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 defined with the ratio by SIGMA 
%
% A simple potential vorticity (splQ) computing is also available.
% It is defined as: splQ = f. dSIGMATHETA/dz
%
% 06/07/2006
% 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 = '200103';


% 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';

% 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:
% 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)


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 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 defined with the ratio by SIGMA
30	%
31	% A simple potential vorticity (splQ) computing is also available.
32	% It is defined as: splQ = f. dSIGMATHETA/dz
33	%
34	% 06/07/2006
35	% gmaze@mit.edu
36	%
37	clear
38
39	disp('')
40	disp('This program will compute the potential vorticity from horizontal flow,')
41	disp('potential temperature and salinity fields')
42	disp('(For a 50800700 grid this takes around 30 minutes to compute PV ...)')
43	disp('')
44
45
46	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SETUP:
47
48	% Files are looked for in subdirectory defined by: ./netcdf-files/<snapshot>/
49	% So let's define the snapshot:
50	snapshot = '200103';
51
52
53	% File's name:
54	global netcdf_UVEL netcdf_VVEL netcdf_THETA netcdf_SALTanom
55	global netcdf_suff netcdf_domain
56	netcdf_UVEL = 'UVEL';
57	netcdf_VVEL = 'VVEL';
58	netcdf_THETA = 'THETA';
59	netcdf_SALTanom = 'SALTanom';
60	netcdf_suff = 'nc';
61	netcdf_domain = 'north_atlantic';
62
63	% FLAGS:
64
65	% Turn 0/1 the following flag to determine which PV to compute:
66	wantsplPV = 0; % (turn 1 for simple PV computing)
67
68	% Turn 0/1 this flag to get online computing informations:
69	global toshow
70	toshow = 0;
71
72
73	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% COMPUTING PV:
74	% STEP 1:
75	% Output netcdf file is:
76	% ./netcdf-files/<snapshot>/SIGMATHETA.<netcdf_domain>.<netcdf_suff>
77	A_compute_potential_density(snapshot)
78
79
80	% STEP 2:
81	% Output netcdf files are:
82	% ./netcdf-files/<snapshot>/OMEGAX.<netcdf_domain>.<netcdf_suff>
83	% ./netcdf-files/<snapshot>/OMEGAY.<netcdf_domain>.<netcdf_suff>
84	% ./netcdf-files/<snapshot>/ZETA.<netcdf_domain>.<netcdf_suff>
85	% No interest for the a splPV computing
86	if ~wantsplPV
87	B_compute_relative_vorticity(snapshot)
88	end %if
89
90	% STEP 3:
91	% Output netcdf file is:
92	% ./netcdf-files/<snapshot>/PV.<netcdf_domain>.<netcdf_suff>
93	C_compute_potential_vorticity(snapshot,wantsplPV)
94
95
96	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% THAT'S IT !