Recent reoccurrence of large open‐ocean polynya on the Maud Rise Seamount

Satellite observations have shown that the largest and most prolonged Maud Rise open‐ocean polynya since the 1970s appeared on 14 September 2017 (~9.3 × 103 km2) within the seasonal sea‐ice cover which expanded maximum on 1 December 2017 (~298.1 × 103 km2) and existed for 79 days. Record negative anomalies of sea‐ice concentration were observed in and around the polynya. The occurrence of the polynya was associated with a large cyclonic eddy and negative wind stress curl that facilitated melting of sea‐ice. Concurrently, a region of positive sea level pressure anomalies extended over the entire northern Weddell Sea accompanied by record low negative anomalies (deep depressions) over the southwest Weddell Sea and the Maud Rise. The atmospheric circulation anomalies advected moist‐warm air from the midlatitudes, resulted a record atmospheric warming (~11.5 °C) in the Maud Rise that favored this rare event as one of the largest open‐ocean polynyas.

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