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Changeset 6440 for branches/UKMO/dev_r5518_GC3p0_package/DOC/TexFiles/Chapters/Chap_SBC.tex – NEMO

Ignore:
Timestamp:
2016-04-07T16:32:24+02:00 (8 years ago)
Author:
dancopsey
Message:

Merged in nemo_v3_6_STABLE_copy up to revision 6436.

File:
1 edited

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  • branches/UKMO/dev_r5518_GC3p0_package/DOC/TexFiles/Chapters/Chap_SBC.tex

    r5120 r6440  
    11% ================================================================ 
    2 % Chapter � Surface Boundary Condition (SBC, ISF, ICB)  
     2% Chapter —— Surface Boundary Condition (SBC, ISF, ICB)  
    33% ================================================================ 
    44\chapter{Surface Boundary Condition (SBC, ISF, ICB) } 
    … …  
    1717   \item the two components of the surface ocean stress $\left( {\tau _u \;,\;\tau _v} \right)$ 
    1818   \item the incoming solar and non solar heat fluxes $\left( {Q_{ns} \;,\;Q_{sr} } \right)$ 
    19    \item the surface freshwater budget $\left( {\textit{emp},\;\textit{emp}_S } \right)$ 
     19   \item the surface freshwater budget $\left( {\textit{emp}} \right)$ 
     20   \item the surface salt flux associated with freezing/melting of seawater $\left( {\textit{sfx}} \right)$ 
    2021\end{itemize} 
    2122plus an optional field: 
    … …  
    2728are controlled by namelist \ngn{namsbc} variables: an analytical formulation (\np{ln\_ana}~=~true),  
    2829a flux formulation (\np{ln\_flx}~=~true), a bulk formulae formulation (CORE  
    29 (\np{ln\_core}~=~true), CLIO (\np{ln\_clio}~=~true) or MFS 
     30(\np{ln\_blk\_core}~=~true), CLIO (\np{ln\_blk\_clio}~=~true) or MFS 
    3031\footnote { Note that MFS bulk formulae compute fluxes only for the ocean component} 
    31 (\np{ln\_mfs}~=~true) bulk formulae) and a coupled  
    32 formulation (exchanges with a atmospheric model via the OASIS coupler)  
    33 (\np{ln\_cpl}~=~true). When used, the atmospheric pressure forces both  
    34 ocean and ice dynamics (\np{ln\_apr\_dyn}~=~true). 
    35 The frequency at which the six or seven fields have to be updated is the \np{nn\_fsbc}  
    36 namelist parameter.  
     32(\np{ln\_blk\_mfs}~=~true) bulk formulae) and a coupled or mixed forced/coupled formulation  
     33(exchanges with a atmospheric model via the OASIS coupler) (\np{ln\_cpl} or \np{ln\_mixcpl}~=~true).  
     34When used ($i.e.$ \np{ln\_apr\_dyn}~=~true), the atmospheric pressure forces both ocean and ice dynamics. 
     35 
     36The frequency at which the forcing fields have to be updated is given by the \np{nn\_fsbc} namelist parameter.  
    3737When the fields are supplied from data files (flux and bulk formulations), the input fields  
    38 need not be supplied on the model grid.  Instead a file of coordinates and weights can  
     38need not be supplied on the model grid. Instead a file of coordinates and weights can  
    3939be supplied which maps the data from the supplied grid to the model points  
    4040(so called "Interpolation on the Fly", see \S\ref{SBC_iof}). 
    … …  
    4242can be masked to avoid spurious results in proximity of the coasts  as large sea-land gradients characterize 
    4343most of the atmospheric variables. 
     44 
    4445In addition, the resulting fields can be further modified using several namelist options.  
    45 These options control  the rotation of vector components supplied relative to an east-north  
    46 coordinate system onto the local grid directions in the model; the addition of a surface  
    47 restoring term to observed SST and/or SSS (\np{ln\_ssr}~=~true); the modification of fluxes  
    48 below ice-covered areas (using observed ice-cover or a sea-ice model)  
    49 (\np{nn\_ice}~=~0,1, 2 or 3); the addition of river runoffs as surface freshwater  
    50 fluxes or lateral inflow (\np{ln\_rnf}~=~true); the addition of isf melting as lateral inflow (parameterisation)  
    51 (\np{nn\_isf}~=~2 or 3 and \np{ln\_isfcav}~=~false) or as surface flux at the land-ice ocean interface 
    52 (\np{nn\_isf}~=~1 or 4 and \np{ln\_isfcav}~=~true);  
    53 the addition of a freshwater flux adjustment in order to avoid a mean sea-level drift (\np{nn\_fwb}~=~0,~1~or~2); the  
    54 transformation of the solar radiation (if provided as daily mean) into a diurnal  
    55 cycle (\np{ln\_dm2dc}~=~true); and a neutral drag coefficient can be read from an external wave  
    56 model (\np{ln\_cdgw}~=~true). The latter option is possible only in case core or mfs bulk formulas are selected. 
     46These options control  
     47\begin{itemize} 
     48\item the rotation of vector components supplied relative to an east-north  
     49coordinate system onto the local grid directions in the model ;  
     50\item the addition of a surface restoring term to observed SST and/or SSS (\np{ln\_ssr}~=~true) ;  
     51\item the modification of fluxes below ice-covered areas (using observed ice-cover or a sea-ice model) (\np{nn\_ice}~=~0,1, 2 or 3) ;  
     52\item the addition of river runoffs as surface freshwater fluxes or lateral inflow (\np{ln\_rnf}~=~true) ;  
     53\item the addition of isf melting as lateral inflow (parameterisation) (\np{nn\_isf}~=~2 or 3 and \np{ln\_isfcav}~=~false)  
     54or as fluxes applied at the land-ice ocean interface (\np{nn\_isf}~=~1 or 4 and \np{ln\_isfcav}~=~true) ;  
     55\item the addition of a freshwater flux adjustment in order to avoid a mean sea-level drift (\np{nn\_fwb}~=~0,~1~or~2) ;  
     56\item the transformation of the solar radiation (if provided as daily mean) into a diurnal cycle (\np{ln\_dm2dc}~=~true) ;  
     57and a neutral drag coefficient can be read from an external wave model (\np{ln\_cdgw}~=~true).  
     58\end{itemize} 
     59The latter option is possible only in case core or mfs bulk formulas are selected. 
    5760 
    5861In this chapter, we first discuss where the surface boundary condition appears in the 
    … …  
    7376 
    7477The surface ocean stress is the stress exerted by the wind and the sea-ice  
    75 on the ocean. The two components of stress are assumed to be interpolated  
    76 onto the ocean mesh, $i.e.$ resolved onto the model (\textbf{i},\textbf{j}) direction  
    77 at $u$- and $v$-points They are applied as a surface boundary condition of the  
    78 computation of the momentum vertical mixing trend (\mdl{dynzdf} module) : 
    79 \begin{equation} \label{Eq_sbc_dynzdf} 
    80 \left.{\left( {\frac{A^{vm} }{e_3 }\ \frac{\partial \textbf{U}_h}{\partial k}} \right)} \right|_{z=1} 
    81     = \frac{1}{\rho _o} \binom{\tau _u}{\tau _v } 
    82 \end{equation} 
    83 where $(\tau _u ,\;\tau _v )=(utau,vtau)$ are the two components of the wind  
    84 stress vector in the $(\textbf{i},\textbf{j})$ coordinate system. 
     78on the ocean. It is applied in \mdl{dynzdf} module as a surface boundary condition of the  
     79computation of the momentum vertical mixing trend (see \eqref{Eq_dynzdf_sbc} in \S\ref{DYN_zdf}). 
     80As such, it has to be provided as a 2D vector interpolated  
     81onto the horizontal velocity ocean mesh, $i.e.$ resolved onto the model  
     82(\textbf{i},\textbf{j}) direction at $u$- and $v$-points. 
    8583 
    8684The surface heat flux is decomposed into two parts, a non solar and a solar heat  
    8785flux, $Q_{ns}$ and $Q_{sr}$, respectively. The former is the non penetrative part  
    88 of the heat flux ($i.e.$ the sum of sensible, latent and long wave heat fluxes).  
    89 It is applied as a surface boundary condition trend of the first level temperature  
    90 time evolution equation (\mdl{trasbc} module).  
    91 \begin{equation} \label{Eq_sbc_trasbc_q} 
    92 \frac{\partial T}{\partial t}\equiv \cdots \;+\;\left. {\frac{Q_{ns} }{\rho  
    93 _o \;C_p \;e_{3t} }} \right|_{k=1} \quad 
    94 \end{equation} 
    95 $Q_{sr}$ is the penetrative part of the heat flux. It is applied as a 3D  
    96 trends of the temperature equation (\mdl{traqsr} module) when \np{ln\_traqsr}=True. 
    97  
    98 \begin{equation} \label{Eq_sbc_traqsr} 
    99 \frac{\partial T}{\partial t}\equiv \cdots \;+\frac{Q_{sr} }{\rho_o C_p \,e_{3t} }\delta _k \left[ {I_w } \right] 
    100 \end{equation} 
    101 where $I_w$ is a non-dimensional function that describes the way the light  
    102 penetrates inside the water column. It is generally a sum of decreasing  
    103 exponentials (see \S\ref{TRA_qsr}). 
    104  
    105 The surface freshwater budget is provided by fields: \textit{emp} and $\textit{emp}_S$ which  
    106 may or may not be identical. Indeed, a surface freshwater flux has two effects:  
    107 it changes the volume of the ocean and it changes the surface concentration of  
    108 salt (and other tracers). Therefore it appears in the sea surface height as a volume  
    109 flux, \textit{emp} (\textit{dynspg\_xxx} modules), and in the salinity time evolution equations  
    110 as a concentration/dilution effect,  
    111 $\textit{emp}_{S}$ (\mdl{trasbc} module).  
    112 \begin{equation} \label{Eq_trasbc_emp} 
    113 \begin{aligned} 
    114 &\frac{\partial \eta }{\partial t}\equiv \cdots \;+\;\textit{emp}\quad  \\  
    115 \\ 
    116  &\frac{\partial S}{\partial t}\equiv \cdots \;+\left. {\frac{\textit{emp}_S \;S}{e_{3t} }} \right|_{k=1} \\  
    117  \end{aligned} 
    118 \end{equation}  
    119  
    120 In the real ocean, $\textit{emp}=\textit{emp}_S$ and the ocean salt content is conserved,  
    121 but it exist several numerical reasons why this equality should be broken.  
    122 For example, when the ocean is coupled to a sea-ice model, the water exchanged between  
    123 ice and ocean is slightly salty (mean sea-ice salinity is $\sim $\textit{4 psu}). In this case,  
    124 $\textit{emp}_{S}$ take into account both concentration/dilution effect associated with  
    125 freezing/melting and the salt flux between ice and ocean, while \textit{emp} is  
    126 only the volume flux. In addition, in the current version of \NEMO, the sea-ice is  
    127 assumed to be above the ocean (the so-called levitating sea-ice). Freezing/melting does  
    128 not change the ocean volume (no impact on \textit{emp}) but it modifies the SSS. 
    129 %gm  \colorbox{yellow}{(see {\S} on LIM sea-ice model)}. 
    130  
    131 Note that SST can also be modified by a freshwater flux. Precipitation (in  
    132 particular solid precipitation) may have a temperature significantly different from  
    133 the SST. Due to the lack of information about the temperature of  
    134 precipitation, we assume it is equal to the SST. Therefore, no  
    135 concentration/dilution term appears in the temperature equation. It has to  
    136 be emphasised that this absence does not mean that there is no heat flux  
    137 associated with precipitation! Precipitation can change the ocean volume and thus the 
    138 ocean heat content. It is therefore associated with a heat flux (not yet   
    139 diagnosed in the model) \citep{Roullet_Madec_JGR00}). 
     86of the heat flux ($i.e.$ the sum of sensible, latent and long wave heat fluxes  
     87plus the heat content of the mass exchange with the atmosphere and sea-ice).  
     88It is applied in \mdl{trasbc} module as a surface boundary condition trend of  
     89the first level temperature time evolution equation (see \eqref{Eq_tra_sbc}  
     90and \eqref{Eq_tra_sbc_lin} in \S\ref{TRA_sbc}).  
     91The latter is the penetrative part of the heat flux. It is applied as a 3D  
     92trends of the temperature equation (\mdl{traqsr} module) when \np{ln\_traqsr}=\textit{true}. 
     93The way the light penetrates inside the water column is generally a sum of decreasing  
     94exponentials (see \S\ref{TRA_qsr}).  
     95 
     96The surface freshwater budget is provided by the \textit{emp} field. 
     97It represents the mass flux exchanged with the atmosphere (evaporation minus precipitation)  
     98and possibly with the sea-ice and ice shelves (freezing minus melting of ice).  
     99It affects both the ocean in two different ways:  
     100$(i)$   it changes the volume of the ocean and therefore appears in the sea surface height  
     101equation as a volume flux, and  
     102$(ii)$  it changes the surface temperature and salinity through the heat and salt contents  
     103of the mass exchanged with the atmosphere, the sea-ice and the ice shelves.  
     104 
    140105 
    141106%\colorbox{yellow}{Miss: } 
    … …  
    152117%Sbcmod manage the ``providing'' (fourniture) to the ocean the 7 fields 
    153118% 
    154 %Fluxes update only each nf{\_}sbc time step (namsbc) explain relation  
    155 %between nf{\_}sbc and nf{\_}ice, do we define nf{\_}blk??? ? only one  
    156 %nf{\_}sbc 
     119%Fluxes update only each nn{\_}fsbc time step (namsbc) explain relation  
     120%between nn{\_}fsbc and nf{\_}ice, do we define nf{\_}blk??? ? only one  
     121%nn{\_}fsbc 
    157122% 
    158123%Explain here all the namlist namsbc variable{\ldots}. 
     124%  
     125% explain : use or not of surface currents 
    159126% 
    160127%\colorbox{yellow}{End Miss } 
    161128 
    162 The ocean model provides the surface currents, temperature and salinity  
    163 averaged over \np{nf\_sbc} time-step (\ref{Tab_ssm}).The computation of the  
    164 mean is done in \mdl{sbcmod} module. 
     129The ocean model provides, at each time step, to the surface module (\mdl{sbcmod})  
     130the surface currents, temperature and salinity.   
     131These variables are averaged over \np{nn\_fsbc} time-step (\ref{Tab_ssm}),  
     132and it is these averaged fields which are used to computes the surface fluxes  
     133at a frequency of \np{nn\_fsbc} time-step. 
     134 
    165135 
    166136%-------------------------------------------------TABLE--------------------------------------------------- 
    … …  
    175145\caption{  \label{Tab_ssm}    
    176146Ocean variables provided by the ocean to the surface module (SBC).  
    177 The variable are averaged over nf{\_}sbc time step, $i.e.$ the frequency of  
     147The variable are averaged over nn{\_}fsbc time step, $i.e.$ the frequency of  
    178148computation of surface fluxes.} 
    179149\end{center}   \end{table} 
    … …  
    459429%-------------------------------------------------------------------------------------------------------------- 
    460430 
    461 In some circumstances it may be useful to avoid calculating the 3D temperature, salinity and velocity fields and simply read them in from  a previous run.   
    462 Options are defined through the  \ngn{namsbc\_sas} namelist variables. 
     431In some circumstances it may be useful to avoid calculating the 3D temperature, salinity and velocity fields  
     432and simply read them in from a previous run or receive them from OASIS.   
    463433For example: 
    464434 
    465 \begin{enumerate} 
    466 \item  Multiple runs of the model are required in code development to see the affect of different algorithms in 
     435\begin{itemize} 
     436\item  Multiple runs of the model are required in code development to see the effect of different algorithms in 
    467437       the bulk formulae. 
    468438\item  The effect of different parameter sets in the ice model is to be examined. 
    469 \end{enumerate} 
     439\item  Development of sea-ice algorithms or parameterizations. 
     440\item  spinup of the iceberg floats 
     441\item  ocean/sea-ice simulation with both media running in parallel (\np{ln\_mixcpl}~=~\textit{true}) 
     442\end{itemize} 
    470443 
    471444The StandAlone Surface scheme provides this utility. 
     445Its options are defined through the \ngn{namsbc\_sas} namelist variables. 
    472446A new copy of the model has to be compiled with a configuration based on ORCA2\_SAS\_LIM. 
    473447However no namelist parameters need be changed from the settings of the previous run (except perhaps nn{\_}date0) 
    … …  
    475449Routines replaced are: 
    476450 
    477 \begin{enumerate} 
    478 \item  \mdl{nemogcm} 
    479  
    480        This routine initialises the rest of the model and repeatedly calls the stp time stepping routine (step.F90) 
     451\begin{itemize} 
     452\item \mdl{nemogcm} : This routine initialises the rest of the model and repeatedly calls the stp time stepping routine (step.F90) 
    481453       Since the ocean state is not calculated all associated initialisations have been removed. 
    482 \item  \mdl{step} 
    483  
    484        The main time stepping routine now only needs to call the sbc routine (and a few utility functions). 
    485 \item  \mdl{sbcmod} 
    486  
    487        This has been cut down and now only calculates surface forcing and the ice model required.  New surface modules 
     454\item  \mdl{step} : The main time stepping routine now only needs to call the sbc routine (and a few utility functions). 
     455\item  \mdl{sbcmod} : This has been cut down and now only calculates surface forcing and the ice model required.  New surface modules 
    488456       that can function when only the surface level of the ocean state is defined can also be added (e.g. icebergs). 
    489 \item  \mdl{daymod} 
    490  
    491        No ocean restarts are read or written (though the ice model restarts are retained), so calls to restart functions 
     457\item  \mdl{daymod} : No ocean restarts are read or written (though the ice model restarts are retained), so calls to restart functions 
    492458       have been removed.  This also means that the calendar cannot be controlled by time in a restart file, so the user 
    493459       must make sure that nn{\_}date0 in the model namelist is correct for his or her purposes. 
    494 \item  \mdl{stpctl} 
    495  
    496        Since there is no free surface solver, references to it have been removed from \rou{stp\_ctl} module. 
    497 \item  \mdl{diawri} 
    498  
    499        All 3D data have been removed from the output.  The surface temperature, salinity and velocity components (which 
     460\item  \mdl{stpctl} : Since there is no free surface solver, references to it have been removed from \rou{stp\_ctl} module. 
     461\item  \mdl{diawri} : All 3D data have been removed from the output.  The surface temperature, salinity and velocity components (which 
    500462       have been read in) are written along with relevant forcing and ice data. 
    501 \end{enumerate} 
     463\end{itemize} 
    502464 
    503465One new routine has been added: 
    504466 
    505 \begin{enumerate} 
    506 \item  \mdl{sbcsas} 
    507        This module initialises the input files needed for reading temperature, salinity and velocity arrays at the surface. 
     467\begin{itemize} 
     468\item  \mdl{sbcsas} : This module initialises the input files needed for reading temperature, salinity and velocity arrays at the surface. 
    508469       These filenames are supplied in namelist namsbc{\_}sas.  Unfortunately because of limitations with the \mdl{iom} module, 
    509470       the full 3D fields from the mean files have to be read in and interpolated in time, before using just the top level. 
    510471       Since fldread is used to read in the data, Interpolation on the Fly may be used to change input data resolution. 
    511 \end{enumerate} 
     472\end{itemize} 
     473 
     474 
     475% Missing the description of the 2 following variables: 
     476%   ln_3d_uve   = .true.    !  specify whether we are supplying a 3D u,v and e3 field 
     477%   ln_read_frq = .false.    !  specify whether we must read frq or not 
     478 
     479 
    512480 
    513481% ================================================================ 
    … …  
    590558reanalysis and satellite data. They use an inertial dissipative method to compute  
    591559the turbulent transfer coefficients (momentum, sensible heat and evaporation)  
    592 from the 10 metre wind speed, air temperature and specific humidity. 
     560from the 10 meters wind speed, air temperature and specific humidity. 
    593561This \citet{Large_Yeager_Rep04} dataset is available through the  
    594562\href{http://nomads.gfdl.noaa.gov/nomads/forms/mom4/CORE.html}{GFDL web site}.  
    … …  
    625593or larger than the one of the input atmospheric fields. 
    626594 
     595The  \np{sn\_wndi}, \np{sn\_wndj}, \np{sn\_qsr}, \np{sn\_qlw}, \np{sn\_tair},\np{sn\_humi},\np{sn\_prec}, \np{sn\_snow}, \np{sn\_tdif} parameters describe the fields and the way they have to be used (spatial and temporal interpolations).  
     596 
     597\np{cn\_dir} is the directory of location of bulk files 
     598\np{ln\_taudif} is the flag to specify if we use Hight Frequency (HF) tau information (.true.) or not (.false.) 
     599\np{rn\_zqt}: is the height of humidity and temperature measurements (m) 
     600\np{rn\_zu}: is the height of wind measurements (m) 
     601The multiplicative factors to activate (value is 1) or deactivate (value is 0) :  
     602\np{rn\_pfac} for precipitations (total and snow) 
     603\np{rn\_efac} for evaporation  
     604\np{rn\_vfac} for for ice/ocean velocities in the calculation of wind stress   
     605 
    627606% ------------------------------------------------------------------------------------------------------------- 
    628607%        CLIO Bulk formulea 
    … …  
    720699are sent to the atmospheric component. 
    721700 
    722 A generalised coupled interface has been developed. It is currently interfaced with OASIS 3 
    723 (\key{oasis3}) and does not support OASIS 4 
    724 \footnote{The \key{oasis4} exist. It activates portion of the code that are still under development.}.  
     701A generalised coupled interface has been developed.  
     702It is currently interfaced with OASIS-3-MCT (\key{oasis3}).  
    725703It has been successfully used to interface \NEMO to most of the European atmospheric  
    726704GCM (ARPEGE, ECHAM, ECMWF, HadAM, HadGAM, LMDz),  
    … …  
    787765\label{SBC_tide} 
    788766 
    789 A module is available to use the tidal potential forcing and is activated with with \key{tide}. 
    790  
    791  
    792 %------------------------------------------nam_tide---------------------------------------------------- 
     767%------------------------------------------nam_tide--------------------------------------- 
    793768\namdisplay{nam_tide} 
    794 %------------------------------------------------------------------------------------------------------------- 
    795  
    796 Concerning the tidal potential, some parameters are available in namelist \ngn{nam\_tide}: 
     769%----------------------------------------------------------------------------------------- 
     770 
     771A module is available to compute the tidal potential and use it in the momentum equation. 
     772This option is activated when \key{tide} is defined. 
     773 
     774Some parameters are available in namelist \ngn{nam\_tide}: 
    797775 
    798776- \np{ln\_tide\_pot} activate the tidal potential forcing 
    … …  
    801779 
    802780- \np{clname} is the name of constituent 
    803  
    804781 
    805782The tide is generated by the forces of gravity ot the Earth-Moon and Earth-Sun sytem; 
    … …  
    895872lowest box the river water is being added to (i.e. the total depth that river water is being added to in the model). 
    896873 
     874%Christian: 
     875If the depth information is not provide in the NetCDF file, it can be estimate from the runoff input file at the initial time-step, by setting the namelist parameter \np{ln\_rnf\_depth\_ini} to true. 
     876 
     877This estimation is a simple linear relation between the runoff and a given depth :  
     878\begin{equation}  
     879h\_dep  = \frac{rn\_dep\_max} {rn\_rnf\_max}  rnf 
     880\end{equation} 
     881where  \np{rn\_dep\_max} is the given maximum depth over which the runoffs is spread,  
     882 \np{rn\_rnf\_max} is the maximum value of the runoff climatologie over the global domain 
     883and rnf is the maximum value in time of the runoff climatology at each grid cell (computed online). 
     884 
     885The estimated depth array can be output if needed in a NetCDF file by setting the namelist parameter \np{nn\_rnf\_depth\_file} to 1. 
     886 
    897887The mass/volume addition due to the river runoff is, at each relevant depth level, added to the horizontal divergence  
    898888(\textit{hdivn}) in the subroutine \rou{sbc\_rnf\_div} (called from \mdl{divcur}). 
    … …  
    958948\namdisplay{namsbc_isf} 
    959949%-------------------------------------------------------------------------------------------------------- 
    960 Namelist variable in \ngn{namsbc}, \np{nn\_isf},  control the kind of ice shelf representation used.  
     950Namelist variable in \ngn{namsbc}, \np{nn\_isf}, controls the ice shelf representation used (Fig. \ref{Fig_SBC_isf}):  
     951 
     952%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
     953\begin{figure}[!h]    \begin{center} 
     954\includegraphics[width=0.8\textwidth]{./TexFiles/Figures/Fig_SBC_isf.pdf} 
     955\caption{ \label{Fig_SBC_isf} 
     956Schematic for all the options available trough \np{nn\_isf}.} 
     957\end{center}   \end{figure} 
     958%>>>>>>>>>>>>>>>>>>>>>>>>>>>> 
     959 
    961960\begin{description} 
     961\item[\np{nn\_isf}~=~0] 
     962The ice shelf routines are not used. The ice shelf melting is not computed or prescribed, the cavity have to be closed.  
     963If needed, the ice shelf melting should be added to the runoff or the precipitation file. 
     964 
    962965\item[\np{nn\_isf}~=~1] 
    963 The ice shelf cavity is represented. The fwf and heat flux are computed.  
    964 Full description, sensitivity and validation in preparation.  
     966The ice shelf cavity is represented. The fwf and heat flux are computed. Two different bulk formula are available: 
     967   \begin{description} 
     968   \item[\np{nn\_isfblk}~=~1] 
     969   The bulk formula used to compute the melt is based the one described in \citet{Hunter2006}. 
     970        This formulation is based on a balance between the upward ocean heat flux and the latent heat flux at the ice shelf base. 
     971 
     972   \item[\np{nn\_isfblk}~=~2]  
     973   The bulk formula used to compute the melt is based the one described in \citet{Jenkins1991}. 
     974        This formulation is based on a 3 equations formulation (a heat flux budget, a salt flux budget and a linearised freezing point temperature equation). 
     975   \end{description} 
     976 
     977For this 2 bulk formulations, there are 3 different ways to compute the exchange coeficient: 
     978   \begin{description} 
     979        \item[\np{nn\_gammablk~=~0~}] 
     980   The salt and heat exchange coefficients are constant and defined by \np{rn\_gammas0} and \np{rn\_gammat0} 
     981 
     982   \item[\np{nn\_gammablk~=~1~}] 
     983   The salt and heat exchange coefficients are velocity dependent and defined as $\np{rn\_gammas0} \times u_{*}$ and $\np{rn\_gammat0} \times u_{*}$ 
     984        where $u_{*}$ is the friction velocity in the top boundary layer (ie first \np{rn\_hisf\_tbl} meters). 
     985        See \citet{Jenkins2010} for all the details on this formulation. 
     986    
     987   \item[\np{nn\_gammablk~=~2~}] 
     988   The salt and heat exchange coefficients are velocity and stability dependent and defined as  
     989        $\gamma_{T,S} = \frac{u_{*}}{\Gamma_{Turb} + \Gamma^{T,S}_{Mole}}$ 
     990        where $u_{*}$ is the friction velocity in the top boundary layer (ie first \np{rn\_hisf\_tbl} meters),  
     991        $\Gamma_{Turb}$ the contribution of the ocean stability and  
     992        $\Gamma^{T,S}_{Mole}$ the contribution of the molecular diffusion. 
     993        See \citet{Holland1999} for all the details on this formulation. 
     994        \end{description} 
    965995 
    966996\item[\np{nn\_isf}~=~2] 
    … …  
    968998The fwf is distributed along the ice shelf edge between the depth of the average grounding line (GL) 
    969999(\np{sn\_depmax\_isf}) and the base of the ice shelf along the calving front (\np{sn\_depmin\_isf}) as in (\np{nn\_isf}~=~3).  
    970 Furthermore the fwf is computed using the \citet{Beckmann2003} parameterisation of isf melting.  
     1000Furthermore the fwf and heat flux are computed using the \citet{Beckmann2003} parameterisation of isf melting.  
    9711001The effective melting length (\np{sn\_Leff\_isf}) is read from a file. 
    9721002 
    9731003\item[\np{nn\_isf}~=~3] 
    9741004A simple parameterisation of isf is used. The ice shelf cavity is not represented.  
    975 The fwf (\np{sn\_rnfisf}) is distributed along the ice shelf edge between the depth of the average grounding line (GL) 
    976 (\np{sn\_depmax\_isf}) and the base of the ice shelf along the calving front (\np{sn\_depmin\_isf}). 
    977 Full description, sensitivity and validation in preparation. 
     1005The fwf (\np{sn\_rnfisf}) is prescribed and distributed along the ice shelf edge between the depth of the average grounding line (GL) 
     1006(\np{sn\_depmax\_isf}) and the base of the ice shelf along the calving front (\np{sn\_depmin\_isf}).  
     1007The heat flux ($Q_h$) is computed as $Q_h = fwf \times L_f$. 
    9781008 
    9791009\item[\np{nn\_isf}~=~4] 
    980 The ice shelf cavity is represented. However, the fwf (\np{sn\_fwfisf}) and heat flux (\np{sn\_qisf}) are  
    981 not computed but specified from file.  
     1010The ice shelf cavity is opened. However, the fwf is not computed but specified from file \np{sn\_fwfisf}).  
     1011The heat flux ($Q_h$) is computed as $Q_h = fwf \times L_f$.\\ 
    9821012\end{description} 
    9831013 
    984 \np{nn\_isf}~=~1 and \np{nn\_isf}~=~2 compute a melt rate based on the water masse properties, ocean velocities and depth. 
    985  This flux is thus highly dependent of the model resolution (horizontal and vertical), realism of the water masse onto the shelf ... 
    986  
    987 \np{nn\_isf}~=~3 and \np{nn\_isf}~=~4 read the melt rate and heat flux from a file. You have total control of the fwf scenario. 
    988  
    989  This can be usefull if the water masses on the shelf are not realistic or the resolution (horizontal/vertical) are too  
    990 coarse to have realistic melting or for sensitivity studies where you want to control your input.  
    991 Full description, sensitivity and validation in preparation.  
    992  
    993 There is 2 ways to apply the fwf to NEMO. The first possibility (\np{ln\_divisf}~=~false) applied the fwf 
    994  and heat flux directly on the salinity and temperature tendancy. The second possibility (\np{ln\_divisf}~=~true) 
    995  apply the fwf as for the runoff fwf (see \S\ref{SBC_rnf}). The mass/volume addition due to the ice shelf melting is, 
    996  at each relevant depth level, added to the horizontal divergence (\textit{hdivn}) in the subroutine \rou{sbc\_isf\_div}  
    997 (called from \mdl{divcur}).  
     1014 
     1015$\bullet$ \np{nn\_isf}~=~1 and \np{nn\_isf}~=~2 compute a melt rate based on the water mass properties, ocean velocities and depth. 
     1016 This flux is thus highly dependent of the model resolution (horizontal and vertical), realism of the water masses onto the shelf ...\\ 
     1017 
     1018$\bullet$ \np{nn\_isf}~=~3 and \np{nn\_isf}~=~4 read the melt rate from a file. You have total control of the fwf forcing. 
     1019This can be usefull if the water masses on the shelf are not realistic or the resolution (horizontal/vertical) are too  
     1020coarse to have realistic melting or for studies where you need to control your heat and fw input.\\  
     1021 
     1022Two namelist parameters control how the heat and fw fluxes are passed to NEMO: \np{rn\_hisf\_tbl} and \np{ln\_divisf} 
     1023\begin{description} 
     1024\item[\np{rn\_hisf\_tbl}] is the top boundary layer thickness as defined in \citet{Losch2008}.  
     1025This parameter is only used if \np{nn\_isf}~=~1 or \np{nn\_isf}~=~4 
     1026It allows you to control over which depth you want to spread the heat and fw fluxes.  
     1027 
     1028If \np{rn\_hisf\_tbl} = 0.0, the fluxes are put in the top level whatever is its tickness.  
     1029 
     1030If \np{rn\_hisf\_tbl} $>$ 0.0, the fluxes are spread over the first \np{rn\_hisf\_tbl} m (ie over one or several cells). 
     1031 
     1032\item[\np{ln\_divisf}] is a flag to apply the fw flux as a volume flux or as a salt flux.  
     1033 
     1034\np{ln\_divisf}~=~true applies the fwf as a volume flux. This volume flux is implemented with in the same way as for the runoff. 
     1035The fw addition due to the ice shelf melting is, at each relevant depth level, added to the horizontal divergence  
     1036(\textit{hdivn}) in the subroutine \rou{sbc\_isf\_div}, called from \mdl{divcur}.  
     1037See the runoff section \ref{SBC_rnf} for all the details about the divergence correction.  
     1038 
     1039\np{ln\_divisf}~=~false applies the fwf and heat flux directly on the salinity and temperature tendancy. 
     1040 
     1041\item[\np{ln\_conserve}] is a flag for \np{nn\_isf}~=~1. A conservative boundary layer scheme as described in \citet{Jenkins2001}  
     1042is used if \np{ln\_conserve}=true. It takes into account the fact that the melt water is at freezing T and needs to be warm up to ocean temperature.  
     1043It is only relevant for \np{ln\_divisf}~=~false.  
     1044If \np{ln\_divisf}~=~true, \np{ln\_conserve} has to be set to false to avoid a double counting of the contribution.  
     1045  
     1046\end{description} 
    9981047% 
    9991048% ================================================================ 
    10001049%        Handling of icebergs 
    10011050% ================================================================ 
    1002 \section{ Handling of icebergs (ICB) } 
     1051\section{Handling of icebergs (ICB)} 
    10031052\label{ICB_icebergs} 
    10041053%------------------------------------------namberg---------------------------------------------------- 
    … …  
    10061055%------------------------------------------------------------------------------------------------------------- 
    10071056 
    1008 Icebergs are modelled as lagrangian particles in NEMO. 
    1009 Their physical behaviour is controlled by equations as described in  \citet{Martin_Adcroft_OM10} ). 
    1010 (Note that the authors kindly provided a copy of their code to act as a basis for implementation in NEMO.) 
    1011 Icebergs are initially spawned into one of ten classes which have specific mass and thickness as described in the \ngn{namberg} namelist:  
     1057Icebergs are modelled as lagrangian particles in NEMO \citep{Marsh_GMD2015}. 
     1058Their physical behaviour is controlled by equations as described in \citet{Martin_Adcroft_OM10} ). 
     1059(Note that the authors kindly provided a copy of their code to act as a basis for implementation in NEMO). 
     1060Icebergs are initially spawned into one of ten classes which have specific mass and thickness as described  
     1061in the \ngn{namberg} namelist:  
    10121062\np{rn\_initial\_mass} and \np{rn\_initial\_thickness}. 
    10131063Each class has an associated scaling (\np{rn\_mass\_scaling}), which is an integer representing how many icebergs  
    … …  
    11931243The presence at the sea surface of an ice covered area modifies all the fluxes  
    11941244transmitted to the ocean. There are several way to handle sea-ice in the system  
    1195 depending on the value of the \np{nn{\_}ice} namelist parameter.   
     1245depending on the value of the \np{nn\_ice} namelist parameter found in \ngn{namsbc} namelist.   
    11961246\begin{description} 
    11971247\item[nn{\_}ice = 0]  there will never be sea-ice in the computational domain.  
    … …  
    12681318% ------------------------------------------------------------------------------------------------------------- 
    12691319\subsection   [Neutral drag coefficient from external wave model (\textit{sbcwave})] 
    1270                         {Neutral drag coefficient from external wave model (\mdl{sbcwave})} 
     1320              {Neutral drag coefficient from external wave model (\mdl{sbcwave})} 
    12711321\label{SBC_wave} 
    12721322%------------------------------------------namwave---------------------------------------------------- 
    12731323\namdisplay{namsbc_wave} 
    12741324%------------------------------------------------------------------------------------------------------------- 
    1275 \begin{description} 
    1276  
    1277 \item [??] In order to read a neutral drag coeff, from an external data source (i.e. a wave model), the  
    1278 logical variable \np{ln\_cdgw} 
    1279  in $namsbc$ namelist must be defined ${.true.}$.  
     1325 
     1326In order to read a neutral drag coeff, from an external data source ($i.e.$ a wave model), the  
     1327logical variable \np{ln\_cdgw} in \ngn{namsbc} namelist must be set to \textit{true}.  
    12801328The \mdl{sbcwave} module containing the routine \np{sbc\_wave} reads the 
    12811329namelist \ngn{namsbc\_wave} (for external data names, locations, frequency, interpolation and all  
    12821330the miscellanous options allowed by Input Data generic Interface see \S\ref{SBC_input})  
    1283 and a 2D field of neutral drag coefficient. Then using the routine  
    1284 TURB\_CORE\_1Z or TURB\_CORE\_2Z, and starting from the neutral drag coefficent provided, the drag coefficient is computed according  
    1285 to stable/unstable conditions of the air-sea interface following \citet{Large_Yeager_Rep04}. 
    1286  
    1287 \end{description} 
     1331and a 2D field of neutral drag coefficient.  
     1332Then using the routine TURB\_CORE\_1Z or TURB\_CORE\_2Z, and starting from the neutral drag coefficent provided,  
     1333the drag coefficient is computed according to stable/unstable conditions of the air-sea interface following \citet{Large_Yeager_Rep04}. 
     1334 
    12881335 
    12891336% Griffies doc: 
    1290 % When running ocean-ice simulations, we are not explicitly representing land processes, such as rivers, catchment areas, snow accumulation, etc. However, to reduce model drift, it is important to balance the hydrological cycle in ocean-ice models. We thus need to prescribe some form of global normalization to the precipitation minus evaporation plus river runoff. The result of the normalization should be a global integrated zero net water input to the ocean-ice system over a chosen time scale.  
    1291 %How often the normalization is done is a matter of choice. In mom4p1, we choose to do so at each model time step, so that there is always a zero net input of water to the ocean-ice system. Others choose to normalize over an annual cycle, in which case the net imbalance over an annual cycle is used to alter the subsequent year�s water budget in an attempt to damp the annual water imbalance. Note that the annual budget approach may be inappropriate with interannually varying precipitation forcing.  
    1292 %When running ocean-ice coupled models, it is incorrect to include the water transport between the ocean and ice models when aiming to balance the hydrological cycle. The reason is that it is the sum of the water in the ocean plus ice that should be balanced when running ocean-ice models, not the water in any one sub-component. As an extreme example to illustrate the issue, consider an ocean-ice model with zero initial sea ice. As the ocean-ice model spins up, there should be a net accumulation of water in the growing sea ice, and thus a net loss of water from the ocean. The total water contained in the ocean plus ice system is constant, but there is an exchange of water between the subcomponents. This exchange should not be part of the normalization used to balance the hydrological cycle in ocean-ice models.  
    1293  
    1294  
     1337% When running ocean-ice simulations, we are not explicitly representing land processes,  
     1338% such as rivers, catchment areas, snow accumulation, etc. However, to reduce model drift,  
     1339% it is important to balance the hydrological cycle in ocean-ice models.  
     1340% We thus need to prescribe some form of global normalization to the precipitation minus evaporation plus river runoff.  
     1341% The result of the normalization should be a global integrated zero net water input to the ocean-ice system over  
     1342% a chosen time scale.  
     1343%How often the normalization is done is a matter of choice. In mom4p1, we choose to do so at each model time step,  
     1344% so that there is always a zero net input of water to the ocean-ice system.  
     1345% Others choose to normalize over an annual cycle, in which case the net imbalance over an annual cycle is used  
     1346% to alter the subsequent year�s water budget in an attempt to damp the annual water imbalance.  
     1347% Note that the annual budget approach may be inappropriate with interannually varying precipitation forcing.  
     1348% When running ocean-ice coupled models, it is incorrect to include the water transport between the ocean  
     1349% and ice models when aiming to balance the hydrological cycle.  
     1350% The reason is that it is the sum of the water in the ocean plus ice that should be balanced when running ocean-ice models,  
     1351% not the water in any one sub-component. As an extreme example to illustrate the issue,  
     1352% consider an ocean-ice model with zero initial sea ice. As the ocean-ice model spins up,  
     1353% there should be a net accumulation of water in the growing sea ice, and thus a net loss of water from the ocean.  
     1354% The total water contained in the ocean plus ice system is constant, but there is an exchange of water between  
     1355% the subcomponents. This exchange should not be part of the normalization used to balance the hydrological cycle  
     1356% in ocean-ice models.  
     1357 
     1358 
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