Absorbing- and reflecting sudden stratospheric warming events and their relationship with tropospheric circulation: Case studies

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Wednesday, 7 January 2015: 4:30 PM
212A West Building (Phoenix Convention Center - West and North Buildings)
Kunihiko Kodera, Nagoya University, Nagoya, Japan; and H. Mukougawa, P. Maury, K. Matthes, M. Ueda, and C. Claud

The sudden stratospheric warming (SSW) events newly draw attention since their impacts on the troposphere became evident. Studies on the SSWs have been usually focused on the polar stratospheric condition, however, to understand their global impact, it needs to capture the phenomenon in a larger context. Case studies are made to clarify the characteristics in the stratosphere-troposphere dynamical coupling, especially the meridional extent of the phenomenon associated with the SSW.

The result shows that SSWs can be classified into two distinct types: One is the absorbing type SSW having a longer time-scale as well as larger meridional extent due to the persistent incoming planetary waves from the troposphere. This absorbing type SSW is related with the annular mode on the surface through poleward and downward migration of the deceleration region of the polar-night jet. The other one is the reflecting type SSW characterized by a quick termination of the warming due to the reflection of planetary waves in the stratosphere, which leads to an amplification of tropospheric planetary waves and induces Pacific blocking .