Accueil > Actualités > Séminaires > Séminaire de Federico FIERLI au LATMOS


Titre : Variability and trend of the stratospheric subtropical barrier
Nom du conférencier : Federico FIERLI
Son affiliation : ISAC-CNR, Bologne, Italie
Laboratoire organisateur : LATMOS
Date et heure : 27-03-2012 11h00
Lieu : LATMOS/OVSQ, Amphithéâtre Gérard Mégie, 11 Bvd d'Alembert, 78280, Guyancourt
Résumé :

We analyse the average structure and the variability of the stratospheric dynamical barrier located in the subtropics. For this we use Probability Density Functions (PDFs) of the long-lived tracers nitrous oxide (N2O) and methane (CH4) from different satellite instruments: the Microwave Limb Sounder (MLS) on board Aura, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board Envisat, the Sub-Millimetre Radiometre (SMR) on board Odin and the Halogen Occultation Experiment (HALOE) on board UARS, overall covering the time period of 1992–2009. In addition we apply the same analysis to CCMVAL model data for the same set of tracers and within a compatible time window. We present the analysis of the consistency among the different datasets and their capability of identifying mixing regions and barrier-to-transport regions in the stratosphere and the subtropical barrier location. There is a strong seasonality consistently represented by observations and models, characterized by the wintertime shift of the subtropical edge toward the summer hemisphere; in addition the barrier position is modulated by the QBO, due to the role of planetary waves breaking and residual circulation. We conclude our analysis evaluating possible trends in the barrier morphology and position at decadal timescale.