S. Godin Beekmann

LATMOS IPSL, CNRS/UPMC

 

Differential Absorption Lidars are used at global scale for the monitoring of the stratospheric ozone layer within the Network for the Detection of Atmospheric Composition Changes (NDACC). Ozone lidar measurements are essential data sets for the study of the depletion of the ozone layer and its recovery in the context of the Montreal protocol and climate change. Long term DIAL ozone measurements are performed as part of NDACC at Observatoire de Haute-Provence (OHP), France (43.91°N, 5.71°E) since 1985, in Antarctica in Dumont d’Urville (66.4°S, 140°E) since 1991 and in La Réunion island (20°S, 120°E) since 2000. In addition to the study of long term ozone trends, the OHP lidar data have been used together with a high resolution transport model to evaluate the influence of Arctic ozone depletion on mid-latitude ozone amounts. In order to validate the simulations of the transport model, an airborne ozone lidar was also deployed to sample polar air filaments mixing into mid-latitude regions during two contrasting Arctic winters. In Antarctica, the lidar measurements were used to evaluate the subsidence of polar air in autumn and winter, and the rapid chemical ozone depletion in spring. Since Dumont d’Urville station is located close to the edge of the polar vortex, a detailed study of the permeability of the polar vortex as a function of altitude could be performed based on the ozone measurements. In La Reunion Island, close to the tropical transport barrier, lidar observations were used to make a detailed study of transport events across this barrier. NDACC ozone lidar time series measurements are also essential observations for the long term validation and cross-comparison of satellite instruments. The long term ozone lidar times series at OHP have been compared to various satellite measurements time series such SAGE II, HALOE or SBUV. Most recent validation exercises were performed for instruments on board ENVISAT, AURA and MetOp platforms. Finally, the longest NDACC lidar ozone time series, e.g. obtained at Hohenpeissenberg (Germany), OHP, Table Mountain and Hawaï (USA) and Lauder (New Zealand), have been used to evaluate the ozone recovery in the upper stratosphere in the context of climate change.