I am also experiencing all kinds of noises from my sunroof over what seems like even minor bumps. It seems as though most of the noise is coming from movement of the sunroof within its track. It hasn't always been this bad (2000 S80 T6).
On an earlier trip to the dealer it was said to meet Volvo specifications (that's scary), although admittedly it wasn't as bad at that time. There appear to be some "pins" (for lack of a better word) that slide into fittings when the roof is lowered and "secured" in place. Is it possible these pins are worn, allowing movement over rough surfaces? At one time I also had what I considered excessive water and air noise coming in through the roof. I found where the weatherstripping comes together on the rear of the sunroof there was a gap. I took some black silicone and sealed the gap and that seemed to help. I don't think I've answered your question about the noisy sunroof, but you're not the only one with the problem. Any more insight into this would be appreciated.