First, the best way to easily improve efficiency in NETCDF I/O operations is to use the low level library in MATLAB. You can find documentation on that here:
Essentially, the system works as described in the attached "exampleNETCDF.m" file.
In order to read a portion of the variable, you need to
1. open the file
2. get the variable ID
3. use "netcdf.getVar" with the appropriate starting row/column and number of rows/columns
4. close the file
The syntax for "netcdf.getVar" is as such:
>> data = netcdf.getVar(ncid,varid,start,count)start = [startRow-1, startCol-1]
because MATLAB is 1-indexed and NETCDF is 0-indexed.
count = [numRows, numCols]
