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Role of Finite-Amplitude Eddies and Mixing in the Life Cycle of Stratospheric Sudden Warmings
Bring Back 1962-63 posted a topic in Research PortalRole of Finite-Amplitude Eddies and Mixing in the Life Cycle of Stratospheric Sudden Warmings Authors: Sandro W. Lubis, Clare S. Y. Huang, Noboru Nakamura, Nour-Eddine Omrani and Martin Jucker Published: 26th October, 2018 Abstract: Despite the advances in theories and data availability since the first observation of stratospheric sudden warmings (SSWs) in the 1950s, some dynamical aspects of SSWs remain elusive, including the roles of wave transience at finite amplitude and irreversible wave dissipation due to mixing. This is likely due to a limitation of the traditional theory for SSWs that is tailored to small-amplitude waves and is unsuitable for large-scale wave events. To circumvent these difficulties, the authors utilized a novel approach based on finite-amplitude wave activity theory to quantify the roles of finite-amplitude wave transience and mixing in the life cycle of SSWs. In this framework, a departure from the exact nonacceleration relation can be directly attributed to irreversible mixing and diabatic forcings. The results show that prior to the warming event, an increase in pseudomomentum/wave activity largely compensates for the anomalous Eliassen–Palm flux convergence, while the total wave dissipation due to mixing (enstrophy dissipation) and radiative forcing only plays a secondary role. After the vortex breaks down, enhanced mixing increases irreversible wave dissipation and in turn slows down vortex recovery. It is shown that (i) a rapid recovery of the polar vortex is characterized by weak wave transience that follows a nonacceleration relation reversibly and (ii) a delayed recovery is attributed to stronger and more persistent irreversible wave dissipation due to mixing, a deviation from the classical nonacceleration relation. The results highlight the importance of mixing in the asymmetry between breakdown and recovery of the polar vortex during SSWs. Link to full paper: This is behind an AMS paywall but there is another link to the Researchgate site with the early online release with the full "preliminary" version from September 2018 (just scroll down that page) and there is also a personal pdf download version available from there. https://www.researchgate.net/publication/327854069_Role_of_Finite-Amplitude_Eddies_and_Mixing_in_the_Life_Cycle_of_Stratospheric_Sudden_Warmings