Quarter 1 of 2020 Produces Strongest Arctic Oscillation on Record
Fig. 1: The strongest quarter 1 positive phase arctic oscillation on record occurred in 1989, 1990 and 2020.
Discussion: Rare are 3 consecutive months of the same intense polar vortex location during the winter season. However, the lack of displacement of the polar vortex from the North Pole during winter 2019-20 was a leading catalyst to the increased mild maritime influence across most of the continental northern hemisphere causing a record warm winter. The intense polar vortex near the North Pole is identified by a persistent robust positive phase of the arctic oscillation during quarter 1 of 2020 matched only by 1989 and 1990 in the historical climatology (Fig. 1). Interestingly, the winter of 1988-89 and 1989-90 occurred during one of the strongest solar maxima on record while winter 2019-20 was just the opposite…one of the strongest solar minima on record (Fig. 2).
Fig. 2: The 1988-89/1989-90 strong positive winter arctic oscillation occurred during one of the strongest solar maxima on record. An equally strong +AO during winter 2019-20 occurred with strongly diminished solar activity.
In a classic example of climate change, the +AO regime of Q1/2020 has produced near-record or record warmth across Eurasia and the eastern half of the U.S. (Fig. 3). The cold temperatures beneath the intense polar vortex are confined to Greenland and far northern Canada. However, note that a similar +AO regime occurring during Q1 of 1989 and 1990 caused a much wider cold exposure across the northern latitudes and particularly Canada while the middle latitude warming was not as impressive (Fig. 4-5). The polar ice cap was somewhat larger during Q1 of 1989 and 1990 enabling the far northern polar vortex to produce more widespread chill.
Fig. 3-5: The 1988-89/1989-90 strong positive winter arctic oscillation occurred during one of the strongest solar maxima on record. An equally strong +AO during winter 2019-20 occurred with strongly diminished solar activity.