Variability of the Lagrangian turbulent diffusion in the lower stratosphere B. Legras1, I. Pisso1, G. Berthet2, and F. Lefèvre2 1Laboratoire de Météorologie Dynamique, UMR8539, Paris, France 2Service d’Aéronomie, UMR7620, Paris, France
Abstract. 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.
Citation: Legras, B., Pisso, I., Berthet, G., and Lefèvre, F.: Variability of the Lagrangian turbulent diffusion in the lower stratosphere, Atmos. Chem. Phys., 5, 1605-1622, doi:10.5194/acp-5-1605-2005, 2005.