--- manual/s_overview/appendix_ocean.tex 2001/09/11 14:39:38 1.2 +++ manual/s_overview/appendix_ocean.tex 2001/09/27 01:57:17 1.3 @@ -1,4 +1,4 @@ -% $Header: /home/ubuntu/mnt/e9_copy/manual/s_overview/Attic/appendix_ocean.tex,v 1.2 2001/09/11 14:39:38 cnh Exp $ +% $Header: /home/ubuntu/mnt/e9_copy/manual/s_overview/Attic/appendix_ocean.tex,v 1.3 2001/09/27 01:57:17 cnh Exp $ % $Name: $ \section{Appendix OCEAN} @@ -9,12 +9,12 @@ HPE's for the ocean written in z-coordinates are obtained. The non-Boussinesq equations for oceanic motion are: \begin{eqnarray} -\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}} _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \\ \epsilon _{nh}\frac{Dw}{Dt}+g+\frac{1}{\rho }\frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w} \\ -\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}} _{h}+\frac{\partial w}{\partial z} &=&0 \\ \rho &=&\rho (\theta ,S,p) \\ \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \\ @@ -41,7 +41,7 @@ reciprocal of the sound speed ($c_{s}$) squared. Substituting into \ref {eq-zns-cont} gives: \begin{equation} -\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{ v}}+\partial _{z}w\approx 0 \label{eq-zns-pressure} \end{equation} where we have used an approximation sign to indicate that we have assumed @@ -49,12 +49,12 @@ Replacing \ref{eq-zns-cont} with \ref{eq-zns-pressure} yields a system that can be explicitly integrated forward: \begin{eqnarray} -\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}} _{h}+\frac{1}{\rho }\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \label{eq-cns-hmom} \\ \epsilon _{nh}\frac{Dw}{Dt}+g+\frac{1}{\rho }\frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w} \label{eq-cns-hydro} \\ -\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{ v}}_{h}+\frac{\partial w}{\partial z} &=&0 \label{eq-cns-cont} \\ \rho &=&\rho (\theta ,S,p) \label{eq-cns-eos} \\ \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-cns-heat} \\ @@ -68,13 +68,13 @@ `Boussinesq assumption'. The only term that then retains the full variation in $\rho $ is the gravitational acceleration: \begin{eqnarray} -\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}} _{h}+\frac{1}{\rho _{o}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \label{eq-zcb-hmom} \\ -\epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}}% +\epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}} \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w} \label{eq-zcb-hydro} \\ -\frac{1}{\rho _{o}c_{s}^{2}}\frac{Dp}{Dt}+\mathbf{\nabla }_{z}\cdot \vec{% +\frac{1}{\rho _{o}c_{s}^{2}}\frac{Dp}{Dt}+\mathbf{\nabla }_{z}\cdot \vec{ \mathbf{v}}_{h}+\frac{\partial w}{\partial z} &=&0 \label{eq-zcb-cont} \\ \rho &=&\rho (\theta ,S,p) \label{eq-zcb-eos} \\ \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-zcb-heat} \\ @@ -86,14 +86,14 @@ term appears as a Helmholtz term in the non-hydrostatic pressure equation). These are the \emph{truly} compressible Boussinesq equations. Note that the EOS must have the same pressure dependency as the linearized pressure term, -ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{% +ie. $\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}=\frac{1}{ c_{s}^{2}}$, for consistency. \subsubsection{`Anelastic' z-coordinate equations} The anelastic approximation filters the acoustic mode by removing the -time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont}% -). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o}% +time-dependency in the continuity (now pressure-) equation (\ref{eq-zcb-cont} +). This could be done simply by noting that $\frac{Dp}{Dt}\approx -g\rho _{o} \frac{Dz}{Dt}=-g\rho _{o}w$, but this leads to an inconsistency between continuity and EOS. A better solution is to change the dependency on pressure in the EOS by splitting the pressure into a reference function of @@ -104,29 +104,29 @@ Remembering that the term $\frac{Dp}{Dt}$ in continuity comes from differentiating the EOS, the continuity equation then becomes: \[ -\frac{1}{\rho _{o}c_{s}^{2}}\left( \frac{Dp_{o}}{Dt}+\epsilon _{s}\frac{% -Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+% +\frac{1}{\rho _{o}c_{s}^{2}}\left( \frac{Dp_{o}}{Dt}+\epsilon _{s}\frac{ +Dp^{\prime }}{Dt}\right) +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+ \frac{\partial w}{\partial z}=0 \] If the time- and space-scales of the motions of interest are longer than -those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt},% +those of acoustic modes, then $\frac{Dp^{\prime }}{Dt}<<(\frac{Dp_{o}}{Dt}, \mathbf{\nabla }\cdot \vec{\mathbf{v}}_{h})$ in the continuity equations and -$\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{% +$\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{ Dp^{\prime }}{Dt}<<\left. \frac{\partial \rho }{\partial p}\right| _{\theta ,S}\frac{Dp_{o}}{Dt}$ in the EOS (\ref{EOSexpansion}). Thus we set $\epsilon _{s}=0$, removing the dependency on $p^{\prime }$ in the continuity equation and EOS. Expanding $\frac{Dp_{o}(z)}{Dt}=-g\rho _{o}w$ then leads to the anelastic continuity equation: \begin{equation} -\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}-% +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z}- \frac{g}{c_{s}^{2}}w=0 \label{eq-za-cont1} \end{equation} A slightly different route leads to the quasi-Boussinesq continuity equation -where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+% -\mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla }% +where we use the scaling $\frac{\partial \rho ^{\prime }}{\partial t}+ +\mathbf{\nabla }_{3}\cdot \rho ^{\prime }\vec{\mathbf{v}}<<\mathbf{\nabla } _{3}\cdot \rho _{o}\vec{\mathbf{v}}$ yielding: \begin{equation} -\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{% +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{ \partial \left( \rho _{o}w\right) }{\partial z}=0 \label{eq-za-cont2} \end{equation} Equations \ref{eq-za-cont1} and \ref{eq-za-cont2} are in fact the same @@ -135,18 +135,18 @@ \frac{1}{\rho _{o}}\frac{\partial \rho _{o}}{\partial z}=\frac{-g}{c_{s}^{2}} \end{equation} Again, note that if $\rho _{o}$ is evaluated from prescribed $\theta _{o}$ -and $S_{o}$ profiles, then the EOS dependency on $p_{o}$ and the term $\frac{% +and $S_{o}$ profiles, then the EOS dependency on $p_{o}$ and the term $\frac{ g}{c_{s}^{2}}$ in continuity should be referred to those same profiles. The full set of `quasi-Boussinesq' or `anelastic' equations for the ocean are then: \begin{eqnarray} -\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}} _{h}+\frac{1}{\rho _{o}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \label{eq-zab-hmom} \\ -\epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}}% +\epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{o}}+\frac{1}{\rho _{o}} \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w} \label{eq-zab-hydro} \\ -\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{% +\mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{1}{\rho _{o}}\frac{ \partial \left( \rho _{o}w\right) }{\partial z} &=&0 \label{eq-zab-cont} \\ \rho &=&\rho (\theta ,S,p_{o}(z)) \label{eq-zab-eos} \\ \frac{D\theta }{Dt} &=&\mathcal{Q}_{\theta } \label{eq-zab-heat} \\ @@ -159,10 +159,10 @@ technically, to also remove the dependence of $\rho $ on $p_{o}$. This would yield the ``truly'' incompressible Boussinesq equations: \begin{eqnarray} -\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}} _{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p &=&\vec{\mathbf{\mathcal{F}}} \label{eq-ztb-hmom} \\ -\epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{c}}+\frac{1}{\rho _{c}}% +\epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho }{\rho _{c}}+\frac{1}{\rho _{c}} \frac{\partial p}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w} \label{eq-ztb-hydro} \\ \mathbf{\nabla }_{z}\cdot \vec{\mathbf{v}}_{h}+\frac{\partial w}{\partial z} @@ -193,8 +193,8 @@ This then yields what we can call the semi-compressible Boussinesq equations: \begin{eqnarray} -\frac{D\vec{\mathbf{v}}_{h}}{Dt}+f\hat{\mathbf{k}}\times \vec{\mathbf{v}}% -_{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{% +\frac{D\vec{\mathbf{v}}_{h}}{Dt}+f\hat{\mathbf{k}}\times \vec{\mathbf{v}} +_{h}+\frac{1}{\rho _{c}}\mathbf{\nabla }_{z}p^{\prime } &=&\vec{\mathbf{ \mathcal{F}}} \label{eq:ocean-mom} \\ \epsilon _{nh}\frac{Dw}{Dt}+\frac{g\rho ^{\prime }}{\rho _{c}}+\frac{1}{\rho _{c}}\frac{\partial p^{\prime }}{\partial z} &=&\epsilon _{nh}\mathcal{F}_{w}