System.out.println("original bbox= " + gcs.getBoundingBox());
LatLonRect bbox = new LatLonRect(new LatLonPointImpl(40.0, -100.0), 10.0, 20.0);
LatLonProjection llproj = new LatLonProjection();
ucar.unidata.geoloc.ProjectionRect[] prect = llproj.latLonToProjRect(bbox);
System.out.println("\n constrain bbox= " + prect[0]);
GeoGrid grid_section = grid.subset(null, null, bbox, 1, 2, 3);
GridCoordSystem gcs2 = grid_section.getCoordinateSystem();
assert null != gcs2;