University of Cambridge > > DAMTP Atmosphere-Ocean Dynamics > The Local Finite-Amplitude Rossby Wave Theory: Review, Development and Outlook

The Local Finite-Amplitude Rossby Wave Theory: Review, Development and Outlook

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The Finite-Amplitude Rossby Wave Activity (FAWA) formalism has been developed by Nakamura and collaborators since 2010. Not only does FAWA satisfy the exact nonacceleration relation, but it also allows a precise partition of FAWA tendency into advection, mixing (in terms of effective diffusivity) and forcing. Various studies applied this theory to identify factors that govern the eddy-mean flow interactions at midlatitudes in both general circulation models and reanalysis data. Recently, Huang and Nakamura (2016) generalized FAWA into a longitudinally local wave activity (LWA). As LWA quantifies waviness of potential vorticity (PV) contour at each longitude and satisfies an approximate local non-acceleration relation, it is a suitable candidate to diagnose localized phenomena such as atmospheric blocking.

In this presentation, I will first give a brief historical account of the development of finite-amplitude Rossby wave theory (i.e. previous work by Andrews, Haynes, Killworth, Shepherd and McIntyre) and how our LWA formalism incorporates these ideas. I will then review the (zonal mean) FAWA formalism and its application. Furthermore, I will outline our LWA formalism and demonstrate with reanalysis data how LWA captures the climatology of blocking and describes the life cycles of blocking episodes.

This talk is part of the DAMTP Atmosphere-Ocean Dynamics series.

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