It can be still "Etude sur la latitude" or "Etude autour de la latitude" what means that you are making an musical exercise around the theme of latitude.
Or maybe also "variation sur la latitude" In music variations are the small variations you are doing around the main theme. So it can work. It is like if you are doing small variations around the latitude.
Can I just ask what kind music you're playing? (I guess Pierre Schaeffer is one of your reference? )