On the stratospheric dynamics in spring and summer : a tropics/poles coupling study

• Main Author: Thiéblemont, Rémi
• Other Authors: Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales Paris (CNES), Université d'Orléans, Nathalie Brun-Huret
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2012
• Subjects: Stratosphere; Intrusions; Advection model; Wave activity; Anticyclone; Spring; Stratosphère; Intrusions de masses d'air; Modèle de transport; Activité ondulatoire; Anticylone; Printemps; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Arctic
• Online Access: https://theses.hal.science/tel-00801758; https://theses.hal.science/tel-00801758/document; https://theses.hal.science/tel-00801758/file/remi.thieblemont_2755.pdf

The stratosphere dynamics remains largely unexplored in summer and spring. In the context of the ozone layer recovery and the increasing of greenhouse gases emissions, efforts must be provided to improve our knowledge of the dynamical processes driving the stratosphere. Such improvements would lead to better future climate trends estimates. Recently, spring and summer satellites observations revealed occurrences of irreversible air masses transport from the tropics to the Arctic region. However, the associated mechanisms are poorly understood. The present work consists of dynamical and climatological analyses of these events in order to identify their causes and their occurrence frequency. In particular, we focused on the sporadic events, where the intrusion signal persists several months in the polar region, trapped within an anticyclonic anomaly before disappearing in summer. We used MLS/Aura and MIPAS/ENVISAT satellites data, the SPIRALE balloon borne data and the results of the advection model MIMOSA to identify, characterize and quantify these events. Stratospheric dynamical conditions are investigated using the reanalyses data of the ECMWF. Finally, a systematic algorithm to detect low-latitude intrusions has been developed and applied on MIMOSA results to perform a climatology between 1980 and 2011 The results suggest that the frequency of these events, driven by the planetary wave activity, is increasing since the 21st century. Furthermore, their occurrence in spring appears to depend on the stratospheric dynamical evolution during winter and on the tropical region dynamical regime. La dynamique de la stratosphère au printemps et en été reste à ce jour largement inexplorée. Or dans les contextes actuels du recouvrement de la couche d’ozone et de l’augmentation des émissions de gaz à effet de serre, une amélioration de la compréhension des processus dynamiques contrôlant la stratosphère s’avère nécessaire, afin de mieux appréhender l’évolution du climat dans le futur. Des observations satellitaires ...