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2019-12-04T16:52:57+01:00 (12 months ago)
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Writing the doc for SBCBLK!

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 r12046 % aerodynamic bulk formulae: Note: all the NEMO Fortran routines involved in the present section have been initially developed (and are still developped in parallel) in the \href{https://brodeau.github.io/aerobulk/}{\texttt{AeroBulk}} open-source project \citep{brodeau.barnier.ea_JPO17}. %%% Bulk formulae are this: \subsection{Bulk formulae} \subsection{Bulk formulae}\label{subsec:SBC_blkform} % In NEMO, the set of equations that relate each component of the surface fluxes $\rho$ is the density of air. $C_D$, $C_H$ and $C_E$ are the bulk transfer coefficients for momentum, sensible heat, and moisture, respectively (hereafter referd to as BTCs). referred to as BTCs). % $C_P$ is the heat capacity of moist air, and $L_v$ is the latent heat of respectively. $\gamma z$ is a temperature correction term which accounts for the adiabatic lapse rate and approximates the potential temperature at height $z$ \citep{Josey_al_2013}. $z$ \citep{josey.gulev.ea_2013}. % $\mathbf{U}_z$ is the wind speed vector at height $z$ above the sea surface % The bulk scalar wind speed, namely $U_B$, is the scalar wind speed, $|\mathbf{U}_z|$, with the potential inclusion of a gustiness contribution (section \ref{s_res2}.\ref{ss_calm}). $|\mathbf{U}_z|$, with the potential inclusion of a gustiness contribution . % $a$ and $\delta$ are the albedo and emissivity of the sea surface, respectively.\\ $T_s$ is the sea surface temperature. $q_s$ is the saturation specific humidity of air at temperature $T_s$ and includes a 2\% reduction to account for the presence of salt in seawater \citep{Sverdrup_al_1942,Kraus_Businger_1996}. Depending on the bulk parameterization used, $T_s$ can either be the temperature presence of salt in seawater \citep{sverdrup.johnson.ea_1942,kraus.businger_QJRMS96}. Depending on the bulk parametrization used, $T_s$ can either be the temperature at the air-sea interface (skin temperature, hereafter SSST) or at typically a few tens of centimeters below the surface (bulk sea surface temperature, The SSST differs from the SST due to the contributions of two effects of opposite sign, the \emph{cool skin} and \emph{warm layer} (hereafter CS and WL, respectively). % Technically, when the ECMWF or COARE* bulk parameterizations are selected respectively, see section\,\ref{subsec:SBC_skin}). % Technically, when the ECMWF or COARE* bulk parametrizations are selected (\np[=.true.]{ln_ECMWF}{ln\_ECMWF} or \np[=.true.]{ln_COARE*}{ln\_COARE\*}), $T_s$ is the SSST, as opposed to the NCAR bulk parameterization $T_s$ is the SSST, as opposed to the NCAR bulk parametrization (\np[=.true.]{ln_NCAR}{ln\_NCAR}) for which $T_s$ is the bulk SST (\ie~temperature at first T-point level). \subsection{Bulk parameterizations} \subsection{Bulk parametrizations}\label{subsec:SBC_blk_ocean} %%%\label{subsec:SBC_param} Accuracy of the estimate of surface turbulent fluxes by means of bulk formulae strongly relies on that of the bulk transfer coefficients: $C_D$, $C_H$ and $C_E$. They are estimated with what we refer to as a \emph{bulk parameterization} algorithm. ... also to adjust humidity and temperature of air to the wind reference measurement height (generally 10\,m). Over the open ocean, four bulk parameterization algorithms are available: parametrization} algorithm. When relevant, these algorithms also perform the height adjustment of humidity and temperature to the wind reference measurement height (from \np{rn_zqt}{rn\_zqt} to \np{rn_zu}{rn\_zu}). For the open ocean, four bulk parametrization algorithms are available: \begin{itemize} \item NCAR, formerly known as CORE, \citep{large.yeager_rpt04} \item NCAR, formerly known as CORE, \citep{large.yeager_rpt04,large.yeager_CD09} \item COARE 3.0 \citep{fairall.bradley.ea_JC03} \item COARE 3.6 \citep{edson.jampana.ea_JPO13} \item ECMWF (IFS documentation, cy41) \item ECMWF (IFS documentation, cy45) \end{itemize} \subsubsection{Appropriate use of the  NCAR algorithm} NCAR bulk parameterizations (formerly know as CORE) is meant to be used with the Differences between versions 3.0 and 3.6 of the COARE algorithm mainly ... wind stress BLABLA \citep{edson.jampana.ea_JPO13,brodeau.barnier.ea_JPO17}. Therefore it is recommanded to use version 3.6 of the COARE algorithms rather than version 3. \subsection{Cool-skin and warm-layer parametrizations}\label{subsec:SBC_skin} %\subsection[Cool-skin and warm-layer parameterizations %(\forcode{ln_skin_cs} \& \forcode{ln_skin_wl})]{Cool-skin and warm-layer parameterizations (\protect\np{ln_skin_cs}{ln\_skin\_cs} \& \np{ln_skin_wl}{ln\_skin\_wl})} %\label{subsec:SBC_skin} % As opposed to the NCAR bulk parametrization, more advanced bulk parametrizations such as COARE3.x and ECMWF are meant to be used with the skin temperature $T_s$ rather than the bulk SST (which, in NEMO is the temperature at the first T-point level, see section\,\ref{subsec:SBC_blkform}). % As such, the relevant cool-skin and warm-layer parametrization must be activated through \np[=T]{ln_skin_cs}{ln\_skin\_cs} and \np[=T]{ln_skin_wl}{ln\_skin\_wl} to use COARE3.x or ECMWF in a consistent way. \texttt{\#LB: ADD BLBLA ABOUT THE TWO CS/WL PARAMETRIZATIONS (ECMWF and COARE) !!!} For the cool-skin scheme parametrization COARE and ECMWF algorithms share the same basis: \citet{fairall.bradley.ea_JGR96}. With some minor updates based on \citet{zeng.beljaars_GRL05} for ECMWF, and \citet{fairall.ea_19} for COARE 3.6. For the warm-layer scheme, ECMWF is based on \citet{zeng.beljaars_GRL05} with a recent update from \citet{takaya.bidlot.ea_JGR10} (consideration of the turbulence input from Langmuir circulation). Importantly, COARE warm-layer scheme \citep{fairall.ea_19} includes a prognostic equation for the thickness of the warm-layer, while it is considered as constant in the ECWMF algorithm. \subsection{Appropriate use of each bulk parametrization} \subsubsection{NCAR} NCAR bulk parametrizations (formerly know as CORE) is meant to be used with the CORE II atmospheric forcing \citep{large.yeager_CD09}. Hence the following namelist parameters must be set: \subsubsection{Appropriate use of the ECMWF algorithm} \subsubsection{ECMWF} % With a DFS* or any ECMWF-based type of atmospheric forcing, we strongly recommand to use the ECMWF bulk parameterizations with the cool-skin and warm-layer parameterizations turned on. In ECMWF reanalyzes, since air temperature and humidity are provided at the 2\,m height, and that the humidity is provided as a dew-point temperature, the namelist must be tuned as follows: recommend to use the ECMWF bulk parametrizations with the cool-skin and warm-layer parametrizations turned on. In ECMWF reanalyzes, since air temperature and humidity are provided at the 2\,m height, and given that the humidity is provided as the dew-point temperature, the namelist must be tuned as follows: % \begin{verbatim} ... \end{verbatim} % Note: when \np{ln_ECMWF}{ln\_ECMWF} is selected, the selection of \np{ln_skin_cs}{ln\_skin\_cs} and \np{ln_skin_wl}{ln\_skin\_wl} implicitely triggers the use of the ECMWF cool-skin and warm-layer parameterizations, of \np{ln_skin_cs}{ln\_skin\_cs} and \np{ln_skin_wl}{ln\_skin\_wl} implicitly triggers the use of the ECMWF cool-skin and warm-layer parametrizations, respectively (found in \textit{sbcblk\_skin\_ecmwf.F90}). \subsubsection{Appropriate use of the COARE 3.x algorithms} \subsubsection{COARE 3.x} % Since the ECMWF parametrization is largely based on the COARE* parametrization, the two algorithms are very similar in terms of structure and closure approach (see \citet{brodeau.barnier.ea_JPO17} for the differences). As such, the namelist tuning for COARE 3.x is identical to that of ECMWF: % \begin{verbatim} ... \end{verbatim} Note: when \np{ln_COARE3pX}{ln\_COARE3pX} is selected, the selection of \np{ln_skin_cs}{ln\_skin\_cs} and \np{ln_skin_wl}{ln\_skin\_wl} implicitely triggers the use of the COARE cool-skin and warm-layer parameterizations, Note: when \np[=T]{ln_COARE3p0}{ln\_COARE3p0} is selected, the selection of \np{ln_skin_cs}{ln\_skin\_cs} and \np{ln_skin_wl}{ln\_skin\_wl} implicitly triggers the use of the COARE cool-skin and warm-layer parametrizations, respectively (found in \textit{sbcblk\_skin\_coare.F90}). \subsection[Cool-skin and warm-layer parameterizations (\forcode{ln_skin_cs} \& \forcode{ln_skin_wl})]{Cool-skin and warm-layer parameterizations (\protect\np{ln_skin_cs}{ln\_skin\_cs} \& \np{ln_skin_wl}{ln\_skin\_wl})} \label{subsec:SBC_skin} As oposed to the NCAR bulk parameterization, more advanced bulk parameterizations such as COARE3.x and ECMWF are meant to be used with the skin temperature $T_s$ rather than the bulk SST (which, in NEMO is the temperature at the first T-point level). % So that, technically, the cool-skin and warm-layer parameterization must be activated (XXX) to use COARE3.x and ECMWF in a consistant way. \subsection{Air humidity} Air humidity can be provided as three different parameters: specific humidity [kg/kg], relative humidity [\%], or dew-point temperature [K] (LINK to namelist parameters)... ~\\ \subsection{Prescribed near-surface atmospheric state} The atmospheric fields used depend on the bulk formulae used.  In forced mode, % thanks to the \href{https://brodeau.github.io/aerobulk/}{Aerobulk} package (\citet{brodeau.barnier.ea_JPO17}): The choice is made by setting to true one of the following namelist variable: \np{ln_NCAR}{ln\_NCAR}, \np{ln_COARE_3p0}{ln\_COARE\_3p0}, \np{ln_COARE_3p6}{ln\_COARE\_3p6} and \np{ln_ECMWF}{ln\_ECMWF}.  For sea-ice, three possibilities can be selected: a constant transfer coefficient (1.4e-3; default value), \citet{lupkes.gryanik.ea_JGR12} (\np{ln_Cd_L12}{ln\_Cd\_L12}), and \citet{lupkes.gryanik_JGR15} (\np{ln_Cd_L15}{ln\_Cd\_L15}) parameterizations %The choice is made by setting to true one of the following namelist %variable: \np{ln_NCAR}{ln\_NCAR}, \np{ln_COARE_3p0}{ln\_COARE\_3p0}, \np{ln_COARE_3p6}{ln\_COARE\_3p6} %and \np{ln_ECMWF}{ln\_ECMWF}. Common options are defined through the \nam{sbc_blk}{sbc\_blk} namelist variables. the namsbc\_blk namelist (see \autoref{subsec:SBC_fldread}). %% ================================================================================================= \subsection[Ocean-Atmosphere Bulk formulae (\textit{sbcblk\_algo\_coare3p0.F90, sbcblk\_algo\_coare3p6.F90, sbcblk\_algo\_ecmwf.F90, sbcblk\_algo\_ncar.F90})]{Ocean-Atmosphere Bulk formulae (\mdl{sbcblk\_algo\_coare3p0}, \mdl{sbcblk\_algo\_coare3p6}, \mdl{sbcblk\_algo\_ecmwf}, \mdl{sbcblk\_algo\_ncar})} \label{subsec:SBC_blk_ocean} Four different bulk algorithms are available to compute surface turbulent momentum and heat fluxes over the ocean. COARE 3.0, COARE 3.6 and ECMWF schemes mainly differ by their roughness lenghts computation and consequently their neutral transfer coefficients relationships with neutral wind. \begin{itemize} \item NCAR (\np[=.true.]{ln_NCAR}{ln\_NCAR}): The NCAR bulk formulae have been developed by \citet{large.yeager_rpt04}. They have been designed to handle the NCAR forcing, a mixture of NCEP reanalysis and satellite data. They use an inertial dissipative method to compute the turbulent transfer coefficients (momentum, sensible heat and evaporation) from the 10m wind speed, air temperature and specific humidity. This \citet{large.yeager_rpt04} dataset is available through the \href{http://nomads.gfdl.noaa.gov/nomads/forms/mom4/NCAR.html}{GFDL web site}. Note that substituting ERA40 to NCEP reanalysis fields does not require changes in the bulk formulea themself. This is the so-called DRAKKAR Forcing Set (DFS) \citep{brodeau.barnier.ea_OM10}. \item COARE 3.0 (\np[=.true.]{ln_COARE_3p0}{ln\_COARE\_3p0}): See \citet{fairall.bradley.ea_JC03} for more details \item COARE 3.6 (\np[=.true.]{ln_COARE_3p6}{ln\_COARE\_3p6}): See \citet{edson.jampana.ea_JPO13} for more details \item ECMWF (\np[=.true.]{ln_ECMWF}{ln\_ECMWF}): Based on \href{https://www.ecmwf.int/node/9204}{IFS (Cy40r1)} implementation and documentation. Surface roughness lengths needed for the Obukhov length are computed following \citet{beljaars_QJRMS95}. \end{itemize} \subsubsection{Air humidity} Air humidity can be provided as three different parameters: specific humidity [kg/kg], relative humidity [\%], or dew-point temperature [K] (LINK to namelist parameters)... ~\\ %% ================================================================================================= %\subsection[Ocean-Atmosphere Bulk formulae (\textit{sbcblk\_algo\_coare3p0.F90, sbcblk\_algo\_coare3p6.F90, %sbcblk\_algo\_ecmwf.F90, sbcblk\_algo\_ncar.F90})]{Ocean-Atmosphere Bulk formulae (\mdl{sbcblk\_algo\_coare3p0}, %\mdl{sbcblk\_algo\_coare3p6}, \mdl{sbcblk\_algo\_ecmwf}, \mdl{sbcblk\_algo\_ncar})} %\label{subsec:SBC_blk_ocean} %Four different bulk algorithms are available to compute surface turbulent momentum and heat fluxes over the ocean. %COARE 3.0, COARE 3.6 and ECMWF schemes mainly differ by their roughness lenghts computation and consequently %their neutral transfer coefficients relationships with neutral wind. %\begin{itemize} %\item NCAR (\np[=.true.]{ln_NCAR}{ln\_NCAR}): The NCAR bulk formulae have been developed by \citet{large.yeager_rpt04}. %  They have been designed to handle the NCAR forcing, a mixture of NCEP reanalysis and satellite data. %  They use an inertial dissipative method to compute the turbulent transfer coefficients %  (momentum, sensible heat and evaporation) from the 10m wind speed, air temperature and specific humidity. %  This \citet{large.yeager_rpt04} dataset is available through %  the \href{http://nomads.gfdl.noaa.gov/nomads/forms/mom4/NCAR.html}{GFDL web site}. %  Note that substituting ERA40 to NCEP reanalysis fields does not require changes in the bulk formulea themself. %  This is the so-called DRAKKAR Forcing Set (DFS) \citep{brodeau.barnier.ea_OM10}. %\item COARE 3.0 (\np[=.true.]{ln_COARE_3p0}{ln\_COARE\_3p0}): See \citet{fairall.bradley.ea_JC03} for more details %\item COARE 3.6 (\np[=.true.]{ln_COARE_3p6}{ln\_COARE\_3p6}): See \citet{edson.jampana.ea_JPO13} for more details %\item ECMWF (\np[=.true.]{ln_ECMWF}{ln\_ECMWF}): Based on \href{https://www.ecmwf.int/node/9204}{IFS (Cy40r1)} %implementation and documentation. %  Surface roughness lengths needed for the Obukhov length are computed %  following \citet{beljaars_QJRMS95}. %\end{itemize} %% ================================================================================================= \subsection{Ice-Atmosphere Bulk formulae} \label{subsec:SBC_blk_ice} \texttt{\#out\_of\_place:} For sea-ice, three possibilities can be selected: a constant transfer coefficient (1.4e-3; default value), \citet{lupkes.gryanik.ea_JGR12} (\np{ln_Cd_L12}{ln\_Cd\_L12}), and \citet{lupkes.gryanik_JGR15} (\np{ln_Cd_L15}{ln\_Cd\_L15}) parameterizations \texttt{\#out\_of\_place.} Surface turbulent fluxes between sea-ice and the atmosphere can be computed in three different ways: