s_phys_pkgs/text/rbcs.tex

\subsection {RBCS Package} 
\label{sec:pkg:rbcs}
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\subsubsection {Introduction}

A package which provides the flexibility
to relax fields (temperature, salinity, ptracers)
in any 3-D location:
so could be used as a sponge layer, or as a
"source" anywhere in the domain.

\noindent
For a tracer ($T$) at every grid point the tendency is modified so that:
\[
\frac{dT}{dt}=\frac{dT}{dt} - \frac{M_{rbc}}{\tau_T} (T-T_{rbc})
\]

\noindent
where $M_{rbc}$ is a 3-D mask (no time dependence) with
values between 0 and 1. Where $M_{rbc}$ is 1, relaxing timescale
is $1/\tau_T$. Where it is 0 there is no relaxing.
The value relaxed to is a 3-D (potentially varying in
time) field given by $T_{rbc}$. 

A seperate mask can be used for T,S and ptracers and
each of these
can be relaxed or not and can have its own timescale
$\tau_T$. These are set in data.rbcs (see below).

\subsubsection {Key subroutines and parameters}

The only change need in the code might be in {RBCS.H}, for
PARAMETER(maskLEN = 3 ), if you need more than 3
masks (see below).

\vspace{.5cm}

\noindent
There are runtime parameters
set in {\it data.rbcs}:\\
These runtime options include\\
Set in {RBCS\_PARM01}:\\
$\bullet$ Parameters to set the timing for periodic fields to
relax to are to
be loaded are: {\it rbcs\_ForcingPeriod}, {\it rbcs\_ForcingCycle}.
The former is how often to load, the latter is how often to cycle
through those fields (eg. period couple be monthly and cycle one year).
rbcs\_ForcingCycle=0 meaning no periodic forcing, and the relax field
is only read in at the beginning of the run and kept constant
the rest of the run. Default is 0.
\\
$\bullet$  {\bf rbcsIniter}: if you want to offset rbcs forcing
timing. Default is nIter0.\\
$\bullet$  {\bf useRBCtemp}: true or false (default false)\\
$\bullet$  {\bf useRBCsalt}: true or false (default false)\\
$\bullet$  {\bf useRBCptracers}: true or false (default false), must be using
ptracers to set true\\
$\bullet$  {\bf tauRelaxT}: timescale in seconds of relaxing
in temperature ($\tau_T$ in equation above). 
Where mask is 1, relax rate will be
1/tauRelaxT. Default is 1.
$\bullet$  {\bf tauRelaxS}: same for salinity.
$\bullet$  {\bf relaxMaskFile(irbc)}: filename of 3-D file
with mask ($M_{rbc}$ in equation above. 
Need a file for each irbc. 1=temperature,
2=salinity, 3=ptracer01, 4=ptracer02 etc. If the mask numbers
end (see maskLEN) are less than the number tracers, then
relaxMaskFile(maskLEN) is used for all remaining ptracers.\\
$\bullet$  {\bf relaxTFile}: name of file where temperatures
that need to be realxed to ($T_{rbc}$ in equation above)
are stored. Need 3-D fields to
match model domain, and as many entries as given by
rbcsForcingPeriod and rbcsForcingCycle.\\
$\bullet$  {\bf relaxSFile}: same for salinity.\\

\vspace{.5cm}
\noindent
Set in {RBCS\_PARM02} for each of the ptracers (iTrc):\\
$\bullet$ {\bf useRBCptrnum(iTrc)}: true or false (default
is false).\\
$\bullet$ {\bf tauRelaxPTR(iTrc)}: relax timescale.\\
$\bullet$ {\bf relaxPtracerFile(iTrc)}: file with relax
fields.\\


\subsubsection{Do's and Don'ts}

\subsubsection{Reference Material}

\subsubsection{Experiments and tutorials that use rbcs}
\label{sec:pkg:rbcs:experiments}


%%% \end{itemize}

1	stephd	1.1	\subsection {RBCS Package}
2			\label{sec:pkg:rbcs}
3			\begin{rawhtml}
4			<!-- CMIREDIR:package_rbcs: -->
5			\end{rawhtml}
6
7			\subsubsection {Introduction}
8
9			A package which provides the flexibility
10			to relax fields (temperature, salinity, ptracers)
11			in any 3-D location:
12			so could be used as a sponge layer, or as a
13			"source" anywhere in the domain.
14
15			\noindent
16			For a tracer ($T$) at every grid point the tendency is modified so that:
17			\[
18			\frac{dT}{dt}=\frac{dT}{dt} - \frac{M_{rbc}}{\tau_T} (T-T_{rbc})
19			\]
20
21			\noindent
22			where $M_{rbc}$ is a 3-D mask (no time dependence) with
23			values between 0 and 1. Where $M_{rbc}$ is 1, relaxing timescale
24			is $1/\tau_T$. Where it is 0 there is no relaxing.
25			The value relaxed to is a 3-D (potentially varying in
26			time) field given by $T_{rbc}$.
27
28			A seperate mask can be used for T,S and ptracers and
29			each of these
30			can be relaxed or not and can have its own timescale
31			$\tau_T$. These are set in data.rbcs (see below).
32
33			\subsubsection {Key subroutines and parameters}
34
35			The only change need in the code might be in {RBCS.H}, for
36			PARAMETER(maskLEN = 3 ), if you need more than 3
37			masks (see below).
38
39			\vspace{.5cm}
40
41			\noindent
42			There are runtime parameters
43			set in {\it data.rbcs}:\\
44			These runtime options include\\
45			Set in {RBCS\_PARM01}:\\
46			$\bullet$ Parameters to set the timing for periodic fields to
47			relax to are to
48			be loaded are: {\it rbcs\_ForcingPeriod}, {\it rbcs\_ForcingCycle}.
49			The former is how often to load, the latter is how often to cycle
50			through those fields (eg. period couple be monthly and cycle one year).
51			rbcs\_ForcingCycle=0 meaning no periodic forcing, and the relax field
52			is only read in at the beginning of the run and kept constant
53			the rest of the run. Default is 0.
54			\\
55			$\bullet$ {\bf rbcsIniter}: if you want to offset rbcs forcing
56			timing. Default is nIter0.\\
57			$\bullet$ {\bf useRBCtemp}: true or false (default false)\\
58			$\bullet$ {\bf useRBCsalt}: true or false (default false)\\
59			$\bullet$ {\bf useRBCptracers}: true or false (default false), must be using
60			ptracers to set true\\
61			$\bullet$ {\bf tauRelaxT}: timescale in seconds of relaxing
62			in temperature ($\tau_T$ in equation above).
63			Where mask is 1, relax rate will be
64			1/tauRelaxT. Default is 1.
65			$\bullet$ {\bf tauRelaxS}: same for salinity.
66			$\bullet$ {\bf relaxMaskFile(irbc)}: filename of 3-D file
67			with mask ($M_{rbc}$ in equation above.
68			Need a file for each irbc. 1=temperature,
69			2=salinity, 3=ptracer01, 4=ptracer02 etc. If the mask numbers
70			end (see maskLEN) are less than the number tracers, then
71			relaxMaskFile(maskLEN) is used for all remaining ptracers.\\
72			$\bullet$ {\bf relaxTFile}: name of file where temperatures
73			that need to be realxed to ($T_{rbc}$ in equation above)
74			are stored. Need 3-D fields to
75			match model domain, and as many entries as given by
76			rbcsForcingPeriod and rbcsForcingCycle.\\
77			$\bullet$ {\bf relaxSFile}: same for salinity.\\
78
79			\vspace{.5cm}
80			\noindent
81			Set in {RBCS\_PARM02} for each of the ptracers (iTrc):\\
82			$\bullet$ {\bf useRBCptrnum(iTrc)}: true or false (default
83			is false).\\
84			$\bullet$ {\bf tauRelaxPTR(iTrc)}: relax timescale.\\
85			$\bullet$ {\bf relaxPtracerFile(iTrc)}: file with relax
86			fields.\\
87
88
89			\subsubsection{Do's and Don'ts}
90
91			\subsubsection{Reference Material}
92
93			\subsubsection{Experiments and tutorials that use rbcs}
94			\label{sec:pkg:rbcs:experiments}
95
96
97
98	cnh	1.2	%%% \end{itemize}
99	stephd	1.1