Running time 2:19

Low pressure differences between the Arctic and mid-latitutde regions define the negative phase of the Arctic Oscillation and often bring cold temperature to North America, Europe, or northern Asia. Much colder-than-average temperature during March and a strongly negative Arctic Oscillation Index reminded people in the United States how important this index is to our own climate conditions. A year ago, the positive phase of the oscillation was in play during March, and conversely warmer-than-average temperature blanketed the United States.