On the Maintenance of Atmospheric Blocking by Migrating Synoptic Cyclones: A Lagrangian and Wave Activity Perspective

Atmospheric blocking often causes weather extremes in the mid- to high-latitudes, yet its first-order dynamics are still not well understood. A key question is how migrating synoptic eddies contribute to the maintenance of atmospheric blocking, and whether such contribution is by chance or systematic. In this study, we will adopt a Lagrangian-based tracking methodology to capture the trajectories of cyclones by identifying the initiation, lifecycle, and trajectory of migrating synoptic eddies. We will also adopt an Eulerian-based local wave activity (LWA) to diagnose the pseudo-momentum carried by migrating synoptic cyclones and atmospheric blockings. Using LWA budget analysis, we will assess the amount of the wave activity each migrating cyclone brings to the development of atmospheric blocking throughout its lifecycle, and we will quantify conditional probability to understand the intrinsic connection between the cyclones and blocks. In a warming climate, as synoptic eddies are experiencing poleward propagation and slowdown, this work will help us better understand the future changes of atmospheric blocking and associated surface extreme weather events.