Variability of the Lagrangian turbulent diffusion in the lower stratosphere

Bernard Legras (1) , Ignacio Pisso (1) , Gwenaël Berthet (2) , Franck Lefèvre (2)

1 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)
2 SA - Service d'aéronomie

Ozone and nitrous oxide are measured at high spatial and temporal resolution by instruments flying on the ER-2 NASA research aircraft. Comparing the airborne transects to reconstructions by ensemble of diffusive backward trajectories allows estimation of the average vertical Lagrangian turbulent diffusion experienced by the air parcels. The resulting estimates show large Lagrangian diffusion of the order of 0.1in the surf zone outside the polar vortex and smaller values of the order of 0.01 inside. Locally, large variation of Lagrangian diffusion occurs over mesoscale distances. It is found that high temporal resolution (3h or less) is required for off-line transport calculations and that the reconstructions are sensitive to spurious motion in standard analysed winds.

Domaines: Océan, Atmosphère

Bernard Legras, Ignacio Pisso, Gwenaël Berthet, Franck Lefèvre. Variability of the Lagrangian turbulent diffusion in the lower stratosphere. Atmospheric Chemistry and Physics, 2005, 5 (6), pp.1605-1622. ⟨hal-00328391⟩