Lagrangian Analysis of the Northern Stratospheric Polar Vortex Split in April 2020

The present study examines the northern stratosphere during April 2020, when polar vortex split into two cyclonic vortices a winter-early spring period with strongest ozone depletion on record. We investigate dynamical evolution leading to at middle stratospheric levels, including fate of fluid parcels boundary its rupture and distribution between resulting from split. also illustrate vertical structure after findings obtained Lagrangian methods confirm key role for played by flow special configuration barriers motion parcels. A trajectory analysis clarifies how was such that poorest air remained in main vortex. offspring had deep troposphere later decayed vanish end April.