MATLAB: Time axis in netcdf files

netcdf

Hello,
I am trying to build a netcdf file from an array but I have some problems in assigning the time scale.
This array (lon, lat, sea level pressure) was obtained by averaging monthly values from the original dataset, provided as a netcdf file.
Now, I need to create a new netcdf file with this annual values but I do not know how to assign the temporal information to my array.
Here there is the code I used:
     clear all
%Open the monthly values netcdf file
ncid = netcdf.open('slp20c.nc','NC_NOWRITE');
[n0, x0, vD0, varAtt0] = netcdf.inqVar(ncid,0);
[n1, x1, vD1, varAtt1] = netcdf.inqVar(ncid,1);
[n2, x2, vD2, varAtt2] = netcdf.inqVar(ncid,2);
[n3, x3, vD3, varAtt3] = netcdf.inqVar(ncid,3);
varid0 = netcdf.inqVarID(ncid,'time');
varid1 = netcdf.inqVarID(ncid,'lon');
varid2 = netcdf.inqVarID(ncid,'lat');
varid3 = netcdf.inqVarID(ncid,'prmsl');
data0 = netcdf.getVar(ncid,0);
data1 = netcdf.getVar(ncid,1);
data2 = netcdf.getVar(ncid,2);
data3 = netcdf.getVar(ncid,3);
%Select data in the desired time range, Jan1871-Dec2007
data=data3(:,:,1:1644);
data=permute(data,[3 1 2]);
a=1:12:1644; b=12:12:1644;
%Compute the annual average of the field values
for i=1:length(a)  
      yearavg(i,:,:)=mean(data(a(i):b(i),:,:));
end
yearavg=permute(yearavg,[2 3 1]);
%Create new netcdf file with the values obtained in yearavg
nt=137; %nr of years
nx=51;  %nr of longitude points
ny=46;  %nr of latitude points
lon=310:2:410; lon=lon.';
lat=90:-2:0;   lat=lat.';
time=[1871 1 1 0 0 0];
time=repmat(time,137,1);
year=1871:2007; year=year.';
time(:,1)=year;
time=datenum(time);
filenc='test.nc';
ncid = netcdf.create(filenc,'CLASSIC_MODEL');
dimid_lon  = netcdf.defDim(ncid,'lon',nx);
dimid_lat  = netcdf.defDim(ncid,'lat',ny);
dimid_time = netcdf.defDim(ncid,'time',nt);
varid_lon  = netcdf.defVar(ncid,'lon','double',dimid_lon);
netcdf.putAtt(ncid,varid_lon,'long_name','Longitude')
netcdf.putAtt(ncid,varid_lon,'units','degree_e')
varid_lat  = netcdf.defVar(ncid,'lat','double',dimid_lat);
netcdf.putAtt(ncid,varid_lat,'long_name','Latitude')
netcdf.putAtt(ncid,varid_lat,'units','degree_n')
varid_time = netcdf.defVar(ncid,'time','double',dimid_time);
netcdf.putAtt(ncid,varid_time,'long_name','Time')
netcdf.putAtt(ncid,varid_time,'units','month')
varid_slp  = netcdf.defVar(ncid,'slp','double',[dimid_lon,dimid_lat,dimid_time]);
netcdf.putAtt(ncid,varid_slp,'long_name','slp')
netcdf.putAtt(ncid,varid_slp,'units','hPa')
netcdf.putAtt(ncid,varid_slp,'missing_value',-9999)
count=[nx ny nt];
start=[0 0 0];
netcdf.endDef(ncid)
netcdf.putVar(ncid,varid_slp,start,count,yearavg);
netcdf.close(ncid)
When I then open test.nc file, and I check the data, the new array seems to be correct, but all the longitude,latitude,time axes values are now fixed to a number (9.96920996838687e+36).
May anyone help? Thank you Isabella

Best Answer

Isabella, I dont see a netcdf.putVar for varid_lon, varid_lat etc, so I guess what you are seeing is the default fill value.
Maybe you missed the netcdf.putVar calls?
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