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 20190131T17:38:13+01:00 (4 years ago)
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NEMO/releases/release4.0/doc/latex/NEMO/subfiles/chap_LBC.tex
r10530 r10613 711 711 % 712 712 713 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. 713 Tidal forcing at open boundaries requires the activation of surface 714 tides (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 716 including their names in the \np{cname} array; see 717 \autoref{sec:SBC_tide}). Specific options related to the reading in of 718 the complex harmonic amplitudes of elevation (SSH) and barotropic 719 velocity (u,v) at open boundaries are defined through the 720 \ngn{nambdy\_tide} namelist parameters.\\ 721 722 The tidal harmonic data at open boundaries can be specified in two 723 different ways, either on a twodimensional grid covering the entire 724 model domain or along open boundary segments; these two variants can 725 be selected by setting \np{ln\_bdytide\_2ddta } to \forcode{.true.} or 726 \forcode{.false.}, respectively. In either case, the real and 727 imaginary parts of SSH and the two barotropic velocity components for 728 each activated tidal constituent \textit{tcname} have to be provided 729 separately: when twodimensional data is used, variables 730 \textit{tcname\_z1} and \textit{tcname\_z2} for real and imaginary SSH, 731 respectively, 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 734 expected in input file \np{filtide} with suffix \ifile{\_grid\_U}, and 735 \textit{tcname\_v1} and \textit{tcname\_v2} for real and imaginary v, 736 respectively, are expected in input file \np{filtide} with suffix 737 \ifile{\_grid\_V}; when data along open boundary segments is used, 738 variables \textit{z1} and \textit{z2} (real and imaginary part of SSH) 739 are expected to be available from file \np{filtide} with suffix 740 \ifile{tcname\_grid\_T}, variables \textit{u1} and \textit{u2} (real 741 and 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 744 expected 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 747 form. 748 749 Note that the barotropic velocity components are assumed to be defined 750 on the native model grid and should be rotated accordingly when they 751 are converted from their definition on a different source grid. To do 752 so, the u, v amplitudes and phases can be converted into tidal 753 ellipses, the grid rotation added to the ellipse inclination, and then 754 converted back (care should be taken regarding conventions of the 755 direction of rotation). %, e.g. anticlockwise or clockwise. 734 756 735 757 \biblio
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