Changeset 10414 for NEMO/trunk/doc/latex/NEMO/subfiles/chap_TRA.tex
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NEMO/trunk/doc/latex/NEMO/subfiles/chap_TRA.tex
r10406 r10414 1 \documentclass[../tex_main/NEMO_manual]{subfiles} 1 \documentclass[../main/NEMO_manual]{subfiles} 2 2 3 \begin{document} 3 4 % ================================================================ … … 6 7 \chapter{Ocean Tracers (TRA)} 7 8 \label{chap:TRA} 9 8 10 \minitoc 9 11 … … 14 16 15 17 %\newpage 16 \vspace{2.cm}17 %$\ $\newline % force a new ligne18 18 19 19 Using the representation described in \autoref{chap:DOM}, … … 28 28 Their prognostic equations can be summarized as follows: 29 29 \[ 30 \text{NXT} = \text{ADV}+\text{LDF}+\text{ZDF}+\text{SBC}31 30 \text{NXT} = \text{ADV}+\text{LDF}+\text{ZDF}+\text{SBC} 31 \ (+\text{QSR})\ (+\text{BBC})\ (+\text{BBL})\ (+\text{DMP}) 32 32 \] 33 33 … … 59 59 (\np{ln\_tra\_trd} or \np{ln\_tra\_mxl}\forcode{ = .true.}), as described in \autoref{chap:DIA}. 60 60 61 $\ $\newline % force a new ligne62 61 % ================================================================ 63 62 % Tracer Advection … … 74 73 $i.e.$ as the divergence of the advective fluxes. 75 74 Its discrete expression is given by : 76 \begin{equation} \label{eq:tra_adv} 77 ADV_\tau =-\frac{1}{b_t} \left( 78 \;\delta_i \left[ e_{2u}\,e_{3u} \; u\; \tau_u \right] 79 +\delta_j \left[ e_{1v}\,e_{3v} \; v\; \tau_v \right] \; \right) 80 -\frac{1}{e_{3t}} \;\delta_k \left[ w\; \tau_w \right] 75 \begin{equation} 76 \label{eq:tra_adv} 77 ADV_\tau =-\frac{1}{b_t} \left( 78 \;\delta_i \left[ e_{2u}\,e_{3u} \; u\; \tau_u \right] 79 +\delta_j \left[ e_{1v}\,e_{3v} \; v\; \tau_v \right] \; \right) 80 -\frac{1}{e_{3t}} \;\delta_k \left[ w\; \tau_w \right] 81 81 \end{equation} 82 82 where $\tau$ is either T or S, and $b_t= e_{1t}\,e_{2t}\,e_{3t}$ is the volume of $T$-cells. … … 95 95 \begin{center} 96 96 \includegraphics[width=0.9\textwidth]{Fig_adv_scheme} 97 \caption{ \protect\label{fig:adv_scheme} 97 \caption{ 98 \protect\label{fig:adv_scheme} 98 99 Schematic representation of some ways used to evaluate the tracer value at $u$-point and 99 100 the amount of tracer exchanged between two neighbouring grid points. … … 193 194 the two neighbouring $T$-point values. 194 195 For example, in the $i$-direction : 195 \begin{equation} \label{eq:tra_adv_cen2} 196 \tau_u^{cen2} =\overline T ^{i+1/2} 196 \begin{equation} 197 \label{eq:tra_adv_cen2} 198 \tau_u^{cen2} =\overline T ^{i+1/2} 197 199 \end{equation} 198 200 … … 212 214 a $4^{th}$ order interpolation, and thus depend on the four neighbouring $T$-points. 213 215 For example, in the $i$-direction: 214 \begin{equation} \label{eq:tra_adv_cen4}215 \tau_u^{cen4} 216 =\overline{ T - \frac{1}{6}\,\delta_i \left[ \delta_{i+1/2}[T] \,\right] }^{\,i+1/2}216 \begin{equation} 217 \label{eq:tra_adv_cen4} 218 \tau_u^{cen4} =\overline{ T - \frac{1}{6}\,\delta_i \left[ \delta_{i+1/2}[T] \,\right] }^{\,i+1/2} 217 219 \end{equation} 218 220 In the vertical direction (\np{nn\_cen\_v}\forcode{ = 4}), … … 258 260 a centred scheme. 259 261 For example, in the $i$-direction : 260 \begin{equation} \label{eq:tra_adv_fct} 261 \begin{split} 262 \tau_u^{ups}&= \begin{cases} 263 T_{i+1} & \text{if $\ u_{i+1/2} < 0$} \hfill \\ 264 T_i & \text{if $\ u_{i+1/2} \geq 0$} \hfill \\ 265 \end{cases} \\ 266 \\ 267 \tau_u^{fct}&=\tau_u^{ups} +c_u \;\left( {\tau_u^{cen} -\tau_u^{ups} } \right) 268 \end{split} 262 \begin{equation} 263 \label{eq:tra_adv_fct} 264 \begin{split} 265 \tau_u^{ups}&= 266 \begin{cases} 267 T_{i+1} & \text{if $\ u_{i+1/2} < 0$} \hfill \\ 268 T_i & \text{if $\ u_{i+1/2} \geq 0$} \hfill \\ 269 \end{cases} 270 \\ \\ 271 \tau_u^{fct}&=\tau_u^{ups} +c_u \;\left( {\tau_u^{cen} -\tau_u^{ups} } \right) 272 \end{split} 269 273 \end{equation} 270 274 where $c_u$ is a flux limiter function taking values between 0 and 1. … … 305 309 two $T$-points (\autoref{fig:adv_scheme}). 306 310 For example, in the $i$-direction : 307 \begin{equation} \label{eq:tra_adv_mus} 308 \tau_u^{mus} = \left\{ \begin{aligned} 309 &\tau_i &+ \frac{1}{2} \;\left( 1-\frac{u_{i+1/2} \;\rdt}{e_{1u}} \right) 310 &\ \widetilde{\partial _i \tau} & \quad \text{if }\;u_{i+1/2} \geqslant 0 \\ 311 &\tau_{i+1/2} &+\frac{1}{2}\;\left( 1+\frac{u_{i+1/2} \;\rdt}{e_{1u} } \right) 312 &\ \widetilde{\partial_{i+1/2} \tau } & \text{if }\;u_{i+1/2} <0 313 \end{aligned} \right. 314 \end{equation} 311 \[ 312 % \label{eq:tra_adv_mus} 313 \tau_u^{mus} = \left\{ 314 \begin{aligned} 315 &\tau_i &+ \frac{1}{2} \;\left( 1-\frac{u_{i+1/2} \;\rdt}{e_{1u}} \right) 316 &\ \widetilde{\partial _i \tau} & \quad \text{if }\;u_{i+1/2} \geqslant 0 \\ 317 &\tau_{i+1/2} &+\frac{1}{2}\;\left( 1+\frac{u_{i+1/2} \;\rdt}{e_{1u} } \right) 318 &\ \widetilde{\partial_{i+1/2} \tau } & \text{if }\;u_{i+1/2} <0 319 \end{aligned} 320 \right. 321 \] 315 322 where $\widetilde{\partial _i \tau}$ is the slope of the tracer on which a limitation is imposed to 316 323 ensure the \textit{positive} character of the scheme. … … 338 345 It is an upstream-biased third order scheme based on an upstream-biased parabolic interpolation. 339 346 For example, in the $i$-direction: 340 \begin{equation} \label{eq:tra_adv_ubs} 341 \tau_u^{ubs} =\overline T ^{i+1/2}-\;\frac{1}{6} \left\{ 342 \begin{aligned} 343 &\tau"_i & \quad \text{if }\ u_{i+1/2} \geqslant 0 \\ 344 &\tau"_{i+1} & \quad \text{if }\ u_{i+1/2} < 0 345 \end{aligned} \right. 347 \begin{equation} 348 \label{eq:tra_adv_ubs} 349 \tau_u^{ubs} =\overline T ^{i+1/2}-\;\frac{1}{6} \left\{ 350 \begin{aligned} 351 &\tau"_i & \quad \text{if }\ u_{i+1/2} \geqslant 0 \\ 352 &\tau"_{i+1} & \quad \text{if }\ u_{i+1/2} < 0 353 \end{aligned} 354 \right. 346 355 \end{equation} 347 356 where $\tau "_i =\delta_i \left[ {\delta_{i+1/2} \left[ \tau \right]} \right]$. … … 373 382 374 383 Note that it is straightforward to rewrite \autoref{eq:tra_adv_ubs} as follows: 375 \begin{equation} \label{eq:traadv_ubs2} 376 \tau_u^{ubs} = \tau_u^{cen4} + \frac{1}{12} \left\{ 377 \begin{aligned} 378 & + \tau"_i & \quad \text{if }\ u_{i+1/2} \geqslant 0 \\ 379 & - \tau"_{i+1} & \quad \text{if }\ u_{i+1/2} < 0 380 \end{aligned} \right. 381 \end{equation} 384 \[ 385 \label{eq:traadv_ubs2} 386 \tau_u^{ubs} = \tau_u^{cen4} + \frac{1}{12} \left\{ 387 \begin{aligned} 388 & + \tau"_i & \quad \text{if }\ u_{i+1/2} \geqslant 0 \\ 389 & - \tau"_{i+1} & \quad \text{if }\ u_{i+1/2} < 0 390 \end{aligned} 391 \right. 392 \] 382 393 or equivalently 383 \begin{equation} \label{eq:traadv_ubs2b} 384 u_{i+1/2} \ \tau_u^{ubs} 385 =u_{i+1/2} \ \overline{ T - \frac{1}{6}\,\delta_i\left[ \delta_{i+1/2}[T] \,\right] }^{\,i+1/2} 386 - \frac{1}{2} |u|_{i+1/2} \;\frac{1}{6} \;\delta_{i+1/2}[\tau"_i] 387 \end{equation} 394 \[ 395 % \label{eq:traadv_ubs2b} 396 u_{i+1/2} \ \tau_u^{ubs} 397 =u_{i+1/2} \ \overline{ T - \frac{1}{6}\,\delta_i\left[ \delta_{i+1/2}[T] \,\right] }^{\,i+1/2} 398 - \frac{1}{2} |u|_{i+1/2} \;\frac{1}{6} \;\delta_{i+1/2}[\tau"_i] 399 \] 388 400 389 401 \autoref{eq:traadv_ubs2} has several advantages. … … 519 531 520 532 The laplacian diffusion operator acting along the model (\textit{i,j})-surfaces is given by: 521 \begin{equation} \label{eq:tra_ldf_lap} 522 D_t^{lT} =\frac{1}{b_t} \left( \; 523 \delta_{i}\left[ A_u^{lT} \; \frac{e_{2u}\,e_{3u}}{e_{1u}} \;\delta_{i+1/2} [T] \right] 524 + \delta_{j}\left[ A_v^{lT} \; \frac{e_{1v}\,e_{3v}}{e_{2v}} \;\delta_{j+1/2} [T] \right] \;\right) 533 \begin{equation} 534 \label{eq:tra_ldf_lap} 535 D_t^{lT} =\frac{1}{b_t} \left( \; 536 \delta_{i}\left[ A_u^{lT} \; \frac{e_{2u}\,e_{3u}}{e_{1u}} \;\delta_{i+1/2} [T] \right] 537 + \delta_{j}\left[ A_v^{lT} \; \frac{e_{1v}\,e_{3v}}{e_{2v}} \;\delta_{j+1/2} [T] \right] \;\right) 525 538 \end{equation} 526 539 where $b_t$=$e_{1t}\,e_{2t}\,e_{3t}$ is the volume of $T$-cells and … … 554 567 \subsubsection{Standard rotated (bi-)laplacian operator (\protect\mdl{traldf\_iso})} 555 568 \label{subsec:TRA_ldf_iso} 569 556 570 The general form of the second order lateral tracer subgrid scale physics (\autoref{eq:PE_zdf}) 557 571 takes the following semi-discrete space form in $z$- and $s$-coordinates: 558 \begin{equation} \label{eq:tra_ldf_iso} 559 \begin{split} 560 D_T^{lT} = \frac{1}{b_t} & \left\{ \,\;\delta_i \left[ A_u^{lT} \left( 561 \frac{e_{2u}\,e_{3u}}{e_{1u}} \,\delta_{i+1/2}[T] 562 - e_{2u}\;r_{1u} \,\overline{\overline{ \delta_{k+1/2}[T] }}^{\,i+1/2,k} 563 \right) \right] \right. \\ 564 & +\delta_j \left[ A_v^{lT} \left( 565 \frac{e_{1v}\,e_{3v}}{e_{2v}} \,\delta_{j+1/2} [T] 566 - e_{1v}\,r_{2v} \,\overline{\overline{ \delta_{k+1/2} [T] }}^{\,j+1/2,k} 567 \right) \right] \\ 568 & +\delta_k \left[ A_w^{lT} \left( 569 -\;e_{2w}\,r_{1w} \,\overline{\overline{ \delta_{i+1/2} [T] }}^{\,i,k+1/2} 570 \right. \right. \\ 571 & \qquad \qquad \quad 572 - e_{1w}\,r_{2w} \,\overline{\overline{ \delta_{j+1/2} [T] }}^{\,j,k+1/2} \\ 573 & \left. {\left. { \qquad \qquad \ \ \ \left. { 574 +\;\frac{e_{1w}\,e_{2w}}{e_{3w}} \,\left( r_{1w}^2 + r_{2w}^2 \right) 575 \,\delta_{k+1/2} [T] } \right) } \right] \quad } \right\} 576 \end{split} 572 \begin{equation} 573 \label{eq:tra_ldf_iso} 574 \begin{split} 575 D_T^{lT} = \frac{1}{b_t} & \left\{ \,\;\delta_i \left[ A_u^{lT} \left( 576 \frac{e_{2u}\,e_{3u}}{e_{1u}} \,\delta_{i+1/2}[T] 577 - e_{2u}\;r_{1u} \,\overline{\overline{ \delta_{k+1/2}[T] }}^{\,i+1/2,k} 578 \right) \right] \right. \\ 579 & +\delta_j \left[ A_v^{lT} \left( 580 \frac{e_{1v}\,e_{3v}}{e_{2v}} \,\delta_{j+1/2} [T] 581 - e_{1v}\,r_{2v} \,\overline{\overline{ \delta_{k+1/2} [T] }}^{\,j+1/2,k} 582 \right) \right] \\ 583 & +\delta_k \left[ A_w^{lT} \left( 584 -\;e_{2w}\,r_{1w} \,\overline{\overline{ \delta_{i+1/2} [T] }}^{\,i,k+1/2} 585 \right. \right. \\ 586 & \qquad \qquad \quad 587 - e_{1w}\,r_{2w} \,\overline{\overline{ \delta_{j+1/2} [T] }}^{\,j,k+1/2} \\ 588 & \left. {\left. { \qquad \qquad \ \ \ \left. { 589 +\;\frac{e_{1w}\,e_{2w}}{e_{3w}} \,\left( r_{1w}^2 + r_{2w}^2 \right) 590 \,\delta_{k+1/2} [T] } \right) } \right] \quad } \right\} 591 \end{split} 577 592 \end{equation} 578 593 where $b_t$=$e_{1t}\,e_{2t}\,e_{3t}$ is the volume of $T$-cells, … … 652 667 and is based on a laplacian operator. 653 668 The vertical diffusion operator given by (\autoref{eq:PE_zdf}) takes the following semi-discrete space form: 654 \ begin{equation} \label{eq:tra_zdf}655 \begin{split}656 D^{vT}_T &= \frac{1}{e_{3t}} \; \delta_k \left[ \;\frac{A^{vT}_w}{e_{3w}} \delta_{k+1/2}[T] \;\right] 657 \\658 D^{vS}_T &= \frac{1}{e_{3t}} \; \delta_k \left[ \;\frac{A^{vS}_w}{e_{3w}} \delta_{k+1/2}[S] \;\right] 659 \end{split}660 \ end{equation}669 \[ 670 % \label{eq:tra_zdf} 671 \begin{split} 672 D^{vT}_T &= \frac{1}{e_{3t}} \; \delta_k \left[ \;\frac{A^{vT}_w}{e_{3w}} \delta_{k+1/2}[T] \;\right] \\ 673 D^{vS}_T &= \frac{1}{e_{3t}} \; \delta_k \left[ \;\frac{A^{vS}_w}{e_{3w}} \delta_{k+1/2}[S] \;\right] 674 \end{split} 675 \] 661 676 where $A_w^{vT}$ and $A_w^{vS}$ are the vertical eddy diffusivity coefficients on temperature and salinity, 662 677 respectively. … … 726 741 727 742 The surface boundary condition on temperature and salinity is applied as follows: 728 \begin{equation} \label{eq:tra_sbc} 729 \begin{aligned} 730 &F^T = \frac{ 1 }{\rho_o \;C_p \,\left. e_{3t} \right|_{k=1} } &\overline{ Q_{ns} }^t & \\ 731 & F^S =\frac{ 1 }{\rho_o \, \left. e_{3t} \right|_{k=1} } &\overline{ \textit{sfx} }^t & \\ 732 \end{aligned} 743 \begin{equation} 744 \label{eq:tra_sbc} 745 \begin{aligned} 746 &F^T = \frac{ 1 }{\rho_o \;C_p \,\left. e_{3t} \right|_{k=1} } &\overline{ Q_{ns} }^t & \\ 747 & F^S =\frac{ 1 }{\rho_o \, \left. e_{3t} \right|_{k=1} } &\overline{ \textit{sfx} }^t & \\ 748 \end{aligned} 733 749 \end{equation} 734 750 where $\overline{x }^t$ means that $x$ is averaged over two consecutive time steps ($t-\rdt/2$ and $t+\rdt/2$). … … 741 757 the volume of the first level. 742 758 The resulting surface boundary condition is applied as follows: 743 \begin{equation} \label{eq:tra_sbc_lin} 744 \begin{aligned} 745 &F^T = \frac{ 1 }{\rho_o \;C_p \,\left. e_{3t} \right|_{k=1} } 746 &\overline{ \left( Q_{ns} - \textit{emp}\;C_p\,\left. T \right|_{k=1} \right) }^t & \\ 747 % 748 & F^S =\frac{ 1 }{\rho_o \,\left. e_{3t} \right|_{k=1} } 749 &\overline{ \left( \;\textit{sfx} - \textit{emp} \;\left. S \right|_{k=1} \right) }^t & \\ 750 \end{aligned} 759 \begin{equation} 760 \label{eq:tra_sbc_lin} 761 \begin{aligned} 762 &F^T = \frac{ 1 }{\rho_o \;C_p \,\left. e_{3t} \right|_{k=1} } 763 &\overline{ \left( Q_{ns} - \textit{emp}\;C_p\,\left. T \right|_{k=1} \right) }^t & \\ 764 % 765 & F^S =\frac{ 1 }{\rho_o \,\left. e_{3t} \right|_{k=1} } 766 &\overline{ \left( \;\textit{sfx} - \textit{emp} \;\left. S \right|_{k=1} \right) }^t & \\ 767 \end{aligned} 751 768 \end{equation} 752 769 Note that an exact conservation of heat and salt content is only achieved with non-linear free surface. … … 772 789 the surface boundary condition is modified to take into account only the non-penetrative part of the surface 773 790 heat flux: 774 \begin{equation} \label{eq:PE_qsr} 775 \begin{split} 776 \frac{\partial T}{\partial t} &= {\ldots} + \frac{1}{\rho_o\, C_p \,e_3} \; \frac{\partial I}{\partial k} \\ 777 Q_{ns} &= Q_\text{Total} - Q_{sr} 778 \end{split} 791 \begin{equation} 792 \label{eq:PE_qsr} 793 \begin{split} 794 \frac{\partial T}{\partial t} &= {\ldots} + \frac{1}{\rho_o\, C_p \,e_3} \; \frac{\partial I}{\partial k} \\ 795 Q_{ns} &= Q_\text{Total} - Q_{sr} 796 \end{split} 779 797 \end{equation} 780 798 where $Q_{sr}$ is the penetrative part of the surface heat flux ($i.e.$ the shortwave radiation) and 781 799 $I$ is the downward irradiance ($\left. I \right|_{z=\eta}=Q_{sr}$). 782 800 The additional term in \autoref{eq:PE_qsr} is discretized as follows: 783 \begin{equation} \label{eq:tra_qsr} 784 \frac{1}{\rho_o\, C_p \,e_3} \; \frac{\partial I}{\partial k} \equiv \frac{1}{\rho_o\, C_p\, e_{3t}} \delta_k \left[ I_w \right] 801 \begin{equation} 802 \label{eq:tra_qsr} 803 \frac{1}{\rho_o\, C_p \,e_3} \; \frac{\partial I}{\partial k} \equiv \frac{1}{\rho_o\, C_p\, e_{3t}} \delta_k \left[ I_w \right] 785 804 \end{equation} 786 805 … … 798 817 a chlorophyll-independent monochromatic formulation is chosen for the shorter wavelengths, 799 818 leading to the following expression \citep{Paulson1977}: 800 \begin{equation} \label{eq:traqsr_iradiance} 801 I(z) = Q_{sr} \left[Re^{-z / \xi_0} + \left( 1-R\right) e^{-z / \xi_1} \right] 802 \end{equation} 819 \[ 820 % \label{eq:traqsr_iradiance} 821 I(z) = Q_{sr} \left[Re^{-z / \xi_0} + \left( 1-R\right) e^{-z / \xi_1} \right] 822 \] 803 823 where $\xi_1$ is the second extinction length scale associated with the shorter wavelengths. 804 824 It is usually chosen to be 23~m by setting the \np{rn\_si0} namelist parameter. … … 857 877 \begin{center} 858 878 \includegraphics[width=1.0\textwidth]{Fig_TRA_Irradiance} 859 \caption{ \protect\label{fig:traqsr_irradiance} 879 \caption{ 880 \protect\label{fig:traqsr_irradiance} 860 881 Penetration profile of the downward solar irradiance calculated by four models. 861 882 Two waveband chlorophyll-independent formulation (blue), … … 883 904 \begin{center} 884 905 \includegraphics[width=1.0\textwidth]{Fig_TRA_geoth} 885 \caption{ \protect\label{fig:geothermal} 906 \caption{ 907 \protect\label{fig:geothermal} 886 908 Geothermal Heat flux (in $mW.m^{-2}$) used by \cite{Emile-Geay_Madec_OS09}. 887 909 It is inferred from the age of the sea floor and the formulae of \citet{Stein_Stein_Nat92}. … … 947 969 When applying sigma-diffusion (\key{trabbl} defined and \np{nn\_bbl\_ldf} set to 1), 948 970 the diffusive flux between two adjacent cells at the ocean floor is given by 949 \begin{equation} \label{eq:tra_bbl_diff} 950 {\rm {\bf F}}_\sigma=A_l^\sigma \; \nabla_\sigma T 951 \end{equation} 971 \[ 972 % \label{eq:tra_bbl_diff} 973 {\rm {\bf F}}_\sigma=A_l^\sigma \; \nabla_\sigma T 974 \] 952 975 with $\nabla_\sigma$ the lateral gradient operator taken between bottom cells, 953 976 and $A_l^\sigma$ the lateral diffusivity in the BBL. 954 977 Following \citet{Beckmann_Doscher1997}, the latter is prescribed with a spatial dependence, 955 978 $i.e.$ in the conditional form 956 \begin{equation} \label{eq:tra_bbl_coef} 957 A_l^\sigma (i,j,t)=\left\{ {\begin{array}{l} 958 A_{bbl} \quad \quad \mbox{if} \quad \nabla_\sigma \rho \cdot \nabla H<0 \\ 959 \\ 960 0\quad \quad \;\,\mbox{otherwise} \\ 961 \end{array}} \right. 979 \begin{equation} 980 \label{eq:tra_bbl_coef} 981 A_l^\sigma (i,j,t)=\left\{ { 982 \begin{array}{l} 983 A_{bbl} \quad \quad \mbox{if} \quad \nabla_\sigma \rho \cdot \nabla H<0 \\ \\ 984 0\quad \quad \;\,\mbox{otherwise} \\ 985 \end{array}} 986 \right. 962 987 \end{equation} 963 988 where $A_{bbl}$ is the BBL diffusivity coefficient, given by the namelist parameter \np{rn\_ahtbbl} and … … 968 993 In practice, this constraint is applied separately in the two horizontal directions, 969 994 and the density gradient in \autoref{eq:tra_bbl_coef} is evaluated with the log gradient formulation: 970 \begin{equation} \label{eq:tra_bbl_Drho} 971 \nabla_\sigma \rho / \rho = \alpha \,\nabla_\sigma T + \beta \,\nabla_\sigma S 972 \end{equation} 995 \[ 996 % \label{eq:tra_bbl_Drho} 997 \nabla_\sigma \rho / \rho = \alpha \,\nabla_\sigma T + \beta \,\nabla_\sigma S 998 \] 973 999 where $\rho$, $\alpha$ and $\beta$ are functions of $\overline{T}^\sigma$, 974 1000 $\overline{S}^\sigma$ and $\overline{H}^\sigma$, the along bottom mean temperature, salinity and depth, respectively. … … 987 1013 \begin{center} 988 1014 \includegraphics[width=0.7\textwidth]{Fig_BBL_adv} 989 \caption{ \protect\label{fig:bbl} 1015 \caption{ 1016 \protect\label{fig:bbl} 990 1017 Advective/diffusive Bottom Boundary Layer. 991 1018 The BBL parameterisation is activated when $\rho^i_{kup}$ is larger than $\rho^{i+1}_{kdnw}$. … … 1024 1051 For example, the resulting transport of the downslope flow, here in the $i$-direction (\autoref{fig:bbl}), 1025 1052 is simply given by the following expression: 1026 \begin{equation} \label{eq:bbl_Utr} 1027 u^{tr}_{bbl} = \gamma \, g \frac{\Delta \rho}{\rho_o} e_{1u} \; min \left( {e_{3u}}_{kup},{e_{3u}}_{kdwn} \right) 1028 \end{equation} 1053 \[ 1054 % \label{eq:bbl_Utr} 1055 u^{tr}_{bbl} = \gamma \, g \frac{\Delta \rho}{\rho_o} e_{1u} \; min \left( {e_{3u}}_{kup},{e_{3u}}_{kdwn} \right) 1056 \] 1029 1057 where $\gamma$, expressed in seconds, is the coefficient of proportionality provided as \np{rn\_gambbl}, 1030 1058 a namelist parameter, and \textit{kup} and \textit{kdwn} are the vertical index of the higher and lower cells, … … 1043 1071 the downslope flow \autoref{eq:bbl_dw}, the horizontal \autoref{eq:bbl_hor} and 1044 1072 the upward \autoref{eq:bbl_up} return flows as follows: 1045 \begin{align} 1046 \partial_t T^{do}_{kdw} &\equiv \partial_t T^{do}_{kdw}1047 1048 %1049 \partial_t T^{sh}_{kup} &\equiv \partial_t T^{sh}_{kup} 1050 1051 %1052 \intertext{and for $k =kdw-1,\;..., \; kup$ :} 1053 %1054 \partial_t T^{do}_{k} &\equiv \partial_t S^{do}_{k}1055 1073 \begin{align} 1074 \partial_t T^{do}_{kdw} &\equiv \partial_t T^{do}_{kdw} 1075 + \frac{u^{tr}_{bbl}}{{b_t}^{do}_{kdw}} \left( T^{sh}_{kup} - T^{do}_{kdw} \right) \label{eq:bbl_dw} \\ 1076 % 1077 \partial_t T^{sh}_{kup} &\equiv \partial_t T^{sh}_{kup} 1078 + \frac{u^{tr}_{bbl}}{{b_t}^{sh}_{kup}} \left( T^{do}_{kup} - T^{sh}_{kup} \right) \label{eq:bbl_hor} \\ 1079 % 1080 \intertext{and for $k =kdw-1,\;..., \; kup$ :} 1081 % 1082 \partial_t T^{do}_{k} &\equiv \partial_t S^{do}_{k} 1083 + \frac{u^{tr}_{bbl}}{{b_t}^{do}_{k}} \left( T^{do}_{k+1} - T^{sh}_{k} \right) \label{eq:bbl_up} 1056 1084 \end{align} 1057 1085 where $b_t$ is the $T$-cell volume. … … 1071 1099 1072 1100 In some applications it can be useful to add a Newtonian damping term into the temperature and salinity equations: 1073 \begin{equation} \label{eq:tra_dmp} 1074 \begin{split} 1075 \frac{\partial T}{\partial t}=\;\cdots \;-\gamma \,\left( {T-T_o } \right) \\ 1076 \frac{\partial S}{\partial t}=\;\cdots \;-\gamma \,\left( {S-S_o } \right) 1077 \end{split} 1101 \begin{equation} 1102 \label{eq:tra_dmp} 1103 \begin{split} 1104 \frac{\partial T}{\partial t}=\;\cdots \;-\gamma \,\left( {T-T_o } \right) \\ 1105 \frac{\partial S}{\partial t}=\;\cdots \;-\gamma \,\left( {S-S_o } \right) 1106 \end{split} 1078 1107 \end{equation} 1079 1108 where $\gamma$ is the inverse of a time scale, and $T_o$ and $S_o$ are given temperature and salinity fields … … 1173 1202 The general framework for tracer time stepping is a modified leap-frog scheme \citep{Leclair_Madec_OM09}, 1174 1203 $i.e.$ a three level centred time scheme associated with a Asselin time filter (cf. \autoref{sec:STP_mLF}): 1175 \begin{equation} \label{eq:tra_nxt}1176 \begin{aligned}1177 (e_{3t}T)^{t+\rdt} &= (e_{3t}T)_f^{t-\rdt} &+ 2 \, \rdt \,e_{3t}^t\ \text{RHS}^t & \\ 1178 \\1179 (e_{3t}T)_f^t \;\ \quad &= (e_{3t}T)^t \;\quad 1180 1181 & &- \gamma\,\rdt \, \left[ Q^{t+\rdt/2} - Q^{t-\rdt/2} \right] &1182 \end{aligned}1204 \begin{equation} 1205 \label{eq:tra_nxt} 1206 \begin{aligned} 1207 (e_{3t}T)^{t+\rdt} &= (e_{3t}T)_f^{t-\rdt} &+ 2 \, \rdt \,e_{3t}^t\ \text{RHS}^t & \\ \\ 1208 (e_{3t}T)_f^t \;\ \quad &= (e_{3t}T)^t \;\quad 1209 &+\gamma \,\left[ {(e_{3t}T)_f^{t-\rdt} -2(e_{3t}T)^t+(e_{3t}T)^{t+\rdt}} \right] & \\ 1210 & &- \gamma\,\rdt \, \left[ Q^{t+\rdt/2} - Q^{t-\rdt/2} \right] & 1211 \end{aligned} 1183 1212 \end{equation} 1184 1213 where RHS is the right hand side of the temperature equation, the subscript $f$ denotes filtered values, … … 1288 1317 as well as between \textit{absolute} and \textit{practical} salinity. 1289 1318 S-EOS takes the following expression: 1290 \begin{equation} \label{eq:tra_S-EOS} 1319 \[ 1320 % \label{eq:tra_S-EOS} 1291 1321 \begin{split} 1292 1322 d_a(T,S,z) = ( & - a_0 \; ( 1 + 0.5 \; \lambda_1 \; T_a + \mu_1 \; z ) * T_a \\ … … 1295 1325 with \ \ T_a = T-10 \; ; & \; S_a = S-35 \; ;\; \rho_o = 1026~Kg/m^3 1296 1326 \end{split} 1297 \ end{equation}1327 \] 1298 1328 where the computer name of the coefficients as well as their standard value are given in \autoref{tab:SEOS}. 1299 1329 In fact, when choosing S-EOS, various approximation of EOS can be specified simply by changing the associated coefficients. … … 1306 1336 %>>>>>>>>>>>>>>>>>>>>>>>>>>>> 1307 1337 \begin{table}[!tb] 1308 \begin{center} \begin{tabular}{|p{26pt}|p{72pt}|p{56pt}|p{136pt}|} 1309 \hline 1310 coeff. & computer name & S-EOS & description \\ \hline 1311 $a_0$ & \np{rn\_a0} & 1.6550 $10^{-1}$ & linear thermal expansion coeff. \\ \hline 1312 $b_0$ & \np{rn\_b0} & 7.6554 $10^{-1}$ & linear haline expansion coeff. \\ \hline 1313 $\lambda_1$ & \np{rn\_lambda1}& 5.9520 $10^{-2}$ & cabbeling coeff. in $T^2$ \\ \hline 1314 $\lambda_2$ & \np{rn\_lambda2}& 5.4914 $10^{-4}$ & cabbeling coeff. in $S^2$ \\ \hline 1315 $\nu$ & \np{rn\_nu} & 2.4341 $10^{-3}$ & cabbeling coeff. in $T \, S$ \\ \hline 1316 $\mu_1$ & \np{rn\_mu1} & 1.4970 $10^{-4}$ & thermobaric coeff. in T \\ \hline 1317 $\mu_2$ & \np{rn\_mu2} & 1.1090 $10^{-5}$ & thermobaric coeff. in S \\ \hline 1318 \end{tabular} 1319 \caption{ \protect\label{tab:SEOS} 1320 Standard value of S-EOS coefficients. 1321 } 1322 \end{center} 1338 \begin{center} 1339 \begin{tabular}{|p{26pt}|p{72pt}|p{56pt}|p{136pt}|} 1340 \hline 1341 coeff. & computer name & S-EOS & description \\ \hline 1342 $a_0$ & \np{rn\_a0} & 1.6550 $10^{-1}$ & linear thermal expansion coeff. \\ \hline 1343 $b_0$ & \np{rn\_b0} & 7.6554 $10^{-1}$ & linear haline expansion coeff. \\ \hline 1344 $\lambda_1$ & \np{rn\_lambda1}& 5.9520 $10^{-2}$ & cabbeling coeff. in $T^2$ \\ \hline 1345 $\lambda_2$ & \np{rn\_lambda2}& 5.4914 $10^{-4}$ & cabbeling coeff. in $S^2$ \\ \hline 1346 $\nu$ & \np{rn\_nu} & 2.4341 $10^{-3}$ & cabbeling coeff. in $T \, S$ \\ \hline 1347 $\mu_1$ & \np{rn\_mu1} & 1.4970 $10^{-4}$ & thermobaric coeff. in T \\ \hline 1348 $\mu_2$ & \np{rn\_mu2} & 1.1090 $10^{-5}$ & thermobaric coeff. in S \\ \hline 1349 \end{tabular} 1350 \caption{ 1351 \protect\label{tab:SEOS} 1352 Standard value of S-EOS coefficients. 1353 } 1354 \end{center} 1323 1355 \end{table} 1324 1356 %>>>>>>>>>>>>>>>>>>>>>>>>>>>> … … 1338 1370 (pressure in decibar being approximated by the depth in meters). 1339 1371 The expression for $N^2$ is given by: 1340 \begin{equation} \label{eq:tra_bn2} 1341 N^2 = \frac{g}{e_{3w}} \left( \beta \;\delta_{k+1/2}[S] - \alpha \;\delta_{k+1/2}[T] \right) 1342 \end{equation} 1372 \[ 1373 % \label{eq:tra_bn2} 1374 N^2 = \frac{g}{e_{3w}} \left( \beta \;\delta_{k+1/2}[S] - \alpha \;\delta_{k+1/2}[T] \right) 1375 \] 1343 1376 where $(T,S) = (\Theta, S_A)$ for TEOS10, $= (\theta, S_p)$ for TEOS-80, or $=(T,S)$ for S-EOS, 1344 1377 and, $\alpha$ and $\beta$ are the thermal and haline expansion coefficients. … … 1354 1387 1355 1388 The freezing point of seawater is a function of salinity and pressure \citep{UNESCO1983}: 1356 \begin{equation} \label{eq:tra_eos_fzp}1357 \begin{split}1358 T_f (S,p) = \left( -0.0575 + 1.710523 \;10^{-3} \, \sqrt{S} 1359 1360 - 7.53\,10^{-3} \ \ p1361 1389 \begin{equation} 1390 \label{eq:tra_eos_fzp} 1391 \begin{split} 1392 T_f (S,p) = \left( -0.0575 + 1.710523 \;10^{-3} \, \sqrt{S} - 2.154996 \;10^{-4} \,S \right) \ S \\ 1393 - 7.53\,10^{-3} \ \ p 1394 \end{split} 1362 1395 \end{equation} 1363 1396 … … 1405 1438 \begin{center} 1406 1439 \includegraphics[width=0.9\textwidth]{Fig_partial_step_scheme} 1407 \caption{ \protect\label{fig:Partial_step_scheme} 1440 \caption{ 1441 \protect\label{fig:Partial_step_scheme} 1408 1442 Discretisation of the horizontal difference and average of tracers in the $z$-partial step coordinate 1409 1443 (\protect\np{ln\_zps}\forcode{ = .true.}) in the case $( e3w_k^{i+1} - e3w_k^i )>0$. … … 1417 1451 %>>>>>>>>>>>>>>>>>>>>>>>>>>>> 1418 1452 \[ 1419 \widetilde{T}= \left\{ \begin{aligned} 1420 &T^{\,i+1} -\frac{ \left( e_{3w}^{i+1} -e_{3w}^i \right)}{ e_{3w}^{i+1} }\;\delta_k T^{i+1} 1421 && \quad\text{if $\ e_{3w}^{i+1} \geq e_{3w}^i$ } \\ 1422 \\ 1423 &T^{\,i} \ \ \ \,+\frac{ \left( e_{3w}^{i+1} -e_{3w}^i \right) }{e_{3w}^i }\;\delta_k T^{i+1} 1424 && \quad\text{if $\ e_{3w}^{i+1} < e_{3w}^i$ } 1425 \end{aligned} \right. 1453 \widetilde{T}= \left\{ 1454 \begin{aligned} 1455 &T^{\,i+1} -\frac{ \left( e_{3w}^{i+1} -e_{3w}^i \right)}{ e_{3w}^{i+1} }\;\delta_k T^{i+1} 1456 && \quad\text{if $\ e_{3w}^{i+1} \geq e_{3w}^i$ } \\ \\ 1457 &T^{\,i} \ \ \ \,+\frac{ \left( e_{3w}^{i+1} -e_{3w}^i \right) }{e_{3w}^i }\;\delta_k T^{i+1} 1458 && \quad\text{if $\ e_{3w}^{i+1} < e_{3w}^i$ } 1459 \end{aligned} 1460 \right. 1426 1461 \] 1427 1462 and the resulting forms for the horizontal difference and the horizontal average value of $T$ at a $U$-point are: 1428 \begin{equation} \label{eq:zps_hde} 1429 \begin{aligned} 1430 \delta_{i+1/2} T= \begin{cases} 1431 \ \ \ \widetilde {T}\quad\ -T^i & \ \ \quad\quad\text{if $\ e_{3w}^{i+1} \geq e_{3w}^i$ } \\ 1432 \\ 1433 \ \ \ T^{\,i+1}-\widetilde{T} & \ \ \quad\quad\text{if $\ e_{3w}^{i+1} < e_{3w}^i$ } 1434 \end{cases} \\ 1435 \\ 1436 \overline {T}^{\,i+1/2} \ = \begin{cases} 1437 ( \widetilde {T}\ \ \;\,-T^{\,i}) / 2 & \;\ \ \quad\text{if $\ e_{3w}^{i+1} \geq e_{3w}^i$ } \\ 1438 \\ 1439 ( T^{\,i+1}-\widetilde{T} ) / 2 & \;\ \ \quad\text{if $\ e_{3w}^{i+1} < e_{3w}^i$ } 1440 \end{cases} 1441 \end{aligned} 1463 \begin{equation} 1464 \label{eq:zps_hde} 1465 \begin{aligned} 1466 \delta_{i+1/2} T= 1467 \begin{cases} 1468 \ \ \ \widetilde {T}\quad\ -T^i & \ \ \quad\quad\text{if $\ e_{3w}^{i+1} \geq e_{3w}^i$ } \\ \\ 1469 \ \ \ T^{\,i+1}-\widetilde{T} & \ \ \quad\quad\text{if $\ e_{3w}^{i+1} < e_{3w}^i$ } 1470 \end{cases} 1471 \\ \\ 1472 \overline {T}^{\,i+1/2} \ = 1473 \begin{cases} 1474 ( \widetilde {T}\ \ \;\,-T^{\,i}) / 2 & \;\ \ \quad\text{if $\ e_{3w}^{i+1} \geq e_{3w}^i$ } \\ \\ 1475 ( T^{\,i+1}-\widetilde{T} ) / 2 & \;\ \ \quad\text{if $\ e_{3w}^{i+1} < e_{3w}^i$ } 1476 \end{cases} 1477 \end{aligned} 1442 1478 \end{equation} 1443 1479 … … 1449 1485 $T$ and $S$, and the pressure at a $u$-point 1450 1486 (in the equation of state pressure is approximated by depth, see \autoref{subsec:TRA_eos} ): 1451 \begin{equation} \label{eq:zps_hde_rho} 1452 \widetilde{\rho } = \rho ( {\widetilde{T},\widetilde {S},z_u }) 1453 \quad \text{where }\ z_u = \min \left( {z_T^{i+1} ,z_T^i } \right) 1454 \end{equation} 1487 \[ 1488 % \label{eq:zps_hde_rho} 1489 \widetilde{\rho } = \rho ( {\widetilde{T},\widetilde {S},z_u }) 1490 \quad \text{where }\ z_u = \min \left( {z_T^{i+1} ,z_T^i } \right) 1491 \] 1455 1492 1456 1493 This is a much better approximation as the variation of $\rho$ with depth (and thus pressure) … … 1471 1508 \gmcomment{gm : this last remark has to be done} 1472 1509 %%% 1510 1511 \biblio 1512 1473 1513 \end{document}
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