Atmospheric rivers trigger surface melt in West Antarctica

Recent events of ice melt in West Antarctica are concerning as these events indicate potential surface melt of ice shelves and their consequent collapse.

A recent study by European researchers investigated the relationships between ice melt in West Antarctica and atmospheric rivers. These atmospheric events consist in narrow and elongated bands associated with elevated transport of water vapor that travel from tropical regions to high latitudes. When the jet stream becomes wavier, the extratropical cyclones around Antarctica transport the atmospheric rivers toward the continent. These events bring heat and humidity and, when they reach land, they can affect the surface of Antarctica.

Using an algorithm to detect atmospheric rivers developed for Antarctica in synergy with observations of ice melt, this study produced a climatology of ice melt events related with atmospheric rivers from 1979 to 2017. To analyze the distribution of events and the associated impacts, Antarctica was divided in four quadrants. The focus of this study were the two quadrants that cover the West Antarctic region – West Antarctic Ice Sheet (WAIS) and Antarctic Peninsula and Weddell Sea (AP-Weddell).

The results showed that atmospheric rivers are associated with increased probability of ice melt events. Although atmospheric rivers are rare events in West Antarctica (around 12 per year), these are associated with approximately 40 % of ice melt in Ross Ice Shelf up to 100 % in higher regions of Marie Byrd Land in the summer, and 40 to 80 % of ice melt on the Wilkins, Bach, George VI and Larsen B and C ice shelves in the winter.

The largest ice melt events in WAIS occur only a few times per decade. Yet, the warming and continuous increased activity of atmospheric rivers can increase the frequency of ice melt events with consequences for the stability of Antarctic ice shelves.


Source: Wille, J. D., Favier, V., Dufour, A., Gorodetskaya, I. V, Turner, J., Agosta, C. and Codron, F. 2019, West Antarctic surface melt trigered by atmospheric rivers, Nature Geosciences, 12, 911–916, DOI: 10.1038/s41561-019-0460-1

Author: Carolina Viceto


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