Лëд и снег (Mar 2015)
Climatic variations of the Arctic front and the Barents sea ice cover in winter time
Abstract
Climatologic Arctic front location at Atlantic-European section and changes in Barents sea ice coverage during periods of Arctic warming (1981–2010) and cooling (1948–1980) are studied 7by reanalysis data (UEA CRU and NCEP/NCAR). As we demonstrate, Arctic front structure is more complex than was considered before. Arctic front consists of two branches, main one over Atlantic ocean, Norwegian and Barents seas and secondary one over Northern Europe. Main front divides arctic and temperate air masses over Atlantics as well as arctic and subarctic (transformed temperate masses over Northern Europe) masses over Arctic seas. Secondary (subarctic) branch separates subarctic air masses from continental temperate masses. Main and secondary Arctic front branches remain quasi-stationary during observed periods. On climatic scale, Arctic front is conservative with respect to cyclonic activity change during periods of warming and cooling in Arctic. Cyclonic activity, which is determined by cyclone centres repeatability, increased synchronously in Arctic and Subarctic from cooling period (1948–1980) to actual warming. Evidences to meet hypothesis on positive feedback between warm Atlantic water masses inflow and Barents sea wintertime ice coverage. This hypothesis became particularly important in relation with model reproduction of turbulent warm heavy stream that cause convection and cyclonic turbulence in lower troposphere. In feedback forming, cyclone centres localization matters; their repeatability is calculated for climatic episodes 1991–2007 (small ice coverage) and 1979–1990 (big ice coverage) in Barents sea’s four sections. During climatic episode 1991–2007 cyclone centres repeatability increased mostly in western sections, while in eastern sections repeatability decreased. At the same time, cyclone localization increase mostly in north-west section, comparing with south-western one. Cyclone centres localization shift north cause ice coverage decrease there.
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