Role of Atmospheric Variability in Driving the 'Warm-Arctic, Cold-Continent' Pattern Over the North America Sector and Sea Ice Variability Over the Chukchi-Bering Sea

摘要

While the observed decline of sea ice over the Chukchi-Bering Sea (CBS) has coincided with the "warm-Arctic, cold-continent" (WACC) pattern over the North America (NA) sector, there is a debate on the causes of the WACC pattern. Here we present a very similar WACC pattern over the NA sector on both inter-annual and subseasonal time scales. Lead-lag regression analyses on the shorter time scale indicate that an anomalous anticyclonic circulation over Alaska/Yukon in conjunction with the downward surface turbulent heat flux and long-wave radiation anomalies over CBS leads the formation of the WACC pattern by about 1 -2 days, while the latter further leads CBS sea ice reduction by about 3 days. These results indicate that atmospheric variability may play an active role in driving both the WACC pattern over NA and CBS sea ice variability.