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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