title: NCO: Copying data from one netcdf file into another only for a specific area
body: <p>I have two NetCDF files with the exact same dimensions (time,lat,lon). Below is the header of one of the files.  </p>
  
  <pre><code>netcdf file1 {
  dimensions:
          lon = 360 ;
          lat = 177 ;
          time = 360 ;
  variables:
          double lon(lon) ;
                  lon:units = "degrees_east" ;
                  lon:long_name = "Longitude" ;
          double lat(lat) ;
                  lat:units = "degrees_north" ;
                  lat:long_name = "Latitude" ;
          double time(time) ;
                  time:long_name = "Time" ;
                  time:units = "months since 1989-05-01 00:00" ;
          double tmp(time, lat, lon) ;
                  tmp:_FillValue = -999000000. ;
  }
  </code></pre>
  
  <p>I would like to copy values from one file into the other, but only for a small region determined by lat1,lat2 and lon1,lon2. Both files have the same time coordinates.   </p>
  
  <p>Something like: <code>(lon1&lt;lon&lt;=lon2) &amp; (lat1&lt;lat&lt;=lat2) file1 = file2</code></p>
  
  <p>I was wondering if I could do that with NCO.</p>
  
  <p>Any help will be appreciated.  Thank</p>