1 | % ================================================================ |
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2 | % Chapter Ñ Configurations |
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3 | % ================================================================ |
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4 | \chapter{Configurations} |
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5 | \label{MISC} |
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6 | \minitoc |
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7 | |
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8 | \newpage |
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9 | $\ $\newline % force a new ligne |
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10 | |
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11 | % ================================================================ |
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12 | % Introduction |
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13 | % ================================================================ |
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14 | \section{Introduction} |
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15 | \label{CFG_intro} |
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16 | |
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17 | |
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18 | The purpose of this part of the manual is to introduce the \NEMO predefined configuration. |
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19 | These configurations are offered as means to explore various numerical and physical options, |
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20 | thus allowing the user to verify that the code is performing in a manner consistent with that |
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21 | we are running. This form of verification is critical as one adopts the code for his or her particular |
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22 | research purposes. The test cases also provide a sense for some of the options available |
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23 | in the code, though by no means are all options exercised in the predefined configurations. |
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24 | |
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25 | |
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26 | %There is several predefined ocean configuration which use is controlled by a specific CPP key. |
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27 | |
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28 | %The key set the domain sizes (\jp{jpiglo}, \jp{jpjglo}, \jp{jpk}), the mesh and the bathymetry, |
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29 | %and, in some cases, add to the model physics some specific treatments. |
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30 | |
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31 | |
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32 | % ================================================================ |
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33 | % 1D model functionality |
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34 | % ================================================================ |
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35 | \section{Water column model: 1D model (\key{c1d})} |
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36 | \label{CFG_c1d} |
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37 | |
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38 | The 1D model option simulates a stand alone water column within the 3D \NEMO system. |
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39 | It can be applied to the ocean alone or to the ocean-ice system and can include passive tracers |
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40 | or a biogeochemical model. It is set up by defining the \key{c1d} CPP key. |
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41 | The 1D model is a very useful tool |
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42 | \textit{(a)} to learn about the physics and numerical treatment of vertical mixing processes ; |
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43 | \textit{(b)} to investigate suitable parameterisations of unresolved turbulence (wind steering, |
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44 | langmuir circulation, skin layers, ...) ; |
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45 | \textit{(c)} to compare the behaviour of different vertical mixing schemes ; |
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46 | \textit{(d)} to perform sensitivity studies on the vertical diffusion at a particular point of an ocean domain ; |
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47 | \textit{(d)} to produce extra diagnostics, without the large memory requirement of the full 3D model. |
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48 | |
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49 | The methodology is based on the use of the zoom functionality over the smallest possible |
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50 | domain : a 3 x 3 domain centred on the grid point of interest (see \S\ref{MISC_zoom}), |
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51 | with some extra routines. There is no need to define a new mesh, bathymetry, |
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52 | initial state or forcing, since the 1D model will use those of the configuration it is a zoom of. |
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53 | The chosen grid point is set in par\_oce.F90 module by setting the jpizoom and jpjzoom |
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54 | parameters to the indices of the location of the chosen grid point. |
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55 | |
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56 | |
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57 | % ================================================================ |
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58 | % ORCA family configurations |
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59 | % ================================================================ |
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60 | \section{ORCA family: global ocean with tripolar grid} |
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61 | \label{CFG_orca} |
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62 | |
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63 | The ORCA family is a series of global ocean configurations that are run together with |
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64 | the LIM sea-ice model (ORCA-LIM) and possibly with PISCES biogeochemical model |
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65 | (ORCA-LIM-PISCES), using various resolutions. |
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66 | |
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67 | % ------------------------------------------------------------------------------------------------------------- |
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68 | % ORCA tripolar grid |
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69 | % ------------------------------------------------------------------------------------------------------------- |
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70 | \subsection{ORCA tripolar grid} |
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71 | \label{CFG_orca_grid} |
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72 | |
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73 | The ORCA grid is a tripolar is based on the semi-analytical method of \citet{Madec_Imbard_CD96}. |
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74 | It allows to construct a global orthogonal curvilinear ocean mesh which has no singularity point inside |
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75 | the computational domain since two north mesh poles are introduced and placed on lands. |
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76 | The method involves defining an analytical set of mesh parallels in the stereographic polar plan, |
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77 | computing the associated set of mesh meridians, and projecting the resulting mesh onto the sphere. |
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78 | The set of mesh parallels used is a series of embedded ellipses which foci are the two mesh north |
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79 | poles (Fig.~\ref{Fig_MISC_ORCA_msh}). The resulting mesh presents no loss of continuity in |
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80 | either the mesh lines or the scale factors, or even the scale factor derivatives over the whole |
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81 | ocean domain, as the mesh is not a composite mesh. |
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82 | |
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83 | The method is applied to Mercator grid ($i.e.$ same zonal and meridional grid spacing) poleward |
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84 | of $20\deg$N, so that the Equator is a mesh line, which provides a better numerical solution |
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85 | for equatorial dynamics. The choice of the series of embedded ellipses (position of the foci and |
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86 | variation of the ellipses) is a compromise between maintaining the ratio of mesh anisotropy |
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87 | ($e_1 / e_2$) close to one in the ocean (especially in area of strong eddy activities such as |
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88 | the Gulf Stream) and keeping the smallest scale factor in the northern hemisphere larger |
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89 | than the smallest one in the southern hemisphere. |
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90 | The resulting mesh is shown in Fig.~\ref{Fig_MISC_ORCA_msh} and \ref{Fig_MISC_ORCA_e1e2} |
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91 | for a half a degree grid (ORCA\_R05). The smallest ocean scale factor is found in along |
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92 | Antarctica, while the ratio of anisotropy remains close to one except near the Victoria Island |
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93 | in the Canadian Archipelago. |
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94 | |
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95 | |
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96 | %>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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97 | \begin{figure}[!t] \begin{center} |
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98 | \includegraphics[width=0.98\textwidth]{./TexFiles/Figures/Fig_ORCA_NH_mesh.pdf} |
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99 | \caption{ \label{Fig_MISC_ORCA_msh} |
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100 | ORCA mesh conception. The departure from an isotropic Mercator grid start poleward of 20\deg N. |
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101 | The two "north pole" are the foci of a series of embedded ellipses (blue curves) |
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102 | which are determined analytically and form the i-lines of the ORCA mesh (pseudo latitudes). |
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103 | Then, following \citet{Madec_Imbard_CD96}, the normal to the series of ellipses (red curves) is computed |
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104 | which provide the j-lines of the mesh (pseudo longitudes). } |
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105 | \end{center} \end{figure} |
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106 | %>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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107 | |
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108 | |
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109 | %>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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110 | \begin{figure}[!tbp] \begin{center} |
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111 | \includegraphics[width=1.0\textwidth]{./TexFiles/Figures/Fig_ORCA_NH_msh05_e1_e2.pdf} |
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112 | \includegraphics[width=0.80\textwidth]{./TexFiles/Figures/Fig_ORCA_aniso.pdf} |
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113 | \caption { \label{Fig_MISC_ORCA_e1e2} |
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114 | \textit{Top}: Horizontal scale factors ($e_1$, $e_2$) and |
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115 | \textit{Bottom}: ratio of anisotropy ($e_1 / e_2$) |
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116 | for ORCA 0.5\deg ~mesh. South of 20\deg N a Mercator grid is used ($e_1 = e_2$) |
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117 | so that the anisotropy ratio is 1. Poleward of 20\deg N, the two "north pole" |
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118 | introduce a weak anisotropy over the ocean areas ($< 1.2$) except in vicinity of Victoria Island |
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119 | (Canadian Arctic Archipelago). } |
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120 | \end{center} \end{figure} |
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121 | %>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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122 | |
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123 | |
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124 | |
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125 | % ------------------------------------------------------------------------------------------------------------- |
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126 | % ORCA-LIM(-PISCES) configurations |
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127 | % ------------------------------------------------------------------------------------------------------------- |
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128 | \subsection{ORCA-LIM(-PISCES) configurations} |
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129 | \label{CFG_orca_grid} |
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130 | |
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131 | |
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132 | The NEMO system is provided with four built-in ORCA configurations which differ in the |
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133 | horizontal resolution |
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134 | \footnote{the value of the resolution is given by the resolution at the Equator expressed in degrees.} |
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135 | used: |
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136 | \begin{description} |
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137 | \item[\key{orca\_r4}] \jp{cp\_cfg}~=~orca ; \jp{jp\_cfg}~=~4 |
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138 | \item[\key{orca\_r2}] \jp{cp\_cfg}~=~orca ; \jp{jp\_cfg}~=~2 |
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139 | %\item[\key{orca\_r1}] \jp{cp\_cfg}~=~orca ; \jp{jp\_cfg}~=~1 |
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140 | \item[\key{orca\_r05}] \jp{cp\_cfg}~=~orca ; \jp{jp\_cfg}~=~05 |
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141 | \item[\key{orca\_r025}] \jp{cp\_cfg}~=~orca ; \jp{jp\_cfg}~=~025 |
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142 | \end{description} |
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143 | |
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144 | The ORCA\_R2 configuration has the following specificity : starting from a 2\deg~ORCA mesh, |
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145 | local mesh refinements were applied to the Mediterranean, Red, Black and Caspian Seas, |
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146 | so that the resolution is $1\deg \time 1\deg$ there. A local transformation were also applied |
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147 | with in the Tropics in order to refine the meridional resolution up to 0.5\deg at the Equator. |
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148 | |
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149 | The ORCA\_R1 configuration has only a local tropical transformation to refine the meridional |
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150 | resolution up to 1/3\deg~at the Equator. Note that the tropical mesh refinements in ORCA\_R2 |
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151 | and R1 strongly increases the mesh anisotropy there. |
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152 | |
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153 | The ORCA\_R05 configuration and higher ones does not incorporate any regional refinements. |
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154 | |
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155 | Only the ORCA\_R2 is provided with all its input files in the \NEMO distribution. |
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156 | It is very similar to that used as part of the climate model developed at IPSL for the 4th IPCC |
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157 | assessment of climate change (Marti et al., 2009). It is also the basis for the \NEMO contribution |
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158 | to the Coordinate Ocean-ice Reference Experiments (COREs) documented in \citet{Griffies_al_OM09}. |
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159 | |
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160 | This version of ORCA\_R2 has 31 levels in the vertical, with the highest resolution (10m) |
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161 | in the upper 150m. The bottom topography and the coastlines are derived |
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162 | from the global atlas of Smith and Sandwell (1997). The default forcing employ the boundary |
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163 | forcing from \citet{Large_Yeager_Rep04} (see \S\ref{SBC_blk_core}), |
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164 | which was developed for the purpose of running global coupled ocean-ice simulations |
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165 | without an interactive atmosphere. This \citet{Large_Yeager_Rep04} dataset is available |
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166 | through the GFDL web site \footnote{http://nomads.gfdl.noaa.gov/nomads/forms/mom4/CORE.html}. |
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167 | The "normal year" of \citet{Large_Yeager_Rep04} has been chosen of the \NEMO distribution |
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168 | since release v3.3. |
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169 | |
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170 | The vertical resolution can be increased by a factor of 10 by defining the \key{orca\_lev10} CPP key. |
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171 | It can also be run with an AGRIF zoom over the Agulhas current area ( \key{agrif} defined). |
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172 | Also available are to keys, \key{arctic} and \key{antarctic}, which allows to run a regional Arctic |
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173 | or peri-Antarctic configuration extracted from an ORCA configuration. (This does not work with ORCA\_R4 and R1). |
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174 | |
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175 | |
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176 | %--------------------------------------------------TABLE-------------------------------------------------- |
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177 | \begin{table}[htbp] \begin{center} |
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178 | \begin{tabular}{ccccc} |
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179 | key & \jp{jp\_cfg} & \jp{jpiglo} & \jp{jpiglo} & \\ |
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180 | \hline \hline |
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181 | \key{orca\_r4} & 4 & 92 & 76 & \\ |
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182 | \key{orca\_r2} & 2 & 182 & 149 & \\ |
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183 | %\key{orca\_r1} & 1 & 362 & 511 & \\ |
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184 | \key{orca\_r05} & 05 & 722 & 261 & \\ |
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185 | \key{orca\_r025} & 025 & 1442 & 1021 & \\ |
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186 | %\key{orca\_r8} & 8 & 2882 & 2042 & \\ |
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187 | %\key{orca\_r12} & 12 & 4322 & 3062 & \\ |
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188 | \hline |
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189 | \hline |
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190 | \end{tabular} |
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191 | \caption{ \label{Tab_ORCA} |
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192 | Set of predefined ORCA parameters. } |
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193 | \end{center} |
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194 | \end{table} |
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195 | %-------------------------------------------------------------------------------------------------------------- |
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196 | |
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197 | |
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198 | % ------------------------------------------------------------------------------------------------------------- |
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199 | % GYRE family: double gyre basin |
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200 | % ------------------------------------------------------------------------------------------------------------- |
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201 | \section{GYRE family: double gyre basin (\key{gyre})} |
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202 | \label{MISC_config_gyre} |
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203 | |
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204 | The GYRE configuration \citep{Levy_al_OM10} have been built to simulated |
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205 | the seasonal cycle of a double-gyre box model. It consist in an idealized domain |
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206 | similar to that used in the studies of \citet{Drijfhout_JPO94} and \citet{Hazeleger_Drijfhout_JPO98, |
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207 | Hazeleger_Drijfhout_JPO99, Hazeleger_Drijfhout_JGR00, Hazeleger_Drijfhout_JPO00}, |
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208 | over which an analytical seasonal forcing is applied. This allows to investigate the |
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209 | spontaneous generation of a large number of interacting, transient mesoscale eddies |
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210 | and their contribution to the large scale circulation. |
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211 | |
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212 | The domain geometry is a closed rectangular basin on the $\beta$-plane centred |
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213 | at $\sim 30\deg$N and rotated by 45\deg, 3180~km long, 2120~km wide |
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214 | and 4~km deep (Fig.~\ref{Fig_MISC_strait_hand}). |
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215 | The domain is bounded by vertical walls and by a ßat bottom. The configuration is |
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216 | meant to represent an idealized North Atlantic or North Pacific basin. |
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217 | The circulation is forced by analytical profiles of wind and buoyancy ßuxes. |
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218 | The applied forcings vary seasonally in a sinusoidal manner between winter |
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219 | and summer extrema \citep{Levy_al_OM10}. |
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220 | The wind stress is zonal and its curl changes sign at 22\deg N and 36\deg N. |
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221 | It forces a subpolar gyre in the north, a subtropical gyre in the wider part of the domain |
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222 | and a small recirculation gyre in the southern corner. |
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223 | The net heat ßux takes the form of a restoring toward a zonal apparent air |
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224 | temperature profile. A portion of the net heat ßux which comes from the solar radiation |
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225 | is allowed to penetrate within the water column. |
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226 | The fresh water ßux is also prescribed and varies zonally. |
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227 | It is determined such as, at each time step, the basin-integrated ßux is zero. |
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228 | The basin is initialised at rest with vertical profiles of temperature and salinity |
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229 | uniformly applied to the whole domain. |
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230 | |
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231 | The GYRE configuration is set through the \key{gyre} CPP key. Its horizontal resolution |
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232 | (and thus the size of the domain) is determined by setting \jp{jp\_cfg} in \hf{par\_GYRE} file: \\ |
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233 | \jp{jpiglo} $= 30 \times$ \jp{jp\_cfg} + 2 \\ |
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234 | \jp{jpjglo} $= 20 \times$ \jp{jp\_cfg} + 2 \\ |
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235 | Obviously, the namelist parameters have to be adjusted to the chosen resolution. |
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236 | In the vertical, GYRE uses the default 30 ocean levels (\jp{jpk}=31) (Fig.~\ref{Fig_zgr}). |
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237 | |
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238 | The GYRE configuration is also used in benchmark test as it is very simple to increase |
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239 | its resolution and as it does not requires any input file. For example, keeping a same model size |
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240 | on each processor while increasing the number of processor used is very easy, even though the |
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241 | physical integrity of the solution can be compromised. |
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242 | |
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243 | %>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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244 | \begin{figure}[!t] \begin{center} |
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245 | \includegraphics[width=1.0\textwidth]{./TexFiles/Figures/Fig_GYRE.pdf} |
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246 | \caption{ \label{Fig_GYRE} |
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247 | Snapshot of relative vorticity at the surface of the model domain |
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248 | in GYRE R9, R27 and R54. From \citet{Levy_al_OM10}.} |
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249 | \end{center} \end{figure} |
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250 | %>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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251 | |
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252 | % ------------------------------------------------------------------------------------------------------------- |
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253 | % EEL family configuration |
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254 | % ------------------------------------------------------------------------------------------------------------- |
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255 | \section{EEL family: periodic channel} |
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256 | \label{MISC_config_EEL} |
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257 | |
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258 | \begin{description} |
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259 | \item[\key{eel\_r2}] to be described.... |
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260 | \item[\key{eel\_r5}] |
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261 | \item[\key{eel\_r6}] |
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262 | \end{description} |
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263 | |
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264 | % ------------------------------------------------------------------------------------------------------------- |
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265 | % POMME configuration |
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266 | % ------------------------------------------------------------------------------------------------------------- |
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267 | \section{POMME: mid-latitude sub-domain} |
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268 | \label{MISC_config_POMME} |
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269 | |
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270 | |
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271 | \key{pomme\_r025} : to be described.... |
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272 | |
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273 | |
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274 | |
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