Abstract: Maximum stretching lines in the lower stratosphere around the Antarctic polar vortex are diagnosed using a method based on finite-size Lyapunov exponents. By analogy with the mathematical results known for simple dynamical ...

Abstract: We present a new statistical-dynamical approach to the concept of weather regimes, including the effect of tralisients, without any assumption other than scale separation. The method is applied to a quasi-geostrophic channel ...

Abstract: The forcing of low-frequency variability by synoptic transient traveling perturbations is investigated within a quasi-geostrophic channel forced by a localized baroclinic jet. Spontaneously generated baroclinic perturbations ...

Abstract: Two different definitions of midlatitude weather regimes are compared. The first seeks recurrent atmospheric patterns. The second seeks quasi-stationary patterns, whose average tendency vanishes. Recurrent patterns are ...

Abstract: The Lyapunov diffusivity is used to investigate local isentropic mixing events in the upper troposphere?lower stratosphere (UTLS) region. The diagnostic highlights the seasonal cycle of the longitudinally varying mixing ...

Abstract: A new diagnostic (the ?Lyapunov diffusivity?) is presented that has the ability to quantify isentropic mixing in diffusion units and detects local mixing events by describing latitude?longitude variability. It is a hybrid ...

Abstract: The ozone evolution in the lower stratosphere of the Southern Hemisphere during the period 5?10 August 1994 is analyzed. The analysis focuses on the ozone ?collar? (the band of maximum values in ozone mixing ratio around ...

Abstract: The EOLE experiment is revisited to study turbulent processes in the lower stratosphere circulation from a Lagrangian viewpoint and to resolve a discrepancy on the slope of the atmospheric energy spectrum between the work ...