Dear all Ferreters, I have been unsuccessfully searching for a way to plot a user-defined grid box within a certain frame. I have the following data: lat1 lat2 lat3 lat4 lon1 lon2 lon3 lon4 NO2 value to fill the polygon characterized by the four coordinates (lat1, lon1, lat2, lon2 ...) Does anyone know the way to proceed? Many thanks. Matthias