Air currents in the atmosphere affect sea ice extent in the Arctic

Changes in air currents in the atmosphere has a great effect on the sea ice extent in the Arctic. Direct effect on the sea ice can be seen when the circulation patterns change. Scientists can determine this based on satellite data.

The sea ice of the Arctic has only once before had a smaller minimum extent than this year. Scientists have compared the sea ice extent with changes in air currents and atmospheric conditions by using satellite data and could thereby establish that the atmosphere has a great effect on the sea ice.

"This year we have had severe warming during the late winter and spring and circulation changed somewhat so that warm winds blew over Siberia and brought in warm and humid air over Barents Sea and the Kara Sea in the Arctic Ocean. Its effects can be seen on the ice as its spread in this area is less than in previous years,” says Abhay Devasthale, researcher in atmospheric remote sensing at SMHI.

In recent decades, the sea of ice over the Arctic has become thinner and more sensitive to short-term changes in atmospheric conditions.

Winter is important for the ice

The conditions governing the size of the sea ice extent for the following summer are already decided during the winter season.

“Despite more warming occurring during the summer, the warming in the winter and summer have significant impact. Warm periods in the winter and spring prevent the ice from expanding, making it more sensitive to short-term changes in the weather and earlier melting,” says Abhay Devasthale.

Over the past decade using models and data from re-analyses, researchers have shown that in the short term, changes to the atmosphere’s circulation have bigger and faster effects on sea ice than changes in the sea. The oceans continue to have the greatest effect on the long-term ice variation.

Cloud coverage is increasing

Satellite data reveal that as sea ice disappears, cloud coverage increases as open water can provide the atmosphere with more moisture. This also influences the conditions for sea ice, as the clouds can retain warmth that radiates from the earth throughout the autumn and winter.

The Arctic sea ice extent has been compared to the average values for the years 1981-2010. 2001 was the last time that the sea ice extent was higher than average in the comparison period, at the time with the lowest sea ice extent. The lowest level of Arctic sea ice extent was in 2012.