Strange mystery of Antarctica's disappearing snow solved
File photo.
Digital Reporter
Monday, October 19, 2015, 6:00 PM - A new study has found that 80 billion tonnes annually -- roughly 90% -- of the snow in sections of eastern Antarctica is being vapourized by powerful winds. The findings contradict the previously-held belief that the snow was simply being blown around and re-deposited elsewhere in the region.
The research means scientists will have to adjust their projections about how much mass Antarctica is losing.
The snow is being lost in wind-scour zones -- areas which cover approximately 7% of Antarctica. They occur when winds consistently scrape at the surface over a period of many years, sometimes centuries.
Researchers were able to identify thousands of wind-scour zones using satellite imagery. In one of them, wind wiped out 18 metres of snow, roughly equal to two years' accumulation.
The team was led by Indrani Das, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory. For their study, the researchers identified new processes for analyzing wind-scour zones.
Ice-penetrating radar profile over a wind-scour zone demonstrating how ice sheet layers are cut off by winds. Credit: Indrani Das
Scour zones are created by persistent katabatic winds. That, combined with Antarctica's harsh climate, causes the wind to break up brittle snow.
While some blows away, the new findings show a significant amount sublimates, evaporating from a solid to a gas without reaching the liquid stage.
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Das believes this process has caused climate models to overestimate Antarctica's surface mass by more than 80 million tonnes annually.
"This impacts the surface snow-accumulation estimates of most major glaciers and ice streams of East Antarctica," Days says in a statement.
"There is this huge misconception that everything removed from scour zones is redeposited."
The driest place on Earth
"What we're seeing is that East Antarctica – already among the driest regions on earth – is a bit drier than we thought," study co-author Ted Scambos says in a statement.
"It's more likely that it is losing ice, and adding to sea level."
The climate modelers who were involved in the study plan to use the data to increase the resolution of their models. They expect the update to be complete in 2016.
A complete paper on the findings was published October 12 in Geophysical Research Letters.
Sources: Phys.org | Geophysical Research Letters
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