Stuart Manning has studied some hundred tree samples from the Agean and dates the eruption to 1660-1613.
The olive tree researchers date the eruption to 1630-1600.
Very old trees from Ireland and California point to a succession of extremely cold and wet summers in the 1620s.
Claus Hammer (Denmark) has studied the Greenland ice core (you can count the years fairly exactly there) and has found signs of a very big eruption in 1644 BC.

Wolfgang