MITgcm_contrib/gmaze_pv/main_getPV.m

% 
% THIS IS NOT A FUNCTION
%
% Here is the main program to compute the potential vorticity Q
% from the flow (UVEL,VVEL), potential temperature (THETA) and
% salinity (SALTanom); given snapshot fields.
% 3 steps to do it:
%   1- compute the potential density SIGMATHETA (also called ST)
%      from THETA and SALTanom: 
%      ST = SIGMA(S,THETA,p=0)
%   2- compute the 3D relative vorticity field OMEGA (called O)
%      without vertical velocity terms:
%      O = ( -dVdz ; dUdz ; dVdx - dUdy )
%   3- compute the potential vorticity Q:
%      Q = Ox.dSTdx + Oy.dSTdy + (f+Oz).dSTdz
%      (note that we only add the planetary vorticity at this last
%      step)
%
% Input files are supposed to be in a subdirectory called: 
% ./netcdf-files/<snapshot>/
%
% File names id are stored in global variables:
%    netcdf_UVEL, netcdf_VVEL, netcdf_THETA, netcdf_SALTanom
% with the format:
%    netcdf_<ID>.<netcdf_domain>.<netcdf_suff>
% where netcdf_domain and netcdf_suff are also in global
% THE DOT IS ADDED IN SUB-PROG, SO AVOID IT IN DEFINITIONS
%
% Note that Q is not initialy defined with the ratio by RHO (see below).
%
% A simple potential vorticity (splQ) computing is also available.
% It is defined as: splQ = f. dSIGMATHETA/dz
%
% It's also possible to add a real last step 4 to compute PV as:
% Q = -1/RHO * [Ox.dSTdx + Oy.dSTdy + (f+Oz).dSTdz]
% Note that in this case, program loads the PV output from the
% routine C_compute_potential_vorticity and simply multiply it
% by: -1/RHO.
% RHO may be computed with the routine compute_density.m
% 
% 06/21/2006
% gmaze@mit.edu
%
clear

disp('')
disp('This program will compute the potential vorticity from horizontal flow,')
disp('potential temperature and salinity fields')
disp('(For a 50*800*700 grid this takes around 30 minutes to compute PV ...)')
disp('')


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   SETUP:

% Files are looked for in subdirectory defined by: ./netcdf-files/<snapshot>/
% So let's define the snapshot:
snapshot = '';


% File's name:
global netcdf_UVEL netcdf_VVEL netcdf_THETA netcdf_SALTanom
global netcdf_suff netcdf_domain
netcdf_UVEL     = 'UVEL';
netcdf_VVEL     = 'VVEL';
netcdf_THETA    = 'THETA';
netcdf_SALTanom = 'SALTanom';
netcdf_suff     = 'nc';
netcdf_domain   = 'north_atlantic'; % Must not be empty !


% FLAGS:
% Turn 0/1 the following flag to determine which PV to compute:
wantsplPV = 0; % (turn 1 for simple PV computing)
% Turn 0/1 this flag to get online computing informations:
global toshow
toshow = 0;


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   COMPUTING PV:
if isempty('snapshot')
  disp(' THIS FILE IS AN EXAMPLE OF USE, COPY IT INTO YOUR')
  disp(' WORKING DIRECTORY WITH A DIFFERENT NAME AND')
  disp(' CUSTOMIZE IT !');
end  

% STEP 1:
% Output netcdf file is:
%       ./netcdf-files/<snapshot>/SIGMATHETA.<netcdf_domain>.<netcdf_suff>
A_compute_potential_density(snapshot)


% STEP 2:
% Output netcdf files are:
%       ./netcdf-files/<snapshot>/OMEGAX.<netcdf_domain>.<netcdf_suff>
%       ./netcdf-files/<snapshot>/OMEGAY.<netcdf_domain>.<netcdf_suff>
%       ./netcdf-files/<snapshot>/ZETA.<netcdf_domain>.<netcdf_suff>
% No interest for the a splPV computing
if ~wantsplPV
   B_compute_relative_vorticity(snapshot)
end %if

% STEP 3:
% Output netcdf file is:
%       ./netcdf-files/<snapshot>/PV.<netcdf_domain>.<netcdf_suff>
C_compute_potential_vorticity(snapshot,wantsplPV)

% STEP 4:
% Output netcdf file is (replace last one):
%       ./netcdf-files/<snapshot>/PV.<netcdf_domain>.<netcdf_suff>
global netcdf_RHO netcdf_PV
netcdf_RHO = 'RHO';
netcdf_PV  = 'PV';
D_compute_potential_vorticity(snapshot)


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% THAT'S IT !
1	gmaze	1.1	%
2			% THIS IS NOT A FUNCTION
3			%
4			% Here is the main program to compute the potential vorticity Q
5			% from the flow (UVEL,VVEL), potential temperature (THETA) and
6			% salinity (SALTanom); given snapshot fields.
7			% 3 steps to do it:
8			% 1- compute the potential density SIGMATHETA (also called ST)
9			% from THETA and SALTanom:
10			% ST = SIGMA(S,THETA,p=0)
11			% 2- compute the 3D relative vorticity field OMEGA (called O)
12			% without vertical velocity terms:
13			% O = ( -dVdz ; dUdz ; dVdx - dUdy )
14			% 3- compute the potential vorticity Q:
15			% Q = Ox.dSTdx + Oy.dSTdy + (f+Oz).dSTdz
16			% (note that we only add the planetary vorticity at this last
17			% step)
18			%
19			% Input files are supposed to be in a subdirectory called:
20			% ./netcdf-files/<snapshot>/
21			%
22			% File names id are stored in global variables:
23			% netcdf_UVEL, netcdf_VVEL, netcdf_THETA, netcdf_SALTanom
24			% with the format:
25			% netcdf_<ID>.<netcdf_domain>.<netcdf_suff>
26			% where netcdf_domain and netcdf_suff are also in global
27			% THE DOT IS ADDED IN SUB-PROG, SO AVOID IT IN DEFINITIONS
28			%
29	gmaze	1.2	% Note that Q is not initialy defined with the ratio by RHO (see below).
30	gmaze	1.1	%
31			% A simple potential vorticity (splQ) computing is also available.
32			% It is defined as: splQ = f. dSIGMATHETA/dz
33			%
34	gmaze	1.2	% It's also possible to add a real last step 4 to compute PV as:
35			% Q = -1/RHO * [Ox.dSTdx + Oy.dSTdy + (f+Oz).dSTdz]
36			% Note that in this case, program loads the PV output from the
37			% routine C_compute_potential_vorticity and simply multiply it
38			% by: -1/RHO.
39			% RHO may be computed with the routine compute_density.m
40			%
41			% 06/21/2006
42	gmaze	1.1	% gmaze@mit.edu
43			%
44			clear
45
46			disp('')
47			disp('This program will compute the potential vorticity from horizontal flow,')
48			disp('potential temperature and salinity fields')
49			disp('(For a 50800700 grid this takes around 30 minutes to compute PV ...)')
50			disp('')
51
52
53			%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SETUP:
54
55			% Files are looked for in subdirectory defined by: ./netcdf-files/<snapshot>/
56			% So let's define the snapshot:
57	gmaze	1.2	snapshot = '';
58	gmaze	1.1
59
60			% File's name:
61			global netcdf_UVEL netcdf_VVEL netcdf_THETA netcdf_SALTanom
62			global netcdf_suff netcdf_domain
63			netcdf_UVEL = 'UVEL';
64			netcdf_VVEL = 'VVEL';
65			netcdf_THETA = 'THETA';
66			netcdf_SALTanom = 'SALTanom';
67			netcdf_suff = 'nc';
68	gmaze	1.2	netcdf_domain = 'north_atlantic'; % Must not be empty !
69
70	gmaze	1.1
71			% FLAGS:
72			% Turn 0/1 the following flag to determine which PV to compute:
73			wantsplPV = 0; % (turn 1 for simple PV computing)
74			% Turn 0/1 this flag to get online computing informations:
75			global toshow
76			toshow = 0;
77
78
79			%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% COMPUTING PV:
80	gmaze	1.2	if isempty('snapshot')
81			disp(' THIS FILE IS AN EXAMPLE OF USE, COPY IT INTO YOUR')
82			disp(' WORKING DIRECTORY WITH A DIFFERENT NAME AND')
83			disp(' CUSTOMIZE IT !');
84			end
85
86	gmaze	1.1	% STEP 1:
87			% Output netcdf file is:
88			% ./netcdf-files/<snapshot>/SIGMATHETA.<netcdf_domain>.<netcdf_suff>
89			A_compute_potential_density(snapshot)
90
91
92			% STEP 2:
93			% Output netcdf files are:
94			% ./netcdf-files/<snapshot>/OMEGAX.<netcdf_domain>.<netcdf_suff>
95			% ./netcdf-files/<snapshot>/OMEGAY.<netcdf_domain>.<netcdf_suff>
96			% ./netcdf-files/<snapshot>/ZETA.<netcdf_domain>.<netcdf_suff>
97			% No interest for the a splPV computing
98			if ~wantsplPV
99			B_compute_relative_vorticity(snapshot)
100			end %if
101
102			% STEP 3:
103			% Output netcdf file is:
104			% ./netcdf-files/<snapshot>/PV.<netcdf_domain>.<netcdf_suff>
105			C_compute_potential_vorticity(snapshot,wantsplPV)
106
107	gmaze	1.2	% STEP 4:
108			% Output netcdf file is (replace last one):
109			% ./netcdf-files/<snapshot>/PV.<netcdf_domain>.<netcdf_suff>
110			global netcdf_RHO netcdf_PV
111			netcdf_RHO = 'RHO';
112			netcdf_PV = 'PV';
113			D_compute_potential_vorticity(snapshot)
114
115	gmaze	1.1
116			%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% THAT'S IT !