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	\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	\end{itemize}
99