It's called wind buffeting. Almost every car will do the same thing in the right circumstance. You open up a single air "intake" without giving the air anywhere to flow, it pulsates/buffets.
Try rolling down a window or two about an inch when you have the sunroof open. Should alleviate the problem.
Try rolling down a window or two about an inch when you have the sunroof open. Should alleviate the problem.
