VATIS UPDATE Article

According to the researchers of the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research, Germany, in the past weeks an extreme cold spell in the Arctic stratosphere has created conditions that might cause severe ozone depletion over the Arctic in March – if the next few weeks will not bring a significant warming. “At about 20 kilometres altitude over the Arctic, the air has been as cold as minus 90 °C for weeks. Since the beginning of December, above our Arctic research station on Spitzbergen the mean temperature in the stratosphere has been 8 °C below the long-term average and 2 °C below the previous minimum. These are conditions that can result in substantial ozone depletion”, said Dr. Marion Maturilli, at AWI.

Model calculations performed by AWI researchers based on the extreme cold spell in recent weeks show that the chemical conditions in the Arctic stratosphere already now exceed the ozone depletion potential of the 2010/2011 winter. “The air masses with these unusual conditions are currently caught in a low-pressure vortex high over the Arctic. Transport of ozone into the vortex has also been low and an ozone minimum has already started to develop. By mid-February more than a quarter of the total ozone above the Arctic will have been destroyed chemically. Should the vortex persist until well into March, the formation of a deep ozone minimum over the Arctic has to be expected. However, if the vortex breaks up before then, the air masses will sufficiently mix with fresh air from lower latitudes and the Arctic will narrowly avoid a new record of ozone depletion,” explained Dr. Markus Rex, at AWI.