Changeset 3294 for trunk/DOC/TexFiles/Chapters/Chap_SBC.tex

Timestamp:

2012-01-28T17:44:18+01:00 (12 years ago)

Author:

rblod

Message:

Merge of 3.4beta into the trunk

File:

• trunk/DOC/TexFiles/Chapters/Chap_SBC.tex (modified) (13 diffs, 1 prop)

trunk/DOC/TexFiles/Chapters/Chap_SBC.tex

@@ -24 +24 @@
 \end{itemize}
 
-Four different ways to provide the first six fields to the ocean are available which 
+Five different ways to provide the first six fields to the ocean are available which 
 are controlled by namelist variables: an analytical formulation (\np{ln\_ana}~=~true), 
 a flux formulation (\np{ln\_flx}~=~true), a bulk formulae formulation (CORE 
-(\np{ln\_core}~=~true) or CLIO (\np{ln\_clio}~=~true) bulk formulae) and a coupled 
+(\np{ln\_core}~=~true), CLIO (\np{ln\_clio}~=~true) or MFS
+\footnote { Note that MFS bulk formulae compute fluxes only for the ocean component}
+(\np{ln\_mfs}~=~true) bulk formulae) and a coupled 
 formulation (exchanges with a atmospheric model via the OASIS coupler) 
 (\np{ln\_cpl}~=~true). When used, the atmospheric pressure forces both 
-ocean and ice dynamics (\np{ln\_apr\_dyn}~=~true)
-\footnote{The surface pressure field could be use in bulk formulae, nevertheless 
-none of the current bulk formulea (CLIO and CORE) uses the it.}. 
+ocean and ice dynamics (\np{ln\_apr\_dyn}~=~true).
 The frequency at which the six or seven fields have to be updated is the \np{nn\_fsbc} 
 namelist parameter. 
@@ -46 +46 @@
 (\np{nn\_ice}~=~0,1, 2 or 3); the addition of river runoffs as surface freshwater 
 fluxes or lateral inflow (\np{ln\_rnf}~=~true); the addition of a freshwater flux adjustment 
-in order to avoid a mean sea-level drift (\np{nn\_fwb}~=~0,~1~or~2); and the 
+in order to avoid a mean sea-level drift (\np{nn\_fwb}~=~0,~1~or~2); the 
 transformation of the solar radiation (if provided as daily mean) into a diurnal 
-cycle (\np{ln\_dm2dc}~=~true).
+cycle (\np{ln\_dm2dc}~=~true); and a neutral drag coefficient can be read from an external wave 
+model (\np{ln\_cdgw}~=~true). The latter option is possible only in case core or mfs bulk formulas are selected.
 
 In this chapter, we first discuss where the surface boundary condition appears in the
-model equations. Then we present the four ways of providing the surface boundary condition, 
+model equations. Then we present the five ways of providing the surface boundary condition, 
 followed by the description of the atmospheric pressure and the river runoff. 
 Next the scheme for interpolation on the fly is described.
@@ -245 +246 @@
 actual year/month/day, always coded with 4 or 2 digits. Note that (1) in mpp, if the file is split 
 over each subdomain, the suffix '.nc' is replaced by '\_PPPP.nc', where 'PPPP' is the 
-process number coded with 4 digits; (2) when using AGRIF, the prefix ÔN\_Õ is added to files, 
+process number coded with 4 digits; (2) when using AGRIF, the prefix
+'\_N' is added to files, 
 where 'N'  is the child grid number.}
 \end{table}
@@ -480 +482 @@
 % Bulk formulation
 % ================================================================
-\section  [Bulk formulation (\textit{sbcblk\_core} or \textit{sbcblk\_clio}) ]
-      {Bulk formulation \small{(\mdl{sbcblk\_core} or \mdl{sbcblk\_clio} module)} }
+\section  [Bulk formulation (\textit{sbcblk\_core}, \textit{sbcblk\_clio} or \textit{sbcblk\_mfs}) ]
+      {Bulk formulation \small{(\mdl{sbcblk\_core} \mdl{sbcblk\_clio} \mdl{sbcblk\_mfs} modules)} }
 \label{SBC_blk}
 
@@ -487 +489 @@
 using bulk formulae and atmospheric fields and ocean (and ice) variables. 
 
-The atmospheric fields used depend on the bulk formulae used. Two bulk formulations 
-are available : the CORE and CLIO bulk formulea. The choice is made by setting to true
-one of the following namelist variable : \np{ln\_core} and \np{ln\_clio}.
-
-Note : in forced mode, when a sea-ice model is used, a bulk formulation have to be used. 
-Therefore the two bulk formulea provided include the computation of the fluxes over both 
+The atmospheric fields used depend on the bulk formulae used. Three bulk formulations 
+are available : the CORE, the CLIO and the MFS bulk formulea. The choice is made by setting to true
+one of the following namelist variable : \np{ln\_core} ; \np{ln\_clio} or  \np{ln\_mfs}.
+
+Note : in forced mode, when a sea-ice model is used, a bulk formulation (CLIO or CORE) have to be used. 
+Therefore the two bulk (CLIO and CORE) formulea include the computation of the fluxes over both 
 an ocean and an ice surface. 
 
@@ -583 +585 @@
 namelist (see \S\ref{SBC_fldread}). 
 
+% -------------------------------------------------------------------------------------------------------------
+%        MFS Bulk formulae
+% -------------------------------------------------------------------------------------------------------------
+\subsection    [MFS Bulk formulea (\np{ln\_mfs}=true)]
+            {MFS Bulk formulea (\np{ln\_mfs}=true, \mdl{sbcblk\_mfs})}
+\label{SBC_blk_mfs}
+%------------------------------------------namsbc_mfs----------------------------------------------------
+\namdisplay{namsbc_mfs} 
+%----------------------------------------------------------------------------------------------------------
+
+The MFS (Mediterranean Forecasting System) bulk formulae have been developed by
+ \citet{Castellari_al_JMS1998}. 
+They have been designed to handle the ECMWF operational data and are currently 
+in use in the MFS operational system \citep{Tonani_al_OS08}, \citep{Oddo_al_OS09}.
+The wind stress computation uses a drag coefficient computed according to \citet{Hellerman_Rosenstein_JPO83}.
+The surface boundary condition for temperature involves the balance between surface solar radiation,
+net long-wave radiation, the latent and sensible heat fluxes.
+Solar radiation is dependent on cloud cover and is computed by means of
+an astronomical formula \citep{Reed_JPO77}. Albedo monthly values are from \citet{Payne_JAS72} 
+as means of the values at $40^{o}N$ and $30^{o}N$ for the Atlantic Ocean (hence the same latitudinal
+band of the Mediterranean Sea). The net long-wave radiation flux
+\citep{Bignami_al_JGR95} is a function of
+air temperature, sea-surface temperature, cloud cover and relative humidity.
+Sensible heat and latent heat fluxes are computed by classical
+bulk formulae parameterized according to \citet{Kondo1975}.
+Details on the bulk formulae used can be found in \citet{Maggiore_al_PCE98} and \citet{Castellari_al_JMS1998}.
+
+The required 7 input fields must be provided on the model Grid-T and  are:
+\begin{itemize}
+\item          Zonal Component of the 10m wind ($ms^{-1}$)  (\np{sn\_windi})
+\item          Meridional Component of the 10m wind ($ms^{-1}$)  (\np{sn\_windj})
+\item          Total Claud Cover (\%)  (\np{sn\_clc})
+\item          2m Air Temperature ($K$) (\np{sn\_tair})
+\item          2m Dew Point Temperature ($K$)  (\np{sn\_rhm})
+\item          Total Precipitation ${Kg} m^{-2} s^{-1}$ (\np{sn\_prec})
+\item          Mean Sea Level Pressure (${Pa}$) (\np{sn\_msl})
+\end{itemize}
+% -------------------------------------------------------------------------------------------------------------
 % ================================================================
 % Coupled formulation
@@ -602 +642 @@
 \footnote{The \key{oasis4} exist. It activates portion of the code that are still under development.}. 
 It has been successfully used to interface \NEMO to most of the European atmospheric 
-GCM (ARPEGE, ECHAM, ECMWF, HadAM, LMDz), 
+GCM (ARPEGE, ECHAM, ECMWF, HadAM, HadGAM, LMDz), 
 as well as to \href{http://wrf-model.org/}{WRF} (Weather Research and Forecasting Model).
 
@@ -610 +650 @@
 When PISCES biogeochemical model (\key{top} and \key{pisces}) is also used in the coupled system, 
 the whole carbon cycle is computed by defining \key{cpl\_carbon\_cycle}. In this case, 
-CO$_2$ fluxes are exchanged between the atmosphere and the ice-ocean system.
+CO$_2$ fluxes will be exchanged between the atmosphere and the ice-ocean system (and need to be activated
+in namsbc{\_}cpl).
+
+The new namelist above allows control of various aspects of the coupling fields (particularly for
+vectors) and now allows for any coupling fields to have multiple sea ice categories (as required by LIM3
+and CICE).  When indicating a multi-category coupling field in namsbc{\_}cpl the number of categories will be
+determined by the number used in the sea ice model.  In some limited cases it may be possible to specify 
+single category coupling fields even when the sea ice model is running with multiple categories - in this
+case the user should examine the code to be sure the assumptions made are satisfactory.  In cases where
+this is definitely not possible the model should abort with an error message.  The new code has been tested using
+ECHAM with LIM2, and HadGAM3 with CICE but although it will compile with \key{lim3} additional minor code changes
+may be required to run using LIM3.
 
 
@@ -645 +696 @@
 
 % ================================================================
+%        Tidal Potential
+% ================================================================
+\section   [Tidal Potential (\textit{sbctide})]
+                        {Tidal Potential (\mdl{sbctide})}
+\label{SBC_tide}
+
+A module is available to use the tidal potential forcing and is activated with with \key{tide}.
+
+
+%------------------------------------------nam_tide----------------------------------------------------
+\namdisplay{nam_tide}
+%-------------------------------------------------------------------------------------------------------------
+
+Concerning the tidal potential, some parameters are available in namelist:
+
+- \texttt{ln\_tide\_pot} activate the tidal potential forcing
+
+- \texttt{nb\_harmo} is the number of constituent used
+
+- \texttt{clname} is the name of constituent
+
+
+The tide is generated by the forces of gravity ot the Earth-Moon and Earth-Sun sytem;
+they are expressed as the gradient of the astronomical potential ($\vec{\nabla}\Pi_{a}$). \\
+
+The potential astronomical expressed, for the three types of tidal frequencies
+following, by : \\
+Tide long period :
+\begin{equation}
+\Pi_{a}=gA_{k}(\frac{1}{2}-\frac{3}{2}sin^{2}\phi)cos(\omega_{k}t+V_{0k})
+\end{equation}
+diurnal Tide :
+\begin{equation}
+\Pi_{a}=gA_{k}(sin 2\phi)cos(\omega_{k}t+\lambda+V_{0k})
+\end{equation}
+Semi-diurnal tide:
+\begin{equation}
+\Pi_{a}=gA_{k}(cos^{2}\phi)cos(\omega_{k}t+2\lambda+V_{0k})
+\end{equation}
+
+
+$A_{k}$ is the amplitude of the wave k, $\omega_{k}$ the pulsation of the wave k, $V_{0k}$ the astronomical phase of the wave
+$k$ to Greenwich.
+
+We make corrections to the astronomical potential.
+We obtain : 
+\begin{equation}
+\Pi-g\delta = (1+k-h) \Pi_{A}(\lambda,\phi)
+\end{equation}
+with $k$ a number of Love estimated to 0.6 which parametrized the astronomical tidal land,
+and $h$ a number of Love to 0.3 which parametrized the parametrization due to the astronomical tidal land.
+
+% ================================================================
 %        River runoffs
 % ================================================================
@@ -759 +863 @@
 %To do this we need to treat evaporation/precipitation fluxes and river runoff differently in the tra_sbc module.  We decided to separate them throughout the code, so that the variable emp represented solely evaporation minus precipitation fluxes, and a new 2d variable rnf was added which represents the volume flux of river runoff (in kg/m2s to remain consistent with emp).  This meant many uses of emp and emps needed to be changed, a list of all modules which use emp or emps and the changes made are below:
 
-}
+%}
 
 % ================================================================
@@ -909 +1013 @@
 ice-ocean fluxes, that are combined with the air-sea fluxes using the ice fraction of 
 each model cell to provide the surface ocean fluxes. Note that the activation of a 
-sea-ice model is is done by defining a CPP key (\key{lim2} or \key{lim3}). 
-The activation automatically ovewrite the read value of nn{\_}ice to its appropriate 
-value ($i.e.$ $2$ for LIM-2 and $3$ for LIM-3).
+sea-ice model is is done by defining a CPP key (\key{lim2}, \key{lim3} or \key{cice}). 
+The activation automatically overwrites the read value of nn{\_}ice to its appropriate 
+value ($i.e.$ $2$ for LIM-2, $3$ for LIM-3 or $4$ for CICE).
 \end{description}
 
 % {Description of Ice-ocean interface to be added here or in LIM 2 and 3 doc ?}
+
+\subsection   [Interface to CICE (\textit{sbcice\_cice})]
+         {Interface to CICE (\mdl{sbcice\_cice})}
+\label{SBC_cice}
+
+It is now possible to couple a global NEMO configuration (without AGRIF) to the CICE sea-ice
+model by using \key{cice}.  The CICE code can be obtained from 
+\href{http://oceans11.lanl.gov/trac/CICE/}{LANL} and the additional 'hadgem3' drivers will be required, 
+even with the latest code release.  Input grid files consistent with those used in NEMO will also be needed, 
+and CICE CPP keys \textbf{ORCA\_GRID}, \textbf{CICE\_IN\_NEMO} and \textbf{coupled} should be used (seek advice from UKMO 
+if necessary).  Currently the code is only designed to work when using the CORE forcing option for NEMO (with
+\textit{calc\_strair~=~true} and \textit{calc\_Tsfc~=~true} in the CICE name-list), or alternatively when NEMO 
+is coupled to the HadGAM3 atmosphere model (with \textit{calc\_strair~=~false} and \textit{calc\_Tsfc~=~false}).
+The code is intended to be used with \np{nn\_fsbc} set to 1 (although coupling ocean and ice less frequently 
+should work, it is possible the calculation of some of the ocean-ice fluxes needs to be modified slightly - the
+user should check that results are not significantly different to the standard case).
+
+There are two options for the technical coupling between NEMO and CICE.  The standard version allows
+complete flexibility for the domain decompositions in the individual models, but this is at the expense of global
+gather and scatter operations in the coupling which become very expensive on larger numbers of processors. The
+alternative option (using \key{nemocice\_decomp} for both NEMO and CICE) ensures that the domain decomposition is
+identical in both models (provided domain parameters are set appropriately, and 
+\textit{processor\_shape~=~square-ice} and \textit{distribution\_wght~=~block} in the CICE name-list) and allows
+much more efficient direct coupling on individual processors.  This solution scales much better although it is at 
+the expense of having more idle CICE processors in areas where there is no sea ice.
+
 
 % -------------------------------------------------------------------------------------------------------------
@@ -938 +1068 @@
 \end{description}
 
+% -------------------------------------------------------------------------------------------------------------
+%        Neutral Drag Coefficient from external wave model
+% -------------------------------------------------------------------------------------------------------------
+\subsection   [Neutral drag coefficient from external wave model (\textit{sbcwave})]
+                        {Neutral drag coefficient from external wave model (\mdl{sbcwave})}
+\label{SBC_wave}
+%------------------------------------------namwave----------------------------------------------------
+\namdisplay{namsbc_wave}
+%-------------------------------------------------------------------------------------------------------------
+\begin{description}
+
+\item [??] In order to read a neutral drag coeff, from an external data source (i.e. a wave model), the 
+logical variable \np{ln\_cdgw}
+ in $namsbc$ namelist must be defined ${.true.}$. 
+The \mdl{sbcwave} module containing the routine \np{sbc\_wave} reads the
+namelist ${namsbc\_wave}$ (for external data names, locations, frequency, interpolation and all 
+the miscellanous options allowed by Input Data generic Interface see \S\ref{SBC_input}) 
+and a 2D field of neutral drag coefficient. Then using the routine 
+TURB\_CORE\_1Z or TURB\_CORE\_2Z, and starting from the neutral drag coefficent provided, the drag coefficient is computed according 
+to stable/unstable conditions of the air-sea interface following \citet{Large_Yeager_Rep04}.
+
+\end{description}
+
 % Griffies doc:
 % 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. 
@@ -944 +1097 @@
 
 
-