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	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			% 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 !