Using ECWMF ERA-40 and Interim reanalysis data, the planetary wave fluxes associated with the February extreme stratospheric polar vortex were studied. Using the three-dimensional Eliassen-Palm (EP) flux as a measure of the wave activity propagation, the authors show that the unusual warm years in the Arctic feature an anomalous weak stratosphere-troposphere coupling and weak downward wave flux at the lower stratosphere, especially over the North America and North Atlantic (NANA) region. The extremely cold years are characterized by strong stratosphere-troposphere coupling and strong downward wave flux in this region. The refractive index is used to examine the conception of planetary wave reflection, which shows a large refractive index (low reflection) for the extremely warm years and a small refractive index (high reflection) for the extremely cold years. This study reveals the importance of the downward planetary wave propagation from the stratosphere to the troposphere for explaining the unusual state of the stratospheric polar vortex in February.
机构:
Charles Univ Prague, Fac Math & Phys, Dept Atmospher Phys, V Holesovickach 2, CR-18000 Prague 8, Czech RepublicUniv Leipzig, Inst Meteorol, Stephanstr 3, D-04103 Leipzig, Germany
Pisoft, Petr
Sacha, Petr
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Charles Univ Prague, Fac Math & Phys, Dept Atmospher Phys, V Holesovickach 2, A-1180 Vienna, Austria
Charles Univ Prague, Fac Math & Phys, Dept Atmospher Phys, V Holesovickach 2, CR-18000 Prague 8, Czech Republic
Univ Vigo, Fac Sci, EPhysLab, Campus As Lagoas S-N, Orense 32004, SpainUniv Leipzig, Inst Meteorol, Stephanstr 3, D-04103 Leipzig, Germany
Sacha, Petr
Kuchar, Aleg
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Charles Univ Prague, Fac Math & Phys, Dept Atmospher Phys, V Holesovickach 2, CR-18000 Prague 8, Czech RepublicUniv Leipzig, Inst Meteorol, Stephanstr 3, D-04103 Leipzig, Germany
机构:
Center for Atmospheric Science,University of CambridgeKey Laboratory of Middle Atmosphere and Global Environment Observation,Institute of Atmospheric Physics,Chinese Academy of Sciences