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gmaze |
1.1 |
% |
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gmaze |
1.2 |
% [QEk] = compute_QEk(SNAPSHOT) |
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gmaze |
1.1 |
% |
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% Here we compute the lateral heat flux induced by Ekman currents |
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% from JFz, the PV flux induced by frictional forces: |
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% QEk = - Cw * EKL * JFz / alpha / f |
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% where: |
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% Cw = 4187 J/kg/K is the specific heat of seawater |
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% EKL is the Ekman layer depth (m) |
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% JFz is the PV flux (kg/m3/s2) |
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% alpha = 2.5*E-4 1/K is the thermal expansion coefficient |
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% f = 2*OMEGA*sin(LAT) is the Coriolis parameter |
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% |
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% This allows a direct comparison with the net surface heat flux Qnet |
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% which forces the surface Pv flux due to diabatic processes. |
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% |
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% Remind that: |
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% JFz = ( TAUx * dSIGMATHETA/dy - TAUy * dSIGMATHETA/dx ) / RHO / EKL |
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% |
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% Files names are: |
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% INPUT: |
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% ./netcdf-files/<SNAPSHOT>/<netcdf_JFz>.<netcdf_domain>.<netcdf_suff> |
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% ./netcdf-files/<SNAPSHOT>/<netcdf_EKL>.<netcdf_domain>.<netcdf_suff> |
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% OUPUT: |
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% ./netcdf-files/<SNAPSHOT>/QEk.<netcdf_domain>.<netcdf_suff> |
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% |
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% with netcdf_* as global variables |
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% |
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% 06/27/06 |
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% gmaze@mit.edu |
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gmaze |
1.2 |
function varargout = compute_QEk(snapshot) |
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gmaze |
1.1 |
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global sla toshow |
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global netcdf_suff netcdf_domain |
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global netcdf_JFz netcdf_EKL |
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pv_checkpath |
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% NETCDF file name: |
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filJFz = netcdf_JFz; |
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filEKL = netcdf_EKL; |
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% Path and extension to find them: |
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pathname = strcat('netcdf-files',sla); |
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ext = netcdf_suff; |
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% Load files: |
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ferfile = strcat(pathname,sla,snapshot,sla,filJFz,'.',netcdf_domain,'.',ext); |
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ncJFz = netcdf(ferfile,'nowrite'); |
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JFz = ncJFz{4}(1,:,:); |
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[JFzlon JFzlat JFzdpt] = coordfromnc(ncJFz); |
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ferfile = strcat(pathname,sla,snapshot,sla,filEKL,'.',netcdf_domain,'.',ext); |
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ncEKL = netcdf(ferfile,'nowrite'); |
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EKL = ncEKL{4}(1,:,:); |
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[EKLlon EKLlat EKLdpt] = coordfromnc(ncEKL); |
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% Make them having same limits: |
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% (JFz is defined with first/last points removed from the EKL grid) |
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nx = length(JFzlon) ; |
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ny = length(JFzlat) ; |
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nz = length(JFzdpt) ; |
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EKL = squeeze(EKL(2:ny+1,2:nx+1)); |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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% |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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% Dim: |
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if toshow, disp('dim'), end |
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nx = length(JFzlon) ; |
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ny = length(JFzlat) ; |
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nz = length(JFzdpt) ; |
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% Pre-allocate: |
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if toshow, disp('pre-allocate'), end |
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QEk = zeros(nz,ny,nx).*NaN; |
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% Planetary vorticity: |
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f = 2*(2*pi/86400)*sin(JFzlat*pi/180); |
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[a f]=meshgrid(JFzlon,f); clear a c |
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% Coefficient: |
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Cw = 4187; |
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al = 2.5*10^(-4); % Average surface value of alpha |
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coef = - Cw / al; |
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% Compute flux: |
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QEk = coef.* EKL .* JFz ./ f; |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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% Record |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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if toshow, disp('record'), end |
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% General informations: |
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netfil = 'QEk'; |
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units = 'W/m2'; |
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ncid = 'QEk'; |
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longname = 'Lateral heat flux induced by Ekman currents'; |
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uniquename = 'QEk'; |
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% Open output file: |
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nc = netcdf(strcat(pathname,sla,snapshot,sla,netfil,'.',netcdf_domain,'.',ext),'clobber'); |
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% Define axis: |
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nx = length(JFzlon) ; |
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ny = length(JFzlat) ; |
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nz = 1 ; |
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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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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'}(:) = JFzlon; |
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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'}(:) = JFzlat; |
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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'}(:) = JFzdpt(1); |
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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}(:,:,:) = QEk; |
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nc=close(nc); |
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gmaze |
1.2 |
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% Output: |
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output = struct('QEk',QEk,'lat',JFzlat,'lon',JFzlon); |
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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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