The probability of snowy cold winters in Central Europe rises when the Arctic is covered by less sea ice in summer. Scientists of the Research Unit Potsdam of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association have made this discovery.
The scientist have decrypted a mechanism in which a shrinking summertime sea ice cover changes the air pressure zones in the Arctic atmosphere and impacts our European winter weather. If there is a larce scale melt in the summer, like in recent years, two important effects are intensified.
Firstly, the retreat of the light ice surface reveals the darker ocean, causing it to warm up more in summer from the solar radiation.
Secondly, the diminished ice cover can no longer prevent the heat stored in the ocean being released into the atmosphere (lid effect). As a result of the decreased sea ice cover the air is warmed more greatly than it used to be particularly in autumn and winter because during this period the ocean is warmer than the atmosphere.
"These higher temperatures can be proven by current measurements from the Arctic regions," reports Ralf Jaiser, lead author of the publication from the Research Unit Potsdam of the Alfred Wegener Institute. The warming of the air near to the ground leads to rising movements and the atmosphere becomes less stable.
“We have analysed the complex non-linear processes behind this destabilisation and have shown how these altered conditions in the Arctic influence the typical circulation and air pressure patterns," explains Jaiser.