| 1 |
% |
| 2 |
% [ALPHA] = compute_alpha(SNAPSHOT) |
| 3 |
% |
| 4 |
% This function computes the thermal expansion coefficient from |
| 5 |
% files of potential temperature THETA and salinity anomaly |
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% SALTanom. |
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% SALTanom is by default a salinity anomaly vs 35PSU. |
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% If not, (is absolute value) set the global variable is_SALTanom to 0 |
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% |
| 10 |
% Files name 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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% OUTPUT: |
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% ./netcdf-files/<SNAPSHOT>/ALPHA.<netcdf_domain>.<netcdf_suff> |
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% |
| 17 |
% with: netcdf_* as global variables |
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% |
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% Alpha is computed with the subroutine sw_alpha from package SEAWATER |
| 20 |
% |
| 21 |
% 06/27/06 |
| 22 |
% gmaze@mit.edu |
| 23 |
|
| 24 |
function varargout = compute_alpha(snapshot) |
| 25 |
|
| 26 |
global sla toshow |
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global netcdf_suff netcdf_domain |
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global netcdf_SALTanom netcdf_THETA |
| 29 |
pv_checkpath |
| 30 |
|
| 31 |
|
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% Path and extension to find netcdf-files: |
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pathname = strcat('netcdf-files',sla); |
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ext = netcdf_suff; |
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|
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% Load files: |
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ferfile = strcat(pathname,sla,snapshot,sla,netcdf_THETA,'.',netcdf_domain,'.',ext); |
| 38 |
ncT = netcdf(ferfile,'nowrite'); |
| 39 |
[Tlon Tlat Tdpt] = coordfromnc(ncT); |
| 40 |
|
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ferfile = strcat(pathname,sla,snapshot,sla,netcdf_SALTanom,'.',netcdf_domain,'.',ext); |
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ncS = netcdf(ferfile,'nowrite'); |
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[Slon Slat Sdpt] = coordfromnc(ncS); % but normaly is the same grid as T |
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|
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% Salinity field ref; |
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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 |
| 54 |
|
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 57 |
% surface PV flux |
| 58 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 59 |
|
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% Define axis: |
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nx = length(Tlon) ; |
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ny = length(Tlat) ; |
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nz = length(Tdpt) ; |
| 64 |
|
| 65 |
|
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% Pre-allocation: |
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if toshow,disp('Pre-allocate');end |
| 68 |
ALPHA = zeros(nz,ny,nx).*NaN; |
| 69 |
|
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% Compute alpha: |
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for iz = 1 : nz |
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if toshow,disp(strcat('Compute alpha for level:',num2str(iz),'/',num2str(nz)));end |
| 73 |
TEMP = ncT{4}(iz,:,:); |
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SALT = ncS{4}(iz,:,:) + bS; |
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PRES = (0.09998*9.81*Tdpt(iz))*ones(ny,nx); |
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ALPHA(iz,:,:) = sw_alpha(SALT,TEMP,PRES,'ptmp'); |
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end %for iz |
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|
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
| 81 |
% Record |
| 82 |
%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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if toshow, disp('record'), end |
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|
| 85 |
% General informations: |
| 86 |
netfil = 'ALPHA'; |
| 87 |
units = '1/K'; |
| 88 |
ncid = 'ALPHA'; |
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longname = 'Thermal expansion coefficient'; |
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uniquename = 'ALPHA'; |
| 91 |
|
| 92 |
% Open output file: |
| 93 |
nc = netcdf(strcat(pathname,sla,snapshot,sla,netfil,'.',netcdf_domain,'.',ext),'clobber'); |
| 94 |
|
| 95 |
% Define axis: |
| 96 |
nx = length(Tlon) ; |
| 97 |
ny = length(Tlat) ; |
| 98 |
nz = length(Tdpt) ; |
| 99 |
|
| 100 |
nc('X') = nx; |
| 101 |
nc('Y') = ny; |
| 102 |
nc('Z') = nz; |
| 103 |
|
| 104 |
nc{'X'} = ncfloat('X'); |
| 105 |
nc{'X'}.uniquename = ncchar('X'); |
| 106 |
nc{'X'}.long_name = ncchar('longitude'); |
| 107 |
nc{'X'}.gridtype = nclong(0); |
| 108 |
nc{'X'}.units = ncchar('degrees_east'); |
| 109 |
nc{'X'}(:) = Tlon; |
| 110 |
|
| 111 |
nc{'Y'} = ncfloat('Y'); |
| 112 |
nc{'Y'}.uniquename = ncchar('Y'); |
| 113 |
nc{'Y'}.long_name = ncchar('latitude'); |
| 114 |
nc{'Y'}.gridtype = nclong(0); |
| 115 |
nc{'Y'}.units = ncchar('degrees_north'); |
| 116 |
nc{'Y'}(:) = Tlat; |
| 117 |
|
| 118 |
nc{'Z'} = ncfloat('Z'); |
| 119 |
nc{'Z'}.uniquename = ncchar('Z'); |
| 120 |
nc{'Z'}.long_name = ncchar('depth'); |
| 121 |
nc{'Z'}.gridtype = nclong(0); |
| 122 |
nc{'Z'}.units = ncchar('m'); |
| 123 |
nc{'Z'}(:) = Tdpt; |
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|
| 125 |
% And main field: |
| 126 |
nc{ncid} = ncfloat('Z', 'Y', 'X'); |
| 127 |
nc{ncid}.units = ncchar(units); |
| 128 |
nc{ncid}.missing_value = ncfloat(NaN); |
| 129 |
nc{ncid}.FillValue_ = ncfloat(NaN); |
| 130 |
nc{ncid}.longname = ncchar(longname); |
| 131 |
nc{ncid}.uniquename = ncchar(uniquename); |
| 132 |
nc{ncid}(:,:,:) = ALPHA; |
| 133 |
|
| 134 |
nc=close(nc); |
| 135 |
close(ncS); |
| 136 |
close(ncT); |
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|
| 138 |
% Output: |
| 139 |
output = struct('ALPHA',ALPHA,'dpt',Tdpt,'lat',Tlat,'lon',Tlon); |
| 140 |
switch nargout |
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case 1 |
| 142 |
varargout(1) = {output}; |
| 143 |
end |
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