How to define two dimension longitude, latitude and variable for saving data in netcdf format?

Hello everyone,

I have longitude,laltitude and var data. All are in two dimension. All the provided examples in matlab community are focused on saving 1D latitude,longitude for 2d variable. I have tried below codes so far..

lon=rand(406,271); lat=rand(406,271); var=rand(406,271);

ncid = netcdf.create('Output.nc','NETCDF4');
dim_lon = netcdf.defDim(ncid,'lon',length(lon));
dim_lat = netcdf.defDim(ncid,'lat',length(lat));

var1_lon = netcdf.defVar(ncid,'lon','double',dim_lon);
var1_lat = netcdf.defVar(ncid,'lat','double',dim_lat);

var_50 = netcdf.defVar(ncid,'var','float', [dim_lat dim_lon]);

netcdf.putAtt(ncid,var1_lon,lon);
netcdf.putAtt(ncid,var1_lat,lat);

netcdf.putAtt(ncid,var_50,var);

I think the above code is suitable for 1D lat-lon dimension saving in netcdf. I find it difficult (showing error) to use it for 2D lat-lon data.

Looking forward to any sort of help or directions. Thanks in advance.

Answer 1

[CHIRANJIT DAS]

dimidlon = netcdf.defDim(ncid,'lon',size(lon,1));
dimidlat = netcdf.defDim(ncid,'lat',size(lon,2));

%variables 
tim_ID=netcdf.defVar(ncid,'time','double',dimidtim);
lon_ID=netcdf.defVar(ncid,'lon','double',[dimidlon,dimidlat]);
lat_ID=netcdf.defVar(ncid,'lat','double',[dimidlon dimidlat]);

Try it, this should probably work in your problem scenario.

Good luck

[ANIE]

Thanks a lot @CHIRANJIT DAS

Answer 2

[KSSV]

lon=rand(406,271); lat=rand(406,271); var=rand(406,271);

[nx,ny] = size(lon) ; 
% nc filename to be written
file = 'myfile.nc' ;

nccreate(file,'x','Dimensions',{'x',1,nx},'DeflateLevel',7) ;
nccreate(file,'y','Dimensions',{'y',1,ny},'DeflateLevel',7) ;

nccreate(file,'lon','Dimensions',{'x','y'},'DeflateLevel',7) ;
ncwrite(file,'lon',lon) ; 

nccreate(file,'lat','Dimensions',{'x','y'},'DeflateLevel',7) ;
ncwrite(file,'lat',lat) ; 

nccreate(file,'var','Dimensions',{'x','y'},'DeflateLevel',7) ;
ncwrite(file,'var',var) ;   

[ANIE]

@KSSV thanks for your response. We can do this way but it's not compatible in CDO or ncview tools.

Therefore, we are looking for any command that we can put "netcdf.defDim" itself for 2D latitude and longitude.

Looking forward to any response in this regard.

[KSSV]

You can extend the same logic.

[ANIE]

I am new to matlab. I have tried but didn't succed, would greatly appreciate your help if you could suggest how to implement it using defDim.

[KSSV]

Your lat and lon ot scattered data or a structured data?

[ANIE]

yes it is structured but changing 2D ways..

[KSSV]

Then you can just write a vector of lon and lat right? Why you want to write a 2D matrix?