Shifting El Ni?o inhibits summer Arctic warming and Arctic sea-ice melting over the Canada Basin

摘要

Arctic climate changes include not only changes in trends and mean states but also strong interannual variations in various fields. Although it is known that tropical-extratropical teleconnection is sensitive to changes in flavours of El Ni?o, whether Arctic climate variability is linked to El Ni?o, in particular on interannual timescale, remains unclear. Here we demonstrate for the first time a long-range linkage between central Pacific (CP) El Ni?o and summer Arctic climate. Observations show that the CP warming related to CP El Ni?o events deepens the tropospheric Arctic polar vortex and strengthens the circumpolar westerly wind, thereby contributing to inhibiting summer Arctic warming and sea-ice melting. Atmospheric model experiments can generally capture the observed responses of Arctic circulation and robust surface cooling to CP El Ni?o forcing. We suggest that identification of the equator-Arctic teleconnection, via the ‘atmospheric bridge’, can potentially contribute to improving the skill of predicting Arctic climate.