601 |
\left. |
\left. |
602 |
\begin{tabular}{l} |
\begin{tabular}{l} |
603 |
$G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\ |
$G_{u}=-\vec{\mathbf{v}}.\nabla u$ \\ |
604 |
$-\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\} $ |
605 |
\\ |
\\ |
606 |
$-\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\} $ |
607 |
\\ |
\\ |
608 |
$+\mathcal{F}_{u}$ |
$+\mathcal{F}_{u}$ |
609 |
\end{tabular} |
\end{tabular} |
621 |
\left. |
\left. |
622 |
\begin{tabular}{l} |
\begin{tabular}{l} |
623 |
$G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\ |
$G_{v}=-\vec{\mathbf{v}}.\nabla v$ \\ |
624 |
$-\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\} |
625 |
$ \\ |
$ \\ |
626 |
$-\left\{ -2\Omega u\sin lat\right\} $ \\ |
$-\left\{ -2\Omega u\sin \varphi \right\} $ \\ |
627 |
$+\mathcal{F}_{v}$ |
$+\mathcal{F}_{v}$ |
628 |
\end{tabular} |
\end{tabular} |
629 |
\ \right\} \left\{ |
\ \right\} \left\{ |
642 |
\begin{tabular}{l} |
\begin{tabular}{l} |
643 |
$G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\ |
$G_{\dot{r}}=-\underline{\underline{\vec{\mathbf{v}}.\nabla \dot{r}}}$ \\ |
644 |
$+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\ |
$+\left\{ \underline{\frac{u^{_{^{2}}}+v^{2}}{{r}}}\right\} $ \\ |
645 |
${+}\underline{{2\Omega u\cos lat}}$ \\ |
${+}\underline{{2\Omega u\cos \varphi}}$ \\ |
646 |
$\underline{\underline{\mathcal{F}_{\dot{r}}}}$ |
$\underline{\underline{\mathcal{F}_{\dot{r}}}}$ |
647 |
\end{tabular} |
\end{tabular} |
648 |
\ \right\} \left\{ |
\ \right\} \left\{ |
656 |
\end{equation} |
\end{equation} |
657 |
\qquad \qquad \qquad \qquad \qquad |
\qquad \qquad \qquad \qquad \qquad |
658 |
|
|
659 |
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 `$\varphi$ |
660 |
' is latitude. |
' is latitude. |
661 |
|
|
662 |
Grad and div operators in spherical coordinates are defined in appendix |
Grad and div operators in spherical coordinates are defined in appendix |
694 |
|
|
695 |
In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between |
In the `quasi-hydrostatic' equations (\textbf{QH)} strict balance between |
696 |
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 |
697 |
\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 |
698 |
contribution to the pressure field: only the terms underlined twice in Eqs. ( |
contribution to the pressure field: only the terms underlined twice in Eqs. ( |
699 |
\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 |
700 |
and, simultaneously, the shallow atmosphere approximation is relaxed. In |
and, simultaneously, the shallow atmosphere approximation is relaxed. In |
703 |
vertical momentum equation (\ref{eq:mom-w}) becomes: |
vertical momentum equation (\ref{eq:mom-w}) becomes: |
704 |
|
|
705 |
\begin{equation*} |
\begin{equation*} |
706 |
\frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos lat |
\frac{\partial \phi _{nh}}{\partial r}=2\Omega u\cos \varphi |
707 |
\end{equation*} |
\end{equation*} |
708 |
making a small correction to the hydrostatic pressure. |
making a small correction to the hydrostatic pressure. |
709 |
|
|
789 |
%%CNHend |
%%CNHend |
790 |
|
|
791 |
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 |
792 |
course, some complication that goes with the inclusion of $\cos \phi \ $ |
course, some complication that goes with the inclusion of $\cos \varphi \ $ |
793 |
Coriolis terms and the relaxation of the shallow atmosphere approximation. |
Coriolis terms and the relaxation of the shallow atmosphere approximation. |
794 |
But this leads to negligible increase in computation. In \textbf{NH}, in |
But this leads to negligible increase in computation. In \textbf{NH}, in |
795 |
contrast, one additional elliptic equation - a three-dimensional one - must |
contrast, one additional elliptic equation - a three-dimensional one - must |
1045 |
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 |
1046 |
surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot |
surfaces) component of velocity,$\frac{D}{Dt}=\vec{\mathbf{v}}_{h}\cdot |
1047 |
\mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total |
\mathbf{\nabla }_{p}+\omega \frac{\partial }{\partial p}$ is the total |
1048 |
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 |
1049 |
the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp |
the geopotential, $\alpha =1/\rho $ is the specific volume, $\omega =\frac{Dp |
1050 |
}{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref |
}{Dt}$ is the vertical velocity in the $p-$coordinate. Equation(\ref |
1051 |
{eq:atmos-heat}) is the first law of thermodynamics where internal energy $ |
{eq:atmos-heat}) is the first law of thermodynamics where internal energy $ |
1377 |
and vertical direction respectively, are given by (see Fig.2) : |
and vertical direction respectively, are given by (see Fig.2) : |
1378 |
|
|
1379 |
\begin{equation*} |
\begin{equation*} |
1380 |
u=r\cos \phi \frac{D\lambda }{Dt} |
u=r\cos \varphi \frac{D\lambda }{Dt} |
1381 |
\end{equation*} |
\end{equation*} |
1382 |
|
|
1383 |
\begin{equation*} |
\begin{equation*} |
1384 |
v=r\frac{D\phi }{Dt}\qquad |
v=r\frac{D\varphi }{Dt}\qquad |
1385 |
\end{equation*} |
\end{equation*} |
1386 |
$\qquad \qquad \qquad \qquad $ |
$\qquad \qquad \qquad \qquad $ |
1387 |
|
|
1389 |
\dot{r}=\frac{Dr}{Dt} |
\dot{r}=\frac{Dr}{Dt} |
1390 |
\end{equation*} |
\end{equation*} |
1391 |
|
|
1392 |
Here $\phi $ is the latitude, $\lambda $ the longitude, $r$ the radial |
Here $\varphi $ is the latitude, $\lambda $ the longitude, $r$ the radial |
1393 |
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 |
1394 |
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. |
1395 |
|
|
1397 |
spherical coordinates: |
spherical coordinates: |
1398 |
|
|
1399 |
\begin{equation*} |
\begin{equation*} |
1400 |
\nabla \equiv \left( \frac{1}{r\cos \phi }\frac{\partial }{\partial \lambda } |
\nabla \equiv \left( \frac{1}{r\cos \varphi }\frac{\partial }{\partial \lambda } |
1401 |
,\frac{1}{r}\frac{\partial }{\partial \phi },\frac{\partial }{\partial r} |
,\frac{1}{r}\frac{\partial }{\partial \varphi },\frac{\partial }{\partial r} |
1402 |
\right) |
\right) |
1403 |
\end{equation*} |
\end{equation*} |
1404 |
|
|
1405 |
\begin{equation*} |
\begin{equation*} |
1406 |
\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 |
1407 |
\lambda }+\frac{\partial }{\partial \phi }\left( v\cos \phi \right) \right\} |
\lambda }+\frac{\partial }{\partial \varphi }\left( v\cos \varphi \right) \right\} |
1408 |
+\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} |
1409 |
\end{equation*} |
\end{equation*} |
1410 |
|
|