Observation of Polar Stratospheric Clouds down to the Mediterranean coast

[摘要] A Polar Stratospheric Cloud (PSC) was detected for the first time in January2006 over Southern Europe after 25 years of systematic lidar observations.This cloud was observed while the polar vortex was highly distorted duringthe initial phase of a major stratospheric warming. Very cold stratospherictemperatures (<190 K) centred over the Northern-Western Europe werereported, extending down to the South of France where lidar observationswere performed. CTM (Chemical Transport Model) investigations show that thisevent led to a significant direct ozone destruction (35 ppb/day), within andoutside the vortex as chlorine activated air masses were moved to sunlightregions allowing ozone destruction. If such exceptional events ofmid-latitudes PSCs were to become frequent in the future, they should notcompromise the ozone recovery because their effect appears to be limitedtemporally and spatially. More importantly, these events might tend to beassociated with the initial phase of a stratospheric warming that resultsinto a weakening and warming of the polar vortex and hence into a reducedprobability occurrence of PSC temperatures during the rest of the winter.

[学科分类] 大气科学