EARTH SYSTEM PHYSICS - GUEST SEMINAR - TUESDAY 18 NOV.

[Earth System Physics Section]

EARTH SYSTEM PHYSICS SEMINAR
Tuesday, 18 November 11:00 a.m.
Stasi Lecture Room, Leonardo da Vinci bldg., 1st floor

Guest speaker
Paolo RUGGIERI
INFN
L'Aquila, Italy

IMPACT OF BARENTS-KARA SEA ICE VARIABILITY ON THE EURO-ATLANTIC SECTOR

The rapid decline of sea ice cover in the Arctic has instilled great interest into the atmospheric dynamics related to the so-called Arctic Amplification (i.e. the Arctic warms faster than the rest of the globe). We analysed the influence of sea ice concentration in the Barents and Kara seas on the weather in the extra-tropics. Both observations and model simulations show evidence of a link between sea ice variability and the weather in the midlatitudes. Our purpose is to investigate the response in terms of two-metre temperature and total precipitation over Europe, establishing a link between Barents-Kara variability and weather regimes in the Atlantic Sector. The study is based on data from Era-Interim, the European Centre for Medium-Range Weather Forecasts atmospheric reanalysis, and from the Global Precipitation Climatology Centre gridded dataset of the Deutscher WetterDienst.
We make a composite analysis of five "light ice" years and five "heavy ice" years. An index based on the low-level jet in the Atlantic Sector is used to explore the response during different regimes. Blocking indices and analysis of the atmospheric circulation lead us to some noticeable results: we find that light ice years are associated with enhanced high latitude blocking activity and symptoms of a slower and more persistent circulation. A case study is also presented to explain the physical mechanism which links the sea-ice anomaly with the atmospheric circulation in the North Atlantic Sector.
These results, since they are based on a longer period than the earlier studies, provide more robust indications of the effects that changes in Barents-Kara sea ice variability can have on European weather. As a further step towards a more complete understanding, we suggest a set of model simulations that could confirm the validity of our conjecture.

Everyone is most welcome to attend.