249 lines
11 KiB
TeX
Executable File
249 lines
11 KiB
TeX
Executable File
\include{Preamble}
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\begin{document}
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\title{Draft description of NEMO wetting and drying scheme: 29 November 2017 }
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\author{ Enda O'Dea, Hedong Liu, Jason Holt, Andrew Coward and Michael J. Bell }
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%------------------------------------------------------------------------
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% End of temporary latex header (to be removed)
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%------------------------------------------------------------------------
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% ================================================================
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% Chapter Ocean Dynamics (DYN)
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% ================================================================
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\chapter{Ocean Dynamics (DYN)}
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\label{DYN}
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\minitoc
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% add a figure for dynvor ens, ene latices
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$\ $\newline % force a new ligne
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% ================================================================
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% Wetting and drying
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% ================================================================
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%----------------------------------------------------------------------------------------
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% The WAD test cases
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%----------------------------------------------------------------------------------------
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\section [The WAD test cases (\textit{usrdef\_zgr})]
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{The WAD test cases (\mdl{usrdef\_zgr})}
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\label{WAD_test_cases}
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This section contains details of the seven test cases that can be run as part of the
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WAD\_TEST\_CASES configuration. All the test cases are shallow (less than 10m deep),
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basins or channels with 4m high walls and some of topography that can wet and dry up to
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2.5m above sea-level. The horizontal grid is uniform with a 1km resolution and measures
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52km by 34km. These dimensions are determined by a combination of code in the
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\mdl{usrdef\_nam} module located in the WAD\_TEST\_CASES/MY\_SRC directory and setting
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read in from the namusr\_def namelist. The first six test cases are closed systems with no
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rotation or external forcing and motion is simply initiated by an initial ssh slope. The
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seventh test case introduces and open boundary at the right-hand end of the channel which
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is forced with sinousoidally varying ssh and barotropic velocities.
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\namdisplay{nam_wad_usr}
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The $\mathrm{nn\_wad\_test}$ parameter can takes values 1 to 7 and it is this parameter
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that determines which of the test cases will be run. Most cases can be run with the
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default settings but the simple linear slope cases (tests 1 and 5) can be run with lower
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values of $\mathrm{rn\_wdmin1}$. Any recommended changes to the default namelist settings
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will be stated in the individual subsections.
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Test case 7 requires additional {\tt namelist\_cfg} changes to activate the open boundary
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and lengthen the duration of the run (in order to demonstrate the full forcing cycle).
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There is also a simple python script which needs to be run in order to generate the
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boundary forcing files. Full details are given in subsection (\ref{WAD_test_case7}).
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\clearpage
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\subsection [WAD test case 1 : A simple linear slope]
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{WAD test case 1 : A simple linear slope}
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\label{WAD_test_case1}
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The first test case is a simple linear slope (in the x-direction, uniform in y) with an
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adverse SSH gradient that, when released, creates a surge up the slope. The parameters are
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chosen such that the surge rises above sea-level before falling back and oscillating
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towards an equilibrium position. This case can be run with $\mathrm{rn\_wdmin1}$ values as
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low as 0.075m. I.e. the following change may be made to the default values in {\tt
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namelist\_cfg} (for this test only):
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\namdisplay{nam_wad_tc1}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\begin{figure}[htb] \begin{center}
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\includegraphics[width=0.8\textwidth]{Fig_WAD_TC1}
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\caption{ \label{Fig_WAD_TC1}
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The evolution of the sea surface height in WAD\_TEST\_CASE 1 from the initial state (t=0)
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over the first three hours of simulation. Note that in this time-frame the resultant surge
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reaches to nearly 2m above sea-level before retreating.}
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\end{center}\end{figure}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\clearpage
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\subsection [WAD test case 2 : A parabolic channel ]
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{WAD test case 2 : A parabolic channel}
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\label{WAD_test_case2}
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The second and third test cases use a closed channel which is parabolic in x and uniform
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in y. Test case 2 uses a gentler initial SSH slope which nevertheless demonstrates the
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ability to wet and dry on both sides of the channel. This solution requires values of
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$\mathrm{rn\_wdmin1}$ at least 0.3m ({\it Q.: A function of the maximum topographic
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slope?})
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\namdisplay{nam_wad_tc2}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\begin{figure}[htb] \begin{center}
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\includegraphics[width=0.8\textwidth]{Fig_WAD_TC2}
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\caption{ \label{Fig_WAD_TC2}
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The evolution of the sea surface height in WAD\_TEST\_CASE 2 from the initial state (t=0)
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over the first three hours of simulation. Note that in this time-frame the resultant sloshing
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causes wetting and drying on both sides of the parabolic channel.}
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\end{center}\end{figure}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\clearpage
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\subsection [WAD test case 3 : A parabolic channel (extreme slope) ]
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{WAD test case 3 : A parabolic channel (extreme slope)}
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\label{WAD_test_case3}
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Similar to test case 2 but with a steeper initial SSH slope. The solution is similar but more vigorous.
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\namdisplay{nam_wad_tc3}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\begin{figure}[htb] \begin{center}
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\includegraphics[width=0.8\textwidth]{Fig_WAD_TC3}
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\caption{ \label{Fig_WAD_TC3}
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The evolution of the sea surface height in WAD\_TEST\_CASE 3 from the initial state (t=0)
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over the first three hours of simulation. Note that in this time-frame the resultant sloshing
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causes wetting and drying on both sides of the parabolic channel.}
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\end{center}\end{figure}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\clearpage
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\subsection [WAD test case 4 : A parabolic bowl ]
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{WAD test case 4 : A parabolic bowl}
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\label{WAD_test_case4}
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Test case 4 includes variation in the y-direction in the form of a parabolic bowl. The
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initial condition is now a raised bulge centred over the bowl. Figure \ref{Fig_WAD_TC4}
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shows a cross-section of the SSH in the X-direction but features can be seen to propagate
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in all directions and interfere when return paths cross.
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\namdisplay{nam_wad_tc4}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\begin{figure}[htb] \begin{center}
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\includegraphics[width=0.8\textwidth]{Fig_WAD_TC4}
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\caption{ \label{Fig_WAD_TC4}
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The evolution of the sea surface height in WAD\_TEST\_CASE 4 from the initial state (t=0)
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over the first three hours of simulation. Note that this test case is a parabolic bowl with
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variations occurring in the y-direction too (not shown here).}
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\end{center}\end{figure}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\clearpage
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\subsection [WAD test case 5 : A double slope with shelf channel ]
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{WAD test case 5 : A double slope with shelf channel}
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\label{WAD_test_case5}
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Similar in nature to test case 1 but with a change in slope and a mid-depth shelf.
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\namdisplay{nam_wad_tc5}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\begin{figure}[htb] \begin{center}
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\includegraphics[width=0.8\textwidth]{Fig_WAD_TC5}
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\caption{ \label{Fig_WAD_TC5}
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The evolution of the sea surface height in WAD\_TEST\_CASE 5 from the initial state (t=0)
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over the first three hours of simulation. The surge resulting in this case wets to the full
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depth permitted (2.5m above sea-level) and is only halted by the 4m high side walls.}
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\end{center}\end{figure}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\clearpage
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\subsection [WAD test case 6 : A parabolic channel with central bar ]
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{WAD test case 6 : A parabolic channel with central bar}
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\label{WAD_test_case6}
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Test cases 1 to 5 have all used uniform T and S conditions. The dashed line in each plot
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shows the surface salinity along the y=17 line which remains satisfactorily constant. Test
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case 6 introduces variation in salinity by taking a parabolic channel divided by a central
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bar (gaussian) and using two different salinity values in each half of the channel. This
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step change in salinity is initially enforced by the central bar but the bar is
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subsequently over-topped after the initial SSH gradient is released. The time series in
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this case shows the SSH evolution with the water coloured according to local salinity
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values. Encroachment of the high salinity (red) waters into the low salinity (blue) basin
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can clearly be seen.
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\namdisplay{nam_wad_tc6}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\begin{figure}[htb] \begin{center}
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\includegraphics[width=0.8\textwidth]{Fig_WAD_TC6}
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\caption{ \label{Fig_WAD_TC6}
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The evolution of the sea surface height in WAD\_TEST\_CASE 6 from the initial state (t=0)
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over the first three hours of simulation. Water is coloured according to local salinity
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values. Encroachment of the high salinity (red) waters into the low salinity (blue) basin
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can clearly be seen although the largest influx occurs early in the sequence between the
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frames shown.}
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\end{center}\end{figure}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\clearpage
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\subsection [WAD test case 7 : A double slope with shelf, open-ended channel ]
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{WAD test case 7 : A double slope with shelf, open-ended channel}
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\label{WAD_test_case7}
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Similar in nature to test case 5 but with an open boundary forced with a sinusoidally
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varying ssh. This test case has been introduced to emulate a typical coastal application
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with a tidally forced open boundary. The bathymetry and setup is identical to test case 5
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except the right hand end of the channel is now open and has simple ssh and barotropic
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velocity boundary conditions applied at the open boundary. Several additional steps and
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namelist changes are required to run this test.
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\namdisplay{nam_wad_tc7}
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In addition, the boundary condition files must be generated using the python script
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provided.
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\begin{verbatim}
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python ./makebdy_tc7.py
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\end{verbatim}
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will create the following boundary files for this test (assuming a suitably configured
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python environment: python2.7 with netCDF4 and numpy):
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\begin{verbatim}
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bdyssh_tc7_m12d30.nc bdyuv_tc7_m12d30.nc
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bdyssh_tc7_m01d01.nc bdyuv_tc7_m01d01.nc
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bdyssh_tc7_m01d02.nc bdyuv_tc7_m01d02.nc
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bdyssh_tc7_m01d03.nc bdyuv_tc7_m01d03.nc
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\end{verbatim}
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These are sufficient for up to a three day simulation; the script is easily adapted if
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longer periods are required.
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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\begin{sidewaysfigure}[htb] \begin{center}
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\includegraphics[width=0.8\textwidth]{Fig_WAD_TC7}
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\caption{ \label{Fig_WAD_TC7}
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The evolution of the sea surface height in WAD\_TEST\_CASE 7 from the initial state (t=0)
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over the first 24 hours of simulation. After the initial surge the solution settles into a
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simulated tidal cycle with an amplitude of 5m. This is enough to repeatedly wet and dry
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both shelves.}
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\end{center}\end{sidewaysfigure}
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%>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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% ================================================================
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%\bibliographystyle{wileyqj}
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%\bibliographystyle{../../../doc/latex/NEMO/main/ametsoc.bst}
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%\bibliography{references}
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\end{document}
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