During winter and spring the Arctic stratosphere is dominated by a stable polar vortex within which halogen from anthropogenic sources leads to rapid photochemical processing triggering substantial loss of polar ozone over the course of most winters. These processes are facilitated by the dynamical isolation of the vortex whose edge represents a transport barrier inhibiting the exchange with midlatitude air. However, in the Arctic, wave breaking associated with major stratospheric warming events episodically destabilizes the vortex sometimes leading to large-scale transport of processed vortex air to midlatitudes and to intrusions of midlatitude air into the vortex with effects on chemical composition in both regions. Subsequently small-scale irreversible mixing determines the fate of the transported air masses. Observations of chemical tracers help to investigate and quantify the transport and mixing processes in question. In situ measurements of a suite of long-lived tracers were made with the University of Wuppertal's HAGAR instrument on board the M55 Geophysica aircraft in the Arctic UTLS (up to 20 km altitude) during January through March 2003 and 2009 (EU campaigns EUPLEX and RECONCILE). During both these winters the polar vortex was dynamically very active, splitting and reforming due to major warming events. The tracer observations are used along with simulations by the Lagrangian chemical transport model CLaMS to analyze both large-scale isentropic transport and small-scale irreversible mixing. Furthermore the composition of the Arctic lowermost stratosphere below the polar vortex is assessed, quantifying fractions originating from the vortex, the midlatitude stratosphere, and the troposphere.

Diese Veranstaltung ist Teil der Reihe Karlsruher Meteorologisches Kolloquium

Referent/in
Prof. Dr. C. Michael Volk

Bergische Universität Wuppertal
Prof. for Experimental Atmospheric - FB C - Department of Physics

Veranstalter
IMK-ASF
Karlsruher Institut für Technologie (KIT)
Eggenstein-Leopoldshafen
E-Mail: sekretariat ∂does-not-exist.imk-asf kit edu

Zielgruppe
Wissenschaftliche Mitarbeitende