|
|
| 509 |
\begin{equation} |
\begin{equation} |
| 510 |
\dot{r}=0atr=R_{fixed}(x,y)\text{ (ocean bottom, top of the atmosphere)} |
\dot{r}=0 \text{\ at\ } r=R_{fixed}(x,y)\text{ (ocean bottom, top of the atmosphere)} |
| 511 |
\label{eq:fixedbc} |
\label{eq:fixedbc} |
| 512 |
\end{equation} |
\end{equation} |
| 513 |
|
|
| 514 |
\begin{equation} |
\begin{equation} |
| 515 |
\dot{r}=\frac{Dr}{Dt}atr=R_{moving}\text{ \ |
\dot{r}=\frac{Dr}{Dt} \text{\ at\ } r=R_{moving}\text{ \ |
| 516 |
(oceansurface,bottomoftheatmosphere)} \label{eq:movingbc} |
(ocean surface,bottom of the atmosphere)} \label{eq:movingbc} |
| 517 |
\end{equation} |
\end{equation} |
| 518 |
|
|
| 519 |
Here |
Here |
| 535 |
|
|
| 536 |
\subsection{Atmosphere} |
\subsection{Atmosphere} |
| 537 |
|
|
| 538 |
In the atmosphere, see fig.5, we interpret: |
In the atmosphere, (see figure \ref{fig:zandp-vert-coord}), we interpret: |
| 539 |
|
|
| 540 |
\begin{equation} |
\begin{equation} |
| 541 |
r=p\text{ is the pressure} \label{eq:atmos-r} |
r=p\text{ is the pressure} \label{eq:atmos-r} |
| 606 |
atmosphere)} \label{eq:moving-bc-atmos} |
atmosphere)} \label{eq:moving-bc-atmos} |
| 607 |
\end{eqnarray} |
\end{eqnarray} |
| 608 |
|
|
| 609 |
Then the (hydrostatic form of) eq(\ref{eq:continuous}) yields a consistent |
Then the (hydrostatic form of) equations |
| 610 |
set of atmospheric equations which, for convenience, are written out in $p$ |
(\ref{eq:horizontal_mtm}-\ref{eq:humidity_salt}) yields a consistent |
| 611 |
coordinates in Appendix Atmosphere - see eqs(\ref{eq:atmos-prime}). |
set of atmospheric equations which, for convenience, are written out |
| 612 |
|
in $p$ coordinates in Appendix Atmosphere - see |
| 613 |
|
eqs(\ref{eq:atmos-prime}). |
| 614 |
|
|
| 615 |
\subsection{Ocean} |
\subsection{Ocean} |
| 616 |
|
|
| 645 |
\end{eqnarray} |
\end{eqnarray} |
| 646 |
where $\eta $ is the elevation of the free surface. |
where $\eta $ is the elevation of the free surface. |
| 647 |
|
|
| 648 |
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 |
| 649 |
|
of oceanic equations |
| 650 |
which, for convenience, are written out in $z$ coordinates in Appendix Ocean |
which, for convenience, are written out in $z$ coordinates in Appendix Ocean |
| 651 |
- see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}). |
- see eqs(\ref{eq:ocean-mom}) to (\ref{eq:ocean-salt}). |
| 652 |
|
|
| 653 |
\subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and |
\subsection{Hydrostatic, Quasi-hydrostatic, Quasi-nonhydrostatic and |
| 654 |
Non-hydrostatic forms} |
Non-hydrostatic forms} |
| 655 |
|
\label{sec:all_hydrostatic_forms} |
| 656 |
|
\begin{rawhtml} |
| 657 |
|
<!-- CMIREDIR:non_hydrostatic: --> |
| 658 |
|
\end{rawhtml} |
| 659 |
|
|
| 660 |
|
|
| 661 |
Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms: |
Let us separate $\phi $ in to surface, hydrostatic and non-hydrostatic terms: |
| 662 |
|
|
| 664 |
\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) |
| 665 |
\label{eq:phi-split} |
\label{eq:phi-split} |
| 666 |
\end{equation} |
\end{equation} |
| 667 |
and write eq(\ref{incompressible}a,b) in the form: |
%and write eq(\ref{eq:incompressible}) in the form: |
| 668 |
|
% ^- this eq is missing (jmc) ; replaced with: |
| 669 |
|
and write eq( \ref{eq:horizontal_mtm}) in the form: |
| 670 |
|
|
| 671 |
\begin{equation} |
\begin{equation} |
| 672 |
\frac{\partial \vec{\mathbf{v}_{h}}}{\partial t}+\mathbf{\nabla }_{h}\phi |
\frac{\partial \vec{\mathbf{v}_{h}}}{\partial t}+\mathbf{\nabla }_{h}\phi |
| 699 |
\left. |
\left. |
| 700 |
\begin{tabular}{l} |
\begin{tabular}{l} |
| 701 |
$G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\ |
$G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\ |
| 702 |
$-\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\} $ |
| 703 |
\\ |
\\ |
| 704 |
$-\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\} $ |
| 705 |
\\ |
\\ |
| 706 |
$+\mathcal{F}_{u}$ |
$+\mathcal{F}_{u}$ |
| 707 |
\end{tabular} |
\end{tabular} |
| 719 |
\left. |
\left. |
| 720 |
\begin{tabular}{l} |
\begin{tabular}{l} |
| 721 |
$G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\ |
$G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\ |
| 722 |
$-\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\} |
| 723 |
$ \\ |
$ \\ |
| 724 |
$-\left\{ -2\Omega u\sin lat\right\} $ \\ |
$-\left\{ -2\Omega u\sin \varphi \right\} $ \\ |
| 725 |
$+\mathcal{F}_{v}$ |
$+\mathcal{F}_{v}$ |
| 726 |
\end{tabular} |
\end{tabular} |
| 727 |
\ \right\} \left\{ |
\ \right\} \left\{ |
| 740 |
\begin{tabular}{l} |
\begin{tabular}{l} |
| 741 |
$G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\ |
$G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\ |
| 742 |
$+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\ |
$+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\ |
| 743 |
${+}\underline{{2\Omega u\cos lat}}$ \\ |
${+}\underline{{2\Omega u\cos \varphi}}$ \\ |
| 744 |
$\underline{\underline{\mathcal{F}_{\dot{r}}}}$ |
$\underline{\underline{\mathcal{F}_{\dot{r}}}}$ |
| 745 |
\end{tabular} |
\end{tabular} |
| 746 |
\ \right\} \left\{ |
\ \right\} \left\{ |
| 754 |
\end{equation} |
\end{equation} |
| 755 |
\qquad \qquad \qquad \qquad \qquad |
\qquad \qquad \qquad \qquad \qquad |
| 756 |
|
|
| 757 |
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 `$\varphi$ |
| 758 |
' is latitude. |
' is latitude. |
| 759 |
|
|
| 760 |
Grad and div operators in spherical coordinates are defined in appendix |
Grad and div operators in spherical coordinates are defined in appendix |
| 761 |
OPERATORS. |
OPERATORS. |
|
\marginpar{ |
|
|
Fig.6 Spherical polar coordinate system.} |
|
| 762 |
|
|
| 763 |
%%CNHbegin |
%%CNHbegin |
| 764 |
\input{part1/sphere_coord_figure.tex} |
\input{s_overview/text/sphere_coord_figure.tex} |
| 765 |
%%CNHend |
%%CNHend |
| 766 |
|
|
| 767 |
\subsubsection{Shallow atmosphere approximation} |
\subsubsection{Shallow atmosphere approximation} |
| 768 |
|
|
| 769 |
Most models are based on the `hydrostatic primitive equations' (HPE's) in |
Most models are based on the `hydrostatic primitive equations' (HPE's) |
| 770 |
which the vertical momentum equation is reduced to a statement of |
in which the vertical momentum equation is reduced to a statement of |
| 771 |
hydrostatic balance and the `traditional approximation' is made in which the |
hydrostatic balance and the `traditional approximation' is made in |
| 772 |
Coriolis force is treated approximately and the shallow atmosphere |
which the Coriolis force is treated approximately and the shallow |
| 773 |
approximation is made.\ The MITgcm need not make the `traditional |
atmosphere approximation is made. MITgcm need not make the |
| 774 |
approximation'. To be able to support consistent non-hydrostatic forms the |
`traditional approximation'. To be able to support consistent |
| 775 |
shallow atmosphere approximation can be relaxed - when dividing through by $ |
non-hydrostatic forms the shallow atmosphere approximation can be |
| 776 |
r $ in, for example, (\ref{eq:gu-speherical}), we do not replace $r$ by $a$, |
relaxed - when dividing through by $ r $ in, for example, |
| 777 |
the radius of the earth. |
(\ref{eq:gu-speherical}), we do not replace $r$ by $a$, the radius of |
| 778 |
|
the earth. |
| 779 |
|
|
| 780 |
\subsubsection{Hydrostatic and quasi-hydrostatic forms} |
\subsubsection{Hydrostatic and quasi-hydrostatic forms} |
| 781 |
|
\label{sec:hydrostatic_and_quasi-hydrostatic_forms} |
| 782 |
|
|
| 783 |
These are discussed at length in Marshall et al (1997a). |
These are discussed at length in Marshall et al (1997a). |
| 784 |
|
|
| 792 |
|
|
| 793 |
In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between |
In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between |
| 794 |
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 |
| 795 |
\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 |
| 796 |
contribution to the pressure field: only the terms underlined twice in Eqs. ( |
contribution to the pressure field: only the terms underlined twice in Eqs. ( |
| 797 |
\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 |
| 798 |
and, simultaneously, the shallow atmosphere approximation is relaxed. In |
and, simultaneously, the shallow atmosphere approximation is relaxed. In |
| 801 |
vertical momentum equation (\ref{eq:mom-w}) becomes: |
vertical momentum equation (\ref{eq:mom-w}) becomes: |
| 802 |
|
|
| 803 |
\begin{equation*} |
\begin{equation*} |
| 804 |
\frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat |
\frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos \varphi |
| 805 |
\end{equation*} |
\end{equation*} |
| 806 |
making a small correction to the hydrostatic pressure. |
making a small correction to the hydrostatic pressure. |
| 807 |
|
|
| 812 |
|
|
| 813 |
\subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms} |
\subsubsection{Non-hydrostatic and quasi-nonhydrostatic forms} |
| 814 |
|
|
| 815 |
The MIT model presently supports a full non-hydrostatic ocean isomorph, but |
MITgcm presently supports a full non-hydrostatic ocean isomorph, but |
| 816 |
only a quasi-non-hydrostatic atmospheric isomorph. |
only a quasi-non-hydrostatic atmospheric isomorph. |
| 817 |
|
|
| 818 |
\paragraph{Non-hydrostatic Ocean} |
\paragraph{Non-hydrostatic Ocean} |
| 822 |
three dimensional elliptic equation must be solved subject to Neumann |
three dimensional elliptic equation must be solved subject to Neumann |
| 823 |
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 |
| 824 |
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 |
| 825 |
incompressible condition eq(\ref{eq:continuous})c has already filtered out |
incompressible condition eq(\ref{eq:continuity}) has already filtered out |
| 826 |
acoustic modes. It does, however, ensure that the gravity waves are treated |
acoustic modes. It does, however, ensure that the gravity waves are treated |
| 827 |
accurately with an exact dispersion relation. The \textbf{NH} set has a |
accurately with an exact dispersion relation. The \textbf{NH} set has a |
| 828 |
complete angular momentum principle and consistent energetics - see White |
complete angular momentum principle and consistent energetics - see White |
| 871 |
\subsection{Solution strategy} |
\subsection{Solution strategy} |
| 872 |
|
|
| 873 |
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{ |
| 874 |
NH} models is summarized in Fig.7. |
NH} models is summarized in Figure \ref{fig:solution-strategy}. |
| 875 |
\marginpar{ |
Under all dynamics, a 2-d elliptic equation is |
|
Fig.7 Solution strategy} Under all dynamics, a 2-d elliptic equation is |
|
| 876 |
first solved to find the surface pressure and the hydrostatic pressure at |
first solved to find the surface pressure and the hydrostatic pressure at |
| 877 |
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 |
| 878 |
\textbf{QH} dynamics, the horizontal momentum equations are then stepped |
\textbf{QH} dynamics, the horizontal momentum equations are then stepped |
| 882 |
stepping forward the vertical momentum equation. |
stepping forward the vertical momentum equation. |
| 883 |
|
|
| 884 |
%%CNHbegin |
%%CNHbegin |
| 885 |
\input{part1/solution_strategy_figure.tex} |
\input{s_overview/text/solution_strategy_figure.tex} |
| 886 |
%%CNHend |
%%CNHend |
| 887 |
|
|
| 888 |
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 |
| 889 |
course, some complication that goes with the inclusion of $\cos \phi \ $ |
course, some complication that goes with the inclusion of $\cos \varphi \ $ |
| 890 |
Coriolis terms and the relaxation of the shallow atmosphere approximation. |
Coriolis terms and the relaxation of the shallow atmosphere approximation. |
| 891 |
But this leads to negligible increase in computation. In \textbf{NH}, in |
But this leads to negligible increase in computation. In \textbf{NH}, in |
| 892 |
contrast, one additional elliptic equation - a three-dimensional one - must |
contrast, one additional elliptic equation - a three-dimensional one - must |
| 896 |
hydrostatic limit, is as computationally economic as the \textbf{HPEs}. |
hydrostatic limit, is as computationally economic as the \textbf{HPEs}. |
| 897 |
|
|
| 898 |
\subsection{Finding the pressure field} |
\subsection{Finding the pressure field} |
| 899 |
|
\label{sec:finding_the_pressure_field} |
| 900 |
|
|
| 901 |
Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the |
Unlike the prognostic variables $u$, $v$, $w$, $\theta $ and $S$, the |
| 902 |
pressure field must be obtained diagnostically. We proceed, as before, by |
pressure field must be obtained diagnostically. We proceed, as before, by |
| 929 |
|
|
| 930 |
\subsubsection{Surface pressure} |
\subsubsection{Surface pressure} |
| 931 |
|
|
| 932 |
The surface pressure equation can be obtained by integrating continuity, ( |
The surface pressure equation can be obtained by integrating continuity, |
| 933 |
\ref{eq:continuous})c, vertically from $r=R_{fixed}$ to $r=R_{moving}$ |
(\ref{eq:continuity}), vertically from $r=R_{fixed}$ to $r=R_{moving}$ |
| 934 |
|
|
| 935 |
\begin{equation*} |
\begin{equation*} |
| 936 |
\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} |
| 955 |
where we have incorporated a source term. |
where we have incorporated a source term. |
| 956 |
|
|
| 957 |
Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential |
Whether $\phi $ is pressure (ocean model, $p/\rho _{c}$) or geopotential |
| 958 |
(atmospheric model), in (\ref{mtm-split}), the horizontal gradient term can |
(atmospheric model), in (\ref{eq:mom-h}), the horizontal gradient term can |
| 959 |
be written |
be written |
| 960 |
\begin{equation} |
\begin{equation} |
| 961 |
\mathbf{\nabla }_{h}\phi _{s}=\mathbf{\nabla }_{h}\left( b_{s}\eta \right) |
\mathbf{\nabla }_{h}\phi _{s}=\mathbf{\nabla }_{h}\left( b_{s}\eta \right) |
| 963 |
\end{equation} |
\end{equation} |
| 964 |
where $b_{s}$ is the buoyancy at the surface. |
where $b_{s}$ is the buoyancy at the surface. |
| 965 |
|
|
| 966 |
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 |
| 967 |
{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 |
| 968 |
elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free |
elliptic equation for $\phi _{s}$ as described in Chapter 2. Both `free |
| 969 |
surface' and `rigid lid' approaches are available. |
surface' and `rigid lid' approaches are available. |
| 970 |
|
|
| 971 |
\subsubsection{Non-hydrostatic pressure} |
\subsubsection{Non-hydrostatic pressure} |
| 972 |
|
|
| 973 |
Taking the horizontal divergence of (\ref{hor-mtm}) and adding $\frac{ |
Taking the horizontal divergence of (\ref{eq:mom-h}) and adding |
| 974 |
\partial }{\partial r}$ of (\ref{vertmtm}), invoking the continuity equation |
$\frac{\partial }{\partial r}$ of (\ref{eq:mom-w}), invoking the continuity equation |
| 975 |
(\ref{incompressible}), we deduce that: |
(\ref{eq:continuity}), we deduce that: |
| 976 |
|
|
| 977 |
\begin{equation} |
\begin{equation} |
| 978 |
\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{ |
| 1002 |
depending on the form chosen for the dissipative terms in the momentum |
depending on the form chosen for the dissipative terms in the momentum |
| 1003 |
equations - see below. |
equations - see below. |
| 1004 |
|
|
| 1005 |
Eq.(\ref{nonormalflow}) implies, making use of (\ref{mtm-split}), that: |
Eq.(\ref{nonormalflow}) implies, making use of (\ref{eq:mom-h}), that: |
| 1006 |
|
|
| 1007 |
\begin{equation} |
\begin{equation} |
| 1008 |
\widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}} |
\widehat{n}.\nabla \phi _{nh}=\widehat{n}.\vec{\mathbf{F}} |
| 1042 |
converges rapidly because $\phi _{nh}\ $is then only a small correction to |
converges rapidly because $\phi _{nh}\ $is then only a small correction to |
| 1043 |
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). |
| 1044 |
|
|
| 1045 |
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}) |
| 1046 |
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. |
| 1047 |
|
|
| 1048 |
\subsection{Forcing/dissipation} |
\subsection{Forcing/dissipation} |
| 1050 |
\subsubsection{Forcing} |
\subsubsection{Forcing} |
| 1051 |
|
|
| 1052 |
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 |
| 1053 |
`physics packages' described in detail in chapter ??. |
`physics packages' and forcing packages. These are described later on. |
| 1054 |
|
|
| 1055 |
\subsubsection{Dissipation} |
\subsubsection{Dissipation} |
| 1056 |
|
|
| 1071 |
|
|
| 1072 |
The mixing terms for the temperature and salinity equations have a similar |
The mixing terms for the temperature and salinity equations have a similar |
| 1073 |
form to that of momentum except that the diffusion tensor can be |
form to that of momentum except that the diffusion tensor can be |
| 1074 |
non-diagonal and have varying coefficients. $\qquad $ |
non-diagonal and have varying coefficients. |
| 1075 |
\begin{equation} |
\begin{equation} |
| 1076 |
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 |
| 1077 |
_{h}^{4}(T,S) \label{eq:diffusion} |
_{h}^{4}(T,S) \label{eq:diffusion} |
| 1097 |
|
|
| 1098 |
\subsection{Vector invariant form} |
\subsection{Vector invariant form} |
| 1099 |
|
|
| 1100 |
For some purposes it is advantageous to write momentum advection in eq(\ref |
For some purposes it is advantageous to write momentum advection in |
| 1101 |
{hor-mtm}) and (\ref{vertmtm}) in the (so-called) `vector invariant' form: |
eq(\ref {eq:horizontal_mtm}) and (\ref{eq:vertical_mtm}) in the |
| 1102 |
|
(so-called) `vector invariant' form: |
| 1103 |
|
|
| 1104 |
\begin{equation} |
\begin{equation} |
| 1105 |
\frac{D\vec{\mathbf{v}}}{Dt}=\frac{\partial \vec{\mathbf{v}}}{\partial t} |
\frac{D\vec{\mathbf{v}}}{Dt}=\frac{\partial \vec{\mathbf{v}}}{\partial t} |
| 1117 |
|
|
| 1118 |
\subsection{Adjoint} |
\subsection{Adjoint} |
| 1119 |
|
|
| 1120 |
Tangent linear and adjoint counterparts of the forward model and described |
Tangent linear and adjoint counterparts of the forward model are described |
| 1121 |
in Chapter 5. |
in Chapter 5. |
| 1122 |
|
|
|
% $Header$ |
|
|
% $Name$ |
|
|
|
|
| 1123 |
\section{Appendix ATMOSPHERE} |
\section{Appendix ATMOSPHERE} |
| 1124 |
|
|
| 1125 |
\subsection{Hydrostatic Primitive Equations for the Atmosphere in pressure |
\subsection{Hydrostatic Primitive Equations for the Atmosphere in pressure |
| 1139 |
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} |
| 1140 |
\end{eqnarray} |
\end{eqnarray} |
| 1141 |
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 |
| 1142 |
surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot |
surfaces) component of velocity, $\frac{D}{Dt}=\frac{\partial}{\partial t} |
| 1143 |
\mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total |
+\vec{\mathbf{v}}_{h}\cdot \mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ |
| 1144 |
derivative, $f=2\Omega \sin lat$ is the Coriolis parameter, $\phi =gz$ is |
is the total derivative, $f=2\Omega \sin \varphi$ is the Coriolis parameter, |
| 1145 |
the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp |
$\phi =gz$ is the geopotential, $\alpha =1/\rho $ is the specific volume, |
| 1146 |
}{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref |
$\omega =\frac{Dp }{Dt}$ is the vertical velocity in the $p-$coordinate. |
| 1147 |
{eq:atmos-heat}) is the first law of thermodynamics where internal energy $ |
Equation(\ref {eq:atmos-heat}) is the first law of thermodynamics where internal |
| 1148 |
e=c_{v}T$, $T$ is temperature, $Q$ is the rate of heating per unit mass and $ |
energy $e=c_{v}T$, $T$ is temperature, $Q$ is the rate of heating per unit mass |
| 1149 |
p\frac{D\alpha }{Dt}$ is the work done by the fluid in compressing. |
and $p\frac{D\alpha }{Dt}$ is the work done by the fluid in compressing. |
| 1150 |
|
|
| 1151 |
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 |
| 1152 |
$\theta $ so that it looks more like a generic conservation law. |
$\theta $ so that it looks more like a generic conservation law. |
| 1207 |
surface ($\phi $ is imposed and $\omega \neq 0$). |
surface ($\phi $ is imposed and $\omega \neq 0$). |
| 1208 |
|
|
| 1209 |
\subsubsection{Splitting the geo-potential} |
\subsubsection{Splitting the geo-potential} |
| 1210 |
|
\label{sec:hpe-p-geo-potential-split} |
| 1211 |
|
|
| 1212 |
For the purposes of initialization and reducing round-off errors, the model |
For the purposes of initialization and reducing round-off errors, the model |
| 1213 |
deals with perturbations from reference (or ``standard'') profiles. For |
deals with perturbations from reference (or ``standard'') profiles. For |
| 1237 |
The final form of the HPE's in p coordinates is then: |
The final form of the HPE's in p coordinates is then: |
| 1238 |
\begin{eqnarray} |
\begin{eqnarray} |
| 1239 |
\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}} |
| 1240 |
_{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} \\ |
_{h}+\mathbf{\nabla }_{p}\phi ^{\prime } &=&\vec{\mathbf{\mathcal{F}}} |
| 1241 |
|
\label{eq:atmos-prime} \\ |
| 1242 |
\frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\ |
\frac{\partial \phi ^{\prime }}{\partial p}+\alpha ^{\prime } &=&0 \\ |
| 1243 |
\mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{ |
\mathbf{\nabla }_{p}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial \omega }{ |
| 1244 |
\partial p} &=&0 \\ |
\partial p} &=&0 \\ |
| 1245 |
\frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\ |
\frac{\partial \Pi }{\partial p}\theta ^{\prime } &=&\alpha ^{\prime } \\ |
| 1246 |
\frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi } \label{eq:atmos-prime} |
\frac{D\theta }{Dt} &=&\frac{\mathcal{Q}}{\Pi } |
| 1247 |
\end{eqnarray} |
\end{eqnarray} |
| 1248 |
|
|
|
% $Header$ |
|
|
% $Name$ |
|
|
|
|
| 1249 |
\section{Appendix OCEAN} |
\section{Appendix OCEAN} |
| 1250 |
|
|
| 1251 |
\subsection{Equations of motion for the ocean} |
\subsection{Equations of motion for the ocean} |
| 1259 |
\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} |
| 1260 |
&=&\epsilon _{nh}\mathcal{F}_{w} \\ |
&=&\epsilon _{nh}\mathcal{F}_{w} \\ |
| 1261 |
\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}} |
| 1262 |
_{h}+\frac{\partial w}{\partial z} &=&0 \\ |
_{h}+\frac{\partial w}{\partial z} &=&0 \label{eq-zns-cont}\\ |
| 1263 |
\rho &=&\rho (\theta ,S,p) \\ |
\rho &=&\rho (\theta ,S,p) \label{eq-zns-eos}\\ |
| 1264 |
\frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\ |
\frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-zns-heat}\\ |
| 1265 |
\frac{DS}{Dt} &=&\mathcal{Q}_{s} \label{eq:non-boussinesq} |
\frac{DS}{Dt} &=&\mathcal{Q}_{s} \label{eq-zns-salt} |
| 1266 |
|
\label{eq:non-boussinesq} |
| 1267 |
\end{eqnarray} |
\end{eqnarray} |
| 1268 |
These equations permit acoustics modes, inertia-gravity waves, |
These equations permit acoustics modes, inertia-gravity waves, |
| 1269 |
non-hydrostatic motions, a geostrophic (Rossby) mode and a thermo-haline |
non-hydrostatic motions, a geostrophic (Rossby) mode and a thermohaline |
| 1270 |
mode. As written, they cannot be integrated forward consistently - if we |
mode. As written, they cannot be integrated forward consistently - if we |
| 1271 |
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 |
| 1272 |
consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref |
consistent with that obtained by stepping (\ref{eq-zns-heat}) and (\ref |
| 1281 |
_{\theta ,S}\frac{Dp}{Dt} \label{EOSexpansion} |
_{\theta ,S}\frac{Dp}{Dt} \label{EOSexpansion} |
| 1282 |
\end{equation} |
\end{equation} |
| 1283 |
|
|
| 1284 |
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 |
| 1285 |
reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref |
the reciprocal of the sound speed ($c_{s}$) squared. Substituting into |
| 1286 |
{eq-zns-cont} gives: |
\ref{eq-zns-cont} gives: |
| 1287 |
\begin{equation} |
\begin{equation} |
| 1288 |
\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{ |
| 1289 |
v}}+\partial _{z}w\approx 0 \label{eq-zns-pressure} |
v}}+\partial _{z}w\approx 0 \label{eq-zns-pressure} |
| 1460 |
_{nh}=0$ form of these equations that are used throughout the ocean modeling |
_{nh}=0$ form of these equations that are used throughout the ocean modeling |
| 1461 |
community and referred to as the primitive equations (HPE). |
community and referred to as the primitive equations (HPE). |
| 1462 |
|
|
|
% $Header$ |
|
|
% $Name$ |
|
|
|
|
| 1463 |
\section{Appendix:OPERATORS} |
\section{Appendix:OPERATORS} |
| 1464 |
|
|
| 1465 |
\subsection{Coordinate systems} |
\subsection{Coordinate systems} |
| 1470 |
and vertical direction respectively, are given by (see Fig.2) : |
and vertical direction respectively, are given by (see Fig.2) : |
| 1471 |
|
|
| 1472 |
\begin{equation*} |
\begin{equation*} |
| 1473 |
u=r\cos \phi \frac{D\lambda }{Dt} |
u=r\cos \varphi \frac{D\lambda }{Dt} |
| 1474 |
\end{equation*} |
\end{equation*} |
| 1475 |
|
|
| 1476 |
\begin{equation*} |
\begin{equation*} |
| 1477 |
v=r\frac{D\phi }{Dt}\qquad |
v=r\frac{D\varphi }{Dt} |
| 1478 |
\end{equation*} |
\end{equation*} |
|
$\qquad \qquad \qquad \qquad $ |
|
| 1479 |
|
|
| 1480 |
\begin{equation*} |
\begin{equation*} |
| 1481 |
\dot{r}=\frac{Dr}{Dt} |
\dot{r}=\frac{Dr}{Dt} |
| 1482 |
\end{equation*} |
\end{equation*} |
| 1483 |
|
|
| 1484 |
Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial |
Here $\varphi $ is the latitude, $\lambda $ the longitude, $r$ the radial |
| 1485 |
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 |
| 1486 |
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. |
| 1487 |
|
|
| 1488 |
The `grad' ($\nabla $) and `div' ($\nabla $.) operators are defined by, in |
The `grad' ($\nabla $) and `div' ($\nabla\cdot$) operators are defined by, in |
| 1489 |
spherical coordinates: |
spherical coordinates: |
| 1490 |
|
|
| 1491 |
\begin{equation*} |
\begin{equation*} |
| 1492 |
\nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda } |
\nabla \equiv \left( \frac{1}{r\cos \varphi }\frac{\partial }{\partial \lambda } |
| 1493 |
,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r} |
,\frac{1}{r}\frac{\partial }{\partial \varphi },\frac{\partial }{\partial r} |
| 1494 |
\right) |
\right) |
| 1495 |
\end{equation*} |
\end{equation*} |
| 1496 |
|
|
| 1497 |
\begin{equation*} |
\begin{equation*} |
| 1498 |
\nabla .v\equiv \frac{1}{r\cos \phi }\left\{ \frac{\partial u}{\partial |
\nabla\cdot v\equiv \frac{1}{r\cos \varphi }\left\{ \frac{\partial u}{\partial |
| 1499 |
\lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\} |
\lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\} |
| 1500 |
+\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} |
| 1501 |
\end{equation*} |
\end{equation*} |
| 1502 |
|
|