Changeset 10614


Ignore:
Timestamp:
2019-01-31T18:10:55+01:00 (14 months ago)
Author:
smueller
Message:

Merge of changeset [10613] into the trunk

Location:
NEMO/trunk/doc/latex/NEMO
Files:
3 edited

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  • NEMO/trunk/doc/latex/NEMO/main/NEMO_manual.tex

    r10585 r10614  
    5050    Massimiliano Drudi, Christian Eth\'{e}, Simona Flavoni, Doroteaciro Iovino, Claire L\'{e}vy, Tomas Lovato, 
    5151    Nicolas Martin, S\'{e}bastien Masson, Pierre Mathiot, Gelsomina Mattia, Francesca Mele, Silvia Mocavero, 
    52     George Nurser, Enda O'Dea, Julien Paul, Cl\'{e}ment Rousset, Dave Storkey, Martin Vancoppenolle 
     52    Simon M\"{u}ller, George Nurser, Enda O'Dea, Julien Paul, Cl\'{e}ment Rousset, Dave Storkey, 
     53    Martin Vancoppenolle 
    5354  }                                                        \\ 
    5455                                                           \\ 
  • NEMO/trunk/doc/latex/NEMO/subfiles/chap_LBC.tex

    r10530 r10614  
    711711%----------------------------------------------------------------------------------------------- 
    712712 
    713 Options are defined through the \ngn{nambdy\_tide} namelist variables  
    714 for reading in the complex harmonic amplitudes of elevation (ssh) and barotropic velocity (u,v).  
    715  
    716 The tidal harmonic data can be specified in 2 ways.\\ 
    717 First it can be specified on a 2D grid covering the entire model domain in which case the user should set \np{ln\_bdytide\_2ddta }\forcode{ = .true.}.  
    718 In this case the model assumes that the real and imaginary parts are split. 
    719 The variable naming convention is \textit{constituent\_name\_z1} for real SSH and \textit{constituent\_name\_z2} for imaginary SSH.  
    720 The available \textit{constituent\_names} in NEMO are defined in \rou{SBC/tide.h90} 
    721 Likewise for $u$ and $v$ data. File name is assumed to be \np{filtide}\ifile{\_grid\_T} for the elevation component  
    722 and \np{filtide}\ifile{\_grid\_U} for the u barotropic velocity and \np{filtide}\ifile{\_grid\_V} for the v barotropic velocity.\\  
    723 Otherwise, the tidal data must be specified along bdy segments.  
    724 In this case each constituent has its own file name and the real part is assumed to be z1 and the imaginary part z2 for SSH.  
    725 Similarly u1, u2 and v1, v2 for velocities. Input file name convention (for elevation of the M2 tidal component) is \np{filtide}\ifile{M2\_grid\_T}.  
    726 Similar logic applies for other components and u and v barotropic velocities.\\ 
    727  
    728 The data may also be in complex conjugate form. If that is the case then the user should set \np{ln\_bdytide\_conj}\forcode{ = .true. }  
    729 so the model correctly interprets the data. The default case assumes it is not in complex conjugate form.  
    730  
    731 Note the barotropic velocities are assumed to be on the model native grid and must be rotated as appropriate from the source grid upon which they are extracted from.  
    732 To do so convert to U, V amplitude and phase into tidal ellipses. Add the grid rotation to ellipse inclination and convert back. Be careful about conventions  
    733 of direction of rotation, e.g. anticlockwise or clockwise.  
     713Tidal forcing at open boundaries requires the activation of surface 
     714tides (i.e., in \ngn{nam\_tide}, \np{ln\_tide} needs to be set to 
     715\forcode{.true.} and the required constituents need to be activated by 
     716including their names in the \np{cname} array; see 
     717\autoref{sec:SBC_tide}). Specific options related to the reading in of 
     718the complex harmonic amplitudes of elevation (SSH) and barotropic 
     719velocity (u,v) at open boundaries are defined through the 
     720\ngn{nambdy\_tide} namelist parameters.\\ 
     721 
     722The tidal harmonic data at open boundaries can be specified in two 
     723different ways, either on a two-dimensional grid covering the entire 
     724model domain or along open boundary segments; these two variants can 
     725be selected by setting \np{ln\_bdytide\_2ddta } to \forcode{.true.} or 
     726\forcode{.false.}, respectively. In either case, the real and 
     727imaginary parts of SSH and the two barotropic velocity components for 
     728each activated tidal constituent \textit{tcname} have to be provided 
     729separately: when two-dimensional data is used, variables 
     730\textit{tcname\_z1} and \textit{tcname\_z2} for real and imaginary SSH, 
     731respectively, are expected in input file \np{filtide} with suffix 
     732\ifile{\_grid\_T}, variables \textit{tcname\_u1} and 
     733\textit{tcname\_u2} for real and imaginary u, respectively, are 
     734expected in input file \np{filtide} with suffix \ifile{\_grid\_U}, and 
     735\textit{tcname\_v1} and \textit{tcname\_v2} for real and imaginary v, 
     736respectively, are expected in input file \np{filtide} with suffix 
     737\ifile{\_grid\_V}; when data along open boundary segments is used, 
     738variables \textit{z1} and \textit{z2} (real and imaginary part of SSH) 
     739are expected to be available from file \np{filtide} with suffix 
     740\ifile{tcname\_grid\_T}, variables \textit{u1} and \textit{u2} (real 
     741and imaginary part of u) are expected to be available from file 
     742\np{filtide} with suffix \ifile{tcname\_grid\_U}, and variables 
     743\textit{v1} and \textit{v2} (real and imaginary part of v) are 
     744expected to be available from file \np{filtide} with suffix 
     745\ifile{tcname\_grid\_V}. If \np{ln\_bdytide\_conj} is set to 
     746\forcode{.true.}, the data is expected to be in complex conjugate 
     747form. 
     748 
     749Note that the barotropic velocity components are assumed to be defined 
     750on the native model grid and should be rotated accordingly when they 
     751are converted from their definition on a different source grid. To do 
     752so, the u, v amplitudes and phases can be converted into tidal 
     753ellipses, the grid rotation added to the ellipse inclination, and then 
     754converted back (care should be taken regarding conventions of the 
     755direction of rotation). %, e.g. anticlockwise or clockwise. 
    734756 
    735757\biblio 
  • NEMO/trunk/doc/latex/NEMO/subfiles/chap_SBC.tex

    r10468 r10614  
    815815 
    816816The tidal forcing, generated by the gravity forces of the Earth-Moon and Earth-Sun sytems, 
    817 is activated if \np{ln\_tide} and \np{ln\_tide\_pot} are both set to \np{.true.} in \ngn{nam\_tide}. 
     817is activated if \np{ln\_tide} and \np{ln\_tide\_pot} are both set to \forcode{.true.} in \ngn{nam\_tide}. 
    818818This translates as an additional barotropic force in the momentum equations \ref{eq:PE_dyn} such that: 
    819819\[ 
     
    822822  +g\nabla (\Pi_{eq} + \Pi_{sal}) 
    823823\] 
    824 where $\Pi_{eq}$ stands for the equilibrium tidal forcing and $\Pi_{sal}$ a self-attraction and loading term (SAL).  
     824where $\Pi_{eq}$ stands for the equilibrium tidal forcing and 
     825$\Pi_{sal}$ is a self-attraction and loading term (SAL). 
    825826  
    826 The equilibrium tidal forcing is expressed as a sum over the chosen constituents $l$ in \ngn{nam\_tide}. 
    827 The constituents are defined such that \np{clname(1) = 'M2', clname(2)='S2', etc...}. 
    828 For the three types of tidal frequencies it reads: \\ 
    829 Long period tides : 
    830 \[ 
    831   \Pi_{eq}(l)=A_{l}(1+k-h)(\frac{1}{2}-\frac{3}{2}sin^{2}\phi)cos(\omega_{l}t+V_{l}) 
    832 \] 
    833 diurnal tides : 
    834 \[ 
    835   \Pi_{eq}(l)=A_{l}(1+k-h)(sin 2\phi)cos(\omega_{l}t+\lambda+V_{l}) 
    836 \] 
    837 Semi-diurnal tides: 
    838 \[ 
    839   \Pi_{eq}(l)=A_{l}(1+k-h)(cos^{2}\phi)cos(\omega_{l}t+2\lambda+V_{l}) 
    840 \] 
    841 Here $A_{l}$ is the amplitude, $\omega_{l}$ is the frequency, $\phi$ the latitude, $\lambda$ the longitude, 
    842 $V_{0l}$ a phase shift with respect to Greenwich meridian and $t$ the time. 
    843 The Love number factor $(1+k-h)$ is here taken as a constant (0.7). 
    844  
    845 The SAL term should in principle be computed online as it depends on the model tidal prediction itself 
    846 (see \citet{Arbic2004} for a discussion about the practical implementation of this term). 
    847 Nevertheless, the complex calculations involved would make this computationally too expensive. 
    848 Here, practical solutions are whether to read complex estimates $\Pi_{sal}(l)$ from an external model 
    849 (\np{ln\_read\_load=.true.}) or use a ``scalar approximation'' (\np{ln\_scal\_load=.true.}). 
    850 In the latter case, it reads:\\ 
    851 \[ 
    852   \Pi_{sal} = \beta \eta 
    853 \] 
    854 where $\beta$ (\np{rn\_scal\_load}, $\approx0.09$) is a spatially constant scalar, 
    855 often chosen to minimize tidal prediction errors. 
    856 Setting both \np{ln\_read\_load} and \np{ln\_scal\_load} to false removes the SAL contribution. 
     827The equilibrium tidal forcing is expressed as a sum over a subset of 
     828constituents chosen from the set of available tidal constituents 
     829defined in file \rou{SBC/tide.h90} (this comprises the tidal 
     830constituents \textit{M2, N2, 2N2, S2, K2, K1, O1, Q1, P1, M4, Mf, Mm, 
     831  Msqm, Mtm, S1, MU2, NU2, L2}, and \textit{T2}). Individual 
     832constituents are selected by including their names in the array 
     833\np{clname} in \ngn{nam\_tide} (e.g., \np{clname(1) = 'M2', 
     834  clname(2)='S2'} to select solely the tidal consituents \textit{M2} 
     835and \textit{S2}). Optionally, when \np{ln\_tide\_ramp} is set to 
     836\forcode{.true.}, the equilibrium tidal forcing can be ramped up 
     837linearly from zero during the initial \np{rdttideramp} days of the 
     838model run. 
     839 
     840The SAL term should in principle be computed online as it depends on 
     841the model tidal prediction itself (see \citet{Arbic2004} for a 
     842discussion about the practical implementation of this term). 
     843Nevertheless, the complex calculations involved would make this 
     844computationally too expensive.  Here, two options are available: 
     845$\Pi_{sal}$ generated by an external model can be read in 
     846(\np{ln\_read\_load=.true.}), or a ``scalar approximation'' can be 
     847used (\np{ln\_scal\_load=.true.}). In the latter case 
     848\[ 
     849  \Pi_{sal} = \beta \eta, 
     850\] 
     851where $\beta$ (\np{rn\_scal\_load} with a default value of 0.094) is a 
     852spatially constant scalar, often chosen to minimize tidal prediction 
     853errors. Setting both \np{ln\_read\_load} and \np{ln\_scal\_load} to 
     854\forcode{.false.} removes the SAL contribution. 
    857855 
    858856% ================================================================ 
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