Changeset 994 for trunk/DOC/TexFiles/Chapters/Chap_DYN.tex
- Timestamp:
- 2008-05-28T11:01:09+02:00 (16 years ago)
- Location:
- trunk/DOC/TexFiles
- Files:
-
- 1 copied
- 1 moved
Legend:
- Unmodified
- Added
- Removed
-
trunk/DOC/TexFiles/Chapters/Chap_DYN.tex
r817 r994 107 107 \left\{ 108 108 \begin{aligned} 109 { -\frac{1}{e_{1u} } } & {\overline {\left( { \frac{\zeta +f}{e_{3f} }} \right)} }^{\,i} & {\overline{\overline {\left( {e_{1v} e_{3v} v} \right)}} }^{\,i, j+1/2} \\110 { +\frac{1}{e_{2v} } } & {\overline {\left( {\frac{\zeta +f}{e_{3f} }} \right)} }^{\,j} & {\overline{\overline {\left( {e_{2u} e_{3u} u} \right)}} }^{\,i+1/2, j}109 {+\frac{1}{e_{1u} } } & {\overline {\left( { \frac{\zeta +f}{e_{3f} }} \right)} }^{\,i} & {\overline{\overline {\left( {e_{1v} e_{3v} v} \right)}} }^{\,i, j+1/2} \\ 110 {-\frac{1}{e_{2v} } } & {\overline {\left( {\frac{\zeta +f}{e_{3f} }} \right)} }^{\,j} & {\overline{\overline {\left( {e_{2u} e_{3u} u} \right)}} }^{\,i+1/2, j} 111 111 \end{aligned} 112 112 \right. … … 124 124 \left\{ { 125 125 \begin{aligned} 126 { -\frac{1}{e_{1u} }\; {\overline {\left( {\frac{\zeta +f}{e_{3f} }} \right)126 {+\frac{1}{e_{1u} }\; {\overline {\left( {\frac{\zeta +f}{e_{3f} }} \right) 127 127 \;\overline {\left( {e_{1v} e_{3v} v} \right)} ^{\,i+1/2}} }^{\,j} } \\ 128 { +\frac{1}{e_{2v} }\; {\overline {\left( {\frac{\zeta +f}{e_{3f} }} \right)128 {-\frac{1}{e_{2v} }\; {\overline {\left( {\frac{\zeta +f}{e_{3f} }} \right) 129 129 \;\overline {\left( {e_{2u} e_{3u} u} \right)} ^{\,j+1/2}} }^{\,i} } 130 130 \end{aligned} … … 145 145 \left\{ { 146 146 \begin{aligned} 147 { -\frac{1}{e_{1u} }\; {\overline {\left( {\frac{\zeta }{e_{3f} }} \right)} }^{\,i}147 {+\frac{1}{e_{1u} }\; {\overline {\left( {\frac{\zeta }{e_{3f} }} \right)} }^{\,i} 148 148 \; {\overline{\overline {\left( {e_{1v} \; e_{3v} \ v} \right)}} }^{\,i,j+1/2} -\frac{1}{e_{1u} } 149 149 \; {\overline {\left( {\frac{f}{e_{3f} }} \right) 150 150 \;\overline {\left( {e_{1v} \; e_{3v} \ v} \right)} ^{\,i+1/2}} }^{\,j} } \\ 151 { +\frac{1}{e_{2v} }\; {\overline {\left( {\frac{\zeta }{e_{3f} }} \right)} }^j151 {-\frac{1}{e_{2v} }\; {\overline {\left( {\frac{\zeta }{e_{3f} }} \right)} }^j 152 152 \; {\overline{\overline {\left( {e_{2u} \; e_{3u} \ u} \right)}} }^{\,i+1/2,j} +\frac{1}{e_{2v} } 153 153 \; {\overline {\left( {\frac{f}{e_{3f} }} \right) … … 220 220 -q\,e_3 \,u &\equiv -\frac{1}{e_{2v} } \left[ 221 221 {{\begin{array}{*{20}c} 222 {\,\ \ a_{j-1/2}^{i } \left( {e_{2u} e_{3 v} \ u} \right)_{j+1}^{i+1/2} }223 {\,+\,b_{j-1/2}^{i+1} \left( {e_{2u} e_{3 v} \ u} \right)_{j+1/2}^{i+1} } \\222 {\,\ \ a_{j-1/2}^{i } \left( {e_{2u} e_{3u} \ u} \right)_{j+1}^{i+1/2} } 223 {\,+\,b_{j-1/2}^{i+1} \left( {e_{2u} e_{3u} \ u} \right)_{j+1/2}^{i+1} } \\ 224 224 \\ 225 { +\,c_{j+1/2}^{i+1} \left( {e_{2u} e_{3 v} \ u} \right)_{j+1/2}^{i+1} }226 {\,+\,d_{j+1/2}^{i } \left( {e_{2u} e_{3 v} \ u} \right)_{j+1/2}^{i } } \\225 { +\,c_{j+1/2}^{i+1} \left( {e_{2u} e_{3u} \ u} \right)_{j+1/2}^{i+1} } 226 {\,+\,d_{j+1/2}^{i } \left( {e_{2u} e_{3u} \ u} \right)_{j+1/2}^{i } } \\ 227 227 \end{array} }} \right] 228 228 \end{aligned} … … 670 670 \right]+\delta _j \left[ {e_{1v} e_{3v} v} \right]} \right)} 671 671 \end{equation} 672 673 where EMP is the surface freshwater budget, expressed in $Kg.m^{-2}.s^{-1}$,674 and $\rho _w =1,000\,Kg.m^{-3}$ is the volumic mass of pure water. If river675 runoff is expressed as a surface freshwater flux, see \S\ref{SBC}, then EMP676 can be written as the evaporation minus precipitation, minus the river runoff.677 The sea-surface height is evaluated using a leapfrog scheme in combination678 with an Asselin time filter, $i.e.$ the velocity appearing in679 \eqref{Eq_dynspg_ssh} is centred in time(\textit{now} velocity).672 where EMP is the surface freshwater budget, expressed in Kg/m$^2$/s 673 (which is equal to mm/s), and $\rho _w$=1,000~Kg/m$^3$ is the volumic 674 mass of pure water. If river runoff is expressed as a surface freshwater flux 675 (see \S\ref{SBC}) then EMP can be written as the evaporation minus 676 precipitation, minus the river runoff. The sea-surface height is evaluated 677 using a leapfrog scheme in combination with an Asselin time filter, $i.e.$ 678 the velocity appearing in \eqref{Eq_dynspg_ssh} is centred in time 679 (\textit{now} velocity). 680 680 681 681 The surface pressure gradient, also evaluated using a leap-frog scheme, is … … 683 683 \begin{equation} \label{Eq_dynspg_exp} 684 684 \left\{ \begin{aligned} 685 - \frac{1} {e_{1u}} \; \delta _{i+1/2} \left[ \,\eta\, \right] \\ 686 \\ 687 - \frac{1} {e_{2v}} \; \delta _{j+1/2} \left[ \,\eta\, \right] 685 - \frac{1}{e_{1u}} \; \delta _{i+1/2} \left[ \,\eta\, \right] \\ 686 - \frac{1}{e_{2v}} \; \delta _{j+1/2} \left[ \,\eta\, \right] 688 687 \end{aligned} \right. 689 688 \end{equation} … … 704 703 proposed by \citet{Griffies2004}. The general idea is to solve the free surface 705 704 equation with a small time step \np{rdtbt}, while the three dimensional 706 prognostic variables are solved with a longer time step that is a multiple of \np{rdtbt}707 (Fig.\ref {Fig_DYN_dynspg_ts}).705 prognostic variables are solved with a longer time step that is a multiple of 706 \np{rdtbt} (Fig.\ref {Fig_DYN_dynspg_ts}). 708 707 709 708 %> > > > > > > > > > > > > > > > > > > > > > > > > > > > … … 711 710 \begin{center} 712 711 \includegraphics[width=0.90\textwidth]{./Figures/Fig_DYN_dynspg_ts.pdf} 713 \caption{Schematic of the split-explicit time stepping scheme for the barotropic714 and baroclinic modes, after \citet{Griffies2004}. Time increases to the right.715 Baroclinic time steps are denoted by $t-\Delta t$, $t, t+\Delta t$, and $t+2\Delta t$.716 The curved line represents a leap-frog time step, and the smaller barotropic time717 steps $N \Delta t=2\Delta t$ are denoted by the zig-zag line. The vertically718 integrated forcing \textbf{M}(t) computed at the baroclinic time step $t$719 represents the interaction between the barotropic and baroclinic motions.720 While keeping the total depth, tracer, and freshwater forcing fields fixed, a721 leap-frog integration carries the surface height and vertically integrated velocity722 from $t$ to $t+2 \Delta t$ using N barotropic time steps of length $\Delta t$.723 Time averaging the barotropic fields over the N+1time steps (endpoints724 included) centers the vertically integrated velocity a t the baroclinic timestep725 $t+\Delta t$. A baroclinic leap-frog time step carries the surface height to712 \caption{Schematic of the split-explicit time stepping scheme for the external 713 and internal modes. Time increases to the right. 714 Internal mode time steps (which are also the model time steps) are denoted 715 by $t-\Delta t$, $t, t+\Delta t$, and $t+2\Delta t$. 716 The curved line represents a leap-frog time step, and the smaller time 717 steps $N \Delta t_e=\frac{3}{2}\Delta t$ are denoted by the zig-zag line. The vertically 718 integrated forcing \textbf{M}(t) computed at the model time step $t$ 719 represents the interaction between the external and internal motions. 720 While keeping \textbf{M} and freshwater forcing field fixed, a 721 leap-frog integration carries the external mode variables (surface height and vertically integrated velocity) from $t$ to $t+\frac{3}{2} \Delta t$ using N external time steps of length $\Delta t_e$. 722 Time averaging the external fields over the $\frac{2}{3}N+1$ time steps (endpoints 723 included) centers the vertically integrated velocity and the sea surface height at the model timestep $t+\Delta t$. These averaged values are used to update \textbf{M}(t) with both the surface pressure gradient and the Coriolis force. 724 A baroclinic leap-frog time step carries the surface height to The model time stepping scheme can then be achieved by 726 725 $t+\Delta t$ using the convergence of the time averaged vertically integrated 727 726 velocity taken from baroclinic time step t. }
Note: See TracChangeset
for help on using the changeset viewer.