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Antarctic Regional Synopsis

Regional charts and associated synopsis write-up capture ice and environmental conditions throughout the Antarctic which are based on the U.S. National Ice Center’s weekly analysis. Charts and synopses are updated weekly on Fridays.

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Amery Region

There was very little change in the Amery Region this week. Westward drift was slight and there was only minimal movement caused by passing weather systems. The most activity occurred off the northern face of the Amery Ice Shelf, where localized winds kept the sea ice conveyor belt moving. As the sea ice at the edge pushed northward, the thinner ice types melted leaving first-year ice at the edge across much of the Amery Region.

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Amundsen Sea

The pack ice in the Amundsen Sea this week was wracked by 2 storms which helped to tear the ice apart in the central and western parts. The storms brought warm temperatures and northerly winds to the eastern Amundsen, compressing the ice edge southward 50–70 NM. The storm in the western Amundsen Sea enhanced the gyre rotation of the Ross Sea which caused the ice in the region to drift in a clockwise direction.

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Bellingshausen Sea

Sea ice in the Bellingshausen Sea was heavily influenced by a strong storm this week, as northerly winds brought warm temperatures from 0–2°C over most of the pack and forced the ice southward, causing it to compress and shrink in area. Peak sea ice extent typically occurs in late September, although it is possible it occurred a week early (last week) this year, with this week's warmth and ice area decline in the Bellingshausen evidencing the change of season.

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Ross Sea

The typical ice conveyor belt process continued this week off the Ross Ice Shelf and in Terra Nova Bay, while a katabatic event northeast of Cape Adare opened some polynyas in the first-year ice nearby. The pack ice experienced a strong northward motion near the border with the Amundsen Sea behind a passing trough. The cold air behind that trough caused rapid ice growth along the ice edge in the eastern Ross Sea, pushing the edge northward anywhere from 100–150 NM from the previous week. Further west, northerly flow brought temperatures near or slightly above freezing along the ice edge, melting some young ice and pushing the ice edge south up to 120 NM.

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Weddell Sea East

Katabatic winds exposed coastal waters which allowed for the rapid development of new and young ice near the coast. Along the ice edge in the eastern portion of the region, temperatures just above freezing prevented the formation of any additional new ice but were cold enough over the pack ice to sustain it. Near the Antarctic Peninsula below-freezing temperatures extended over the ice edge and allowed for the formation and development of new ice, but westerly winds helped to diffuse the ice edge and left ragged areas near the islands.

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Weddell Sea West

Katabatic winds exposed coastal waters which allowed for the rapid development of new and young ice near the coast. Along the ice edge in the eastern portion of the region, temperatures just above freezing prevented the formation of any additional new ice but were cold enough over the pack ice to sustain it. Near the Antarctic Peninsula below-freezing temperatures extended over the ice edge and allowed for the formation and development of new ice, but westerly winds helped to diffuse the ice edge and left ragged areas near the islands.

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Wilkes Land Region

A low pressure system moved across the area this week pushing the ice edge in places anywhere from 40–100 NM and shredding it in other places. Movement of the ice continued westward with only a slight change towards the northwest near the Amery Region. Cold temperatures persisted over the Wilkes Land Region, allowing ice growth in most places. The Antarctic sea ice extent maximum may have happened last week, bringing the start of the melt season.

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