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Y. Zyulyaeva, and S. K. Gulev

Diagnostics of the Major Sudden Stratospheric Warming events in different modern era reanalyses

Sudden Stratospheric Warming (SSW) events associated with the distortion of the polar vortex and the abrupt temperature increases in stratosphere represent one of the most remarkable climate phenomena in winter. SSWs may play an important role in forming circulation anomalies in the troposphere affecting near surface weather and climate, including extreme events. We use different first generation and modern era reanalyses (NCEP, ERA-Interim, MERRA, CFSR, 20CR) for the diagnostics of these events. As a major tool we use the concept of the 3D Eliassen-Palm Flux (EPF) and account also for the vertical component of EPF which allows for the explicit localization of the vertical propagation of the warming signal in the stratosphere. Different reanalyses are not completely replicating statistics of SSW events with some (e.g. NCEP-NCAR) being not capable of capturing some of them. Furthermore, in different products starting dates of SSWs can deviate from each other by several days. Considering the recent major SSW of 2009, we analyze the duration, intensity (polar- mid latitude gradient), timing of the peak intensity and the dynamics of the wave propagation (quantified using EOF analysis) in different reanalyses. Manifestation of the potential links of SSW events with the ocean climate signals and tropospheric processes in different reanlayses is also considered.

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