Southern Hemisphere (SH) climate variations in the past thirty years are strongly driven by ozone long-term changes in the austral spring-summer season. Specifically, the stratospheric ozone depletion over Antarctica has led to a long-term cooling of the stratosphere that seasonally superimposes to the GHG cooling. The polar lower-stratospheric cooling has contributed to the strengthening of the westerly winds in the polar vortex and the delaying of the seasonal transition from winter westerlies to summer easterlies. This perturbation of the lower stratosphere also impacts the troposphere, by accelerating and poleward shifting the mid-latitude tropospheric jet, and projecting onto the positive phase of the Southern Annular Mode (SAM). We show, through a multi-model analysis, that a limited representation of stratospheric processes (dynamics and chemistry) in the Coupled Intercomparison Project Phase 5 (CMIP5) models leads to a bias in the representation of simulated SH stratospheric and tropospheric long-term changes.

This event is part of the eventgroup Seminar on selected topics in meteorology

Speaker
Dr. Chiara Cagnazzo

ISAC-CNR Rome, Italy

Organizer
Prof. Dr. J. Orphal
IMK-ASF
Karlsruher Institut für Technologie (KIT)
Karlsruhe
Tel: +49 721 608 29121
Fax: +49 721 608 24742
Mail: johannes orphal ∂does-not-exist.kit edu

Targetgroup
Scientific Staff