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function ncep2global_ocean |
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% function ncep2global_ocean |
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|
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% read various fluxes, adds them up to have net heat flux and net |
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% freshwater flux (E-P only) |
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% interpolates the fluxes onto 90x40 grid of global_ocean.90x40x15 |
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% |
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% $Header: $ |
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% $Name: $ |
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|
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% constants |
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ql_evap = 2.5e6; % latent heat due to evaporation |
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rho_fresh = 1000; % density of fresh water |
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onemonth = 60*60*24*30; |
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% grid parameter |
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grd = mit_loadgrid(DIRECTORY WHERE THE GRID INFORMATION IS HELD ... |
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(XC*, YC*, HFAC* etc.)); |
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lonc = grd.lonc; |
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latc = grd.latc; |
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cmask = grd.cmask; % 1=wet point, NaN = dry point |
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rac = grd.rac; |
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|
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bdir = DIRECTORY WHERE THE NCEP DATA FILES ARE STORED; |
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% taux |
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ncload(fullfile(bdir,'ncep_taux_monthly.cdf'),'taux','X','Y','T') |
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% tauy |
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ncload(fullfile(bdir,'ncep_tauy_monthly.cdf'),'tauy') |
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% there appears to be a different east west convention in the data |
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taux = - taux; |
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tauy = - tauy; |
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|
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% qnet |
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ncload(fullfile(bdir,'ncep_netsolar_monthly.cdf'),'solr') |
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ncload(fullfile(bdir,'ncep_netlw_monthly.cdf'),'lwflx') % long wave radiation |
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ncload(fullfile(bdir,'ncep_latent_monthly.cdf'),'heat_flux'); |
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lhflx = heat_flux; |
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ncload(fullfile(bdir,'ncep_sensible_monthly.cdf'),'heat_flux'); |
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shflx = heat_flux; |
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|
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% emp |
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ncload(fullfile(bdir,'ncep_precip_monthly.cdf'),'prate') |
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ncload(fullfile(bdir,'ncep_runoff_monthly.cdf'),'runoff') |
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evap = lhflx/ql_evap/rho_fresh; % evaporation rate estimated from latent |
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% heat flux |
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precip = prate/rho_fresh; % change the units |
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|
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% add the fields |
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% net heat flux: sum of solar radiation, long wave flux, latent heat flux, |
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% and sensible heat flux |
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qnet = solr + lwflx + lhflx + shflx; |
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% net fresh water flux: difference between evaporation and precipitation |
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emp = evap - precip; |
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% substract the runoff (doesn't lead anywhere, unfortunately) |
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empmr = emp - change(runoff,'==',NaN,0)/rho_fresh/onemonth; |
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runoff(find(isnan(runoff)))=0; |
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empmr = emp - runoff/rho_fresh/onemonth; |
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|
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% interpolate the three fields onto 90x40 grid |
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ir = interp2global(X,Y,lonc,latc); % this sets up the |
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% interpolator ir! |
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for k = 1:length(T); |
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tauxg(:,:,k) = interp2global(X,Y,squeeze(taux(k,:,:)),lonc,latc,ir); |
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tauyg(:,:,k) = interp2global(X,Y,squeeze(tauy(k,:,:)),lonc,latc,ir); |
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qnetg(:,:,k) = interp2global(X,Y,squeeze(qnet(k,:,:)),lonc,latc,ir); |
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empg(:,:,k) = interp2global(X,Y,squeeze(emp(k,:,:)),lonc,latc,ir); |
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empmrg(:,:,k) = interp2global(X,Y,squeeze(empmr(k,:,:)),lonc,latc,ir); |
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end |
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|
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% apply landmask |
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for k = 1:length(T); |
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tauxg(:,:,k) = tauxg(:,:,k).*cmask(:,:,1); |
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tauyg(:,:,k) = tauyg(:,:,k).*cmask(:,:,1); |
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qnetg(:,:,k) = qnetg(:,:,k).*cmask(:,:,1); |
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empg(:,:,k) = empg(:,:,k).*cmask(:,:,1); |
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empmrg(:,:,k) = empmrg(:,:,k).*cmask(:,:,1); |
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end |
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% balance the fluxes |
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effrac = rac.*cmask(:,:,1); |
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mqnet = mit_mean(qnetg,effrac); |
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qnetb = qnetg-mean(mqnet); |
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|
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memp = mit_mean(empg,effrac); |
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empb = empg-mean(memp); |
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mempmr = mit_mean(empmrg,effrac); |
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empmrb = empmrg-mean(mempmr); |
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|
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% apply the landmasks one more time (because we have added something |
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% to what should have been zero == land) |
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for k = 1:length(T); |
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qnetb(:,:,k) = qnetb(:,:,k).*smask; |
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empb(:,:,k) = empb(:,:,k).*smask; |
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empmrb(:,:,k) = empmrb(:,:,k).*smask; |
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end |
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|
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% save the fields |
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acc = 'real*4'; |
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mit_writefield('ncep_taux.bin',change(tauxg,'==',NaN,0),acc); |
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mit_writefield('ncep_tauy.bin',change(tauyg,'==',NaN,0),acc); |
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mit_writefield('ncep_qnet.bin',change(qnetb,'==',NaN,0),acc); |
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mit_writefield('ncep_emp.bin',change(empb,'==',NaN,0),acc); |
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mit_writefield('ncep_empmr.bin',change(empmrb,'==',NaN,0),acc); |
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|
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return |
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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|
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function Y = mit_mean(X,area); |
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%function Y = mit_mean(X,area); |
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|
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na = ndims(area); |
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n = ndims(X); |
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full_area = nansum(area(:)); |
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if n == 2 & na == 2 |
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[nx ny] = size(X); |
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Xa = X.*area; |
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Y = nansum(Xa(:))/full_area; |
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elseif n == 3 & na == 2 |
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[nx ny nt] = size(X); |
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Xa = X.*repmat(area,[1 1 nt]); |
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for k=1:nt |
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Y(k) = nansum(nansum(Xa(:,:,k)))/full_area; |
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end |
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elseif n == 3 & na == 3 |
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[nx ny nz] = size(X); |
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Xa = X.*area; |
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Y = nansum(Xa(:))/full_area; |
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else |
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error('X and area have to have consistent dimensions') |
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end |
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|
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return |
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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|
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function count = mit_writefield(fname,h,accuracy) |
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%function count = mit_writefield(fname,h,accuracy) |
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|
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ieee='ieee-be'; |
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|
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[fid message] = fopen(fname,'w',ieee); |
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if fid <= 0 |
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error([message ', filename: ', [fname]]) |
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end |
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|
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clear count |
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dims = size(h); |
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if length(dims) == 2 |
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count = fwrite(fid,h,accuracy); |
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elseif length(dims) == 3 |
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for k=1:dims(3); |
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count(k) = fwrite(fid,squeeze(h(:,:,k)),accuracy); |
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end |
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elseif length(dims) == 4 |
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for kt=1:dims(4) |
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for k=1:dims(3) |
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count(k,kt) = fwrite(fid,squeeze(h(:,:,k,kt)),accuracy); |
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end |
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end |
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end |
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|
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fclose(fid); |
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|
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return |
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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|
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function [zi] = interp2global(varargin); |
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%function [zi] = interp2global(x,y,z,xi,yi,ir); |
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|
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if nargin == 4 |
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[xx yy] = meshgrid(varargin{1},varargin{2}); |
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xx = reshape(xx,prod(size(xx)),1); |
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yy = reshape(yy,prod(size(yy)),1); |
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[xxi yyi] = meshgrid(varargin{3},varargin{4}); |
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xxv = reshape(xxi,prod(size(xxi)),1); |
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yyv = reshape(yyi,prod(size(yyi)),1); |
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% create map |
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if ~exist('ir','var'); |
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r = 230e3; %m |
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for k = 1:length(xxv); |
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% find all points within radius r |
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radius = lonlat2dist(xxv(k),yyv(k),xx,yy); |
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ir{k} = find(radius<=r); |
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end |
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end |
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zi = ir; |
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else |
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% zi = interp2_global(x,y,z,ix,iy','spline')'; |
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z = varargin{3}; |
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xi = varargin{4}; |
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yi = varargin{5}; |
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[xxi yyi] = meshgrid(varargin{4},varargin{5}); |
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ir = varargin{6}; |
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zzv = repmat(NaN,length(ir),1); |
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% interpolate |
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for k = 1:length(ir); |
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% find all points within radius r |
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zzv(k) = mean(z(ir{k})); |
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end |
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zi = reshape(zzv,size(xxi))'; |
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end |
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|
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return |
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|
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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|
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function r = lonlat2dist(lon,lat,lons,lats) |
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%function r = lonlat2dist(lon,lat,lons,lats) |
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% |
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% returns distance (in meters) between postion (lon,lat) and positions |
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% (lons,lats) on the earth (sphere). length(r) = length(lons) |
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|
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earth=6371000; |
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deg2rad=pi/180; |
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nx=length(lon); |
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lt = deg2rad*lat; |
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ln = deg2rad*lon; |
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lts = deg2rad*lats; |
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lns = deg2rad*lons; |
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alpha = ... |
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acos( ( cos(lt)*cos(lts) ).*cos(ln-lns) ... |
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+ ( sin(lt)*sin(lts) ) ); |
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r = earth*abs(alpha'); |
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|
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return |
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