--- MITgcm_contrib/gmaze_pv/main_getPV.m	2006/06/16 21:12:20	1.1
+++ MITgcm_contrib/gmaze_pv/main_getPV.m	2006/06/22 18:13:30	1.2
@@ -26,12 +26,19 @@
 % 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 
+% 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
 %
-% 06/07/2006
+% 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
@@ -47,7 +54,7 @@
 
 % Files are looked for in subdirectory defined by: ./netcdf-files/<snapshot>/
 % So let's define the snapshot:
-snapshot = '200103';
+snapshot = '';
 
 
 % File's name:
@@ -58,19 +65,24 @@
 netcdf_THETA    = 'THETA';
 netcdf_SALTanom = 'SALTanom';
 netcdf_suff     = 'nc';
-netcdf_domain   = 'north_atlantic';
+netcdf_domain   = 'north_atlantic'; % Must not be empty !
 
-% FLAGS:
 
+% 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>
@@ -92,5 +104,13 @@
 %       ./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 !