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% |
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% [ST] = A_compute_potential_density(SNAPSHOT) |
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% |
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% For a time snapshot, this program computes the |
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% 3D potential density from potential temperature and salinity. |
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% THETA and SALTanom are supposed to be defined on the same |
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% domain and grid. |
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% SALTanom is by default a salinity anomaly vs 35. |
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% If not, (is absolute value) set the global variable is_SALTanom to 0 |
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% |
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% Files names are: |
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% INPUT: |
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% ./netcdf-files/<SNAPSHOT>/<netcdf_THETA>.<netcdf_domain>.<netcdf_suff> |
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% ./netcdf-files/<SNAPSHOT>/<netcdf_SALTanom>.<netcdf_domain>.<netcdf_suff> |
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% OUPUT: |
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% ./netcdf-files/<SNAPSHOT>/SIGMATHETA.<netcdf_domain>.<netcdf_suff> |
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% |
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% 06/07/2006 |
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% gmaze@mit.edu |
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% |
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|
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|
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function varargout = A_compute_potential_density(snapshot) |
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|
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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%% Setup |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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global sla netcdf_THETA netcdf_SALTanom netcdf_domain netcdf_suff |
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pv_checkpath |
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|
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|
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%% THETA and SALTanom files name: |
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filTHETA = strcat(netcdf_THETA ,'.',netcdf_domain); |
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filSALTa = strcat(netcdf_SALTanom,'.',netcdf_domain); |
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|
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%% Path and extension to find them: |
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pathname = strcat('netcdf-files',sla,snapshot); |
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ext = strcat('.',netcdf_suff); |
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|
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%% Load netcdf files: |
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ferfile = strcat(pathname,sla,filTHETA,ext); |
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ncTHETA = netcdf(ferfile,'nowrite'); |
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THETAvariables = var(ncTHETA); |
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|
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ferfile = strcat(pathname,sla,filSALTa,ext); |
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ncSALTa = netcdf(ferfile,'nowrite'); |
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SALTavariables = var(ncSALTa); |
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|
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global is_SALTanom |
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if exist('is_SALTanom') |
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if is_SALTanom == 1 |
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bS = 35; |
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else |
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bS = 0; |
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end |
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end |
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|
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%% Gridding: |
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% Don't care about the grid here ! |
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% SALTanom and THETA are normaly defined on the same grid |
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% So we compute sigma_theta on it. |
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|
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%% Flags: |
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global toshow % Turn to 1 to follow the computing process |
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|
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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%% Now we compute potential density |
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%% The routine used is densjmd95.m |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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|
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% Axis (usual netcdf files): |
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if toshow,disp('Dim');end |
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[lon lat dpt] = coordfromnc(ncTHETA); |
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nx = length(lon); |
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ny = length(lat); |
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nz = length(dpt); |
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|
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% Pre-allocate: |
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if toshow,disp('Pre-allocate');end |
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SIGMATHETA = zeros(nz,ny,nx); |
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|
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% Then compute potential density SIGMATHETA: |
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for iz = 1 : nz |
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if toshow,disp(strcat('Compute potential density at level:',num2str(iz),'/',num2str(nz)));end |
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|
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S = SALTavariables{4}(iz,:,:) + bS; % Evantualy move the anom to an absolute field |
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T = THETAvariables{4}(iz,:,:); |
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SIGMATHETA(iz,:,:) = densjmd95(S,T,zeros(ny,nx)) - 1000; |
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|
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% Eventualy make a plot of the field: |
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if 0 & iz==1 |
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clf;pcolor(squeeze(SIGMATHETA(iz,:,:))); |
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shading interp;caxis([20 30]);colorbar |
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drawnow |
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%M(iz)=getframe; % To make a video |
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end %if1 |
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end %for iz |
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|
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|
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|
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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%% Record output: |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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|
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% General informations: |
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netfil = strcat('SIGMATHETA','.',netcdf_domain,'.',netcdf_suff); |
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units = 'kg/m^3-1000'; |
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ncid = 'ST'; |
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longname = 'Potential Density'; |
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uniquename = 'potential_density'; |
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|
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% Open output file: |
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nc = netcdf(strcat(pathname,sla,netfil),'clobber'); |
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|
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% Define axis: |
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nc('X') = nx; |
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nc('Y') = ny; |
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nc('Z') = nz; |
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|
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nc{'X'} = 'X'; |
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nc{'Y'} = 'Y'; |
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nc{'Z'} = 'Z'; |
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|
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nc{'X'} = ncfloat('X'); |
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nc{'X'}.uniquename = ncchar('X'); |
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nc{'X'}.long_name = ncchar('longitude'); |
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nc{'X'}.gridtype = nclong(0); |
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nc{'X'}.units = ncchar('degrees_east'); |
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nc{'X'}(:) = lon; |
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|
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nc{'Y'} = ncfloat('Y'); |
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nc{'Y'}.uniquename = ncchar('Y'); |
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nc{'Y'}.long_name = ncchar('latitude'); |
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nc{'Y'}.gridtype = nclong(0); |
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nc{'Y'}.units = ncchar('degrees_north'); |
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nc{'Y'}(:) = lat; |
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|
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nc{'Z'} = ncfloat('Z'); |
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nc{'Z'}.uniquename = ncchar('Z'); |
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nc{'Z'}.long_name = ncchar('depth'); |
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nc{'Z'}.gridtype = nclong(0); |
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nc{'Z'}.units = ncchar('m'); |
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nc{'Z'}(:) = dpt; |
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|
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% And main field: |
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nc{ncid} = ncfloat('Z', 'Y', 'X'); |
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nc{ncid}.units = ncchar(units); |
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nc{ncid}.missing_value = ncfloat(NaN); |
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nc{ncid}.FillValue_ = ncfloat(NaN); |
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nc{ncid}.longname = ncchar(longname); |
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nc{ncid}.uniquename = ncchar(uniquename); |
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nc{ncid}(:,:,:) = SIGMATHETA; |
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|
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nc=close(nc); |
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close(ncTHETA); |
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close(ncSALTa); |
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|
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% Outputs: |
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output = struct('SIGMATHETA',SIGMATHETA,'dpt',dpt,'lat',lat,'lon',lon); |
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switch nargout |
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case 1 |
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varargout(1) = {output}; |
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end |
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