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	%
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	% Note that Q is not initialy defined with the ratio by RHO (see below).
30	%
31	% A simple potential vorticity (splQ) computing is also available.
32	% It is defined as: splQ = f. dSIGMATHETA/dz
33	%
34	% 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@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	snapshot = '';
58
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	netcdf_domain = 'north_atlantic'; % Must not be empty !
69
70
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	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	% 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	% 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
116	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% THAT'S IT !