MATLAB: How to save the results of NetCDF as .nc file

nccreatencwrite

Hi all,

I have a .nc file containing lat, lon, time, and values of parameters.

After applying my conditions, i get the values of parameters in same [x y t] dimension, now i want to save my outputs as a different nc file having same lat, lon and time as it had before.

How to do it… could anyone help me?

Best Answer

You can use nccreatewrite function to create a nc file having all the required variables. Example:

lon=(65:0.5:95)';
lat=(3:0.5:35)';
data=randi(20,65,61,365);
nccreatewrite('test1.nc','lat',{'lat','c'},lat)
nccreatewrite('test1.nc','lon',{'lon','c'},lon)
nccreatewrite('test1.nc','TC',{'lat','lon','days'},data)

The files created by matlab (either from this funciton or from the basic matlab function) won't work in grads. You have to write the descriptor file for the MATLAB created nc file.

Related Solutions

MATLAB: Extracting data from .nc from a defined lat/lon area

An optimization is to use min() directly instead of find.

I think your abs() is wrong -- you could end up matching -4.8 to +5 for example.

[~, lat_index] = min(N3_4_lat - lat);
[~, lon_index] = min(N3_4_lon - lon);

Your error is on

chlor_N3_4(i) = chlor(lon_index,lat_index);

You have assumed here that lon_index is the first index. You need to check that assumption: netcdf arrays are transposed compared to what you would expect in MATLAB.

MATLAB: Trouble loading data from .nc file

What version of Matlab are you running? They've introduced some nice higher-level reading and writing functions in more recent versions (R2010 and above, I think). You should be able to get the data quickly via ncread. Based on the file details:

ncdisp(url, '/', 'min')
 Source:
           http://www.esrl.noaa.gov/psd/thredds/dodsC/Datasets/ncep.reanalysis/pressure/hgt.1968.nc
Format:
           64bit
Variables:
    level
           Size:       17x1
           Dimensions: level
           Datatype:   single
    lat  
           Size:       73x1
           Dimensions: lat
           Datatype:   single
    lon  
           Size:       144x1
           Dimensions: lon
           Datatype:   single
    time 
           Size:       1464x1
           Dimensions: time
           Datatype:   double
    hgt  
           Size:       144x73x17x1464
           Dimensions: lon,lat,level,time
           Datatype:   int16

you might not want to read in that whole variable all at once (b/c it has a scale factor and offset, it will be read in as a double array). To get one slice at time 1 and level 1:

x = ncread(url, 'hgt', [1 1 1 1], [Inf Inf 1 1]);

Best Answer

Related Solutions

MATLAB: Extracting data from .nc from a defined lat/lon area

MATLAB: Trouble loading data from .nc file

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