What are these ribbons on the wing of an MD-83?
These are Ice Detection Tufts that check for ice. If they are stuck, it indicates there's a layer of ice on the wing, disturbing airflow and presenting a danger for the engines when it detaches. They are focused around the rear root side since this is most likely to be the spot with the most buildup, as remaining cold fuel below flows to this corner.

SAS had an incident with ice a few years ago in the Gottröra Accident (SAS Flight 751) that thankfully ended relatively well.