Evolution and behaviour of the stratospheric and surface ozone in the southwest of Iberian Peninsula (El Arenosillo)

Atmospheric Sounding Station (ESAt) El Arenosillo is an International Reference Centre dedicated to the observation and analysis of various atmospheric parameters such as surface ozone and precursors, aerosols in situ and in column, stratospheric ozone and solar radiation, and various ionospheric parameters. In this paper the monthly and daily evolution is analysed, with a marked hourly cycle with higher levels in the central hours and in summer months. The surface ozone dynamics is strongly conditioned for the orography (coastal site), atmospheric conditions and sources of ozone precursors. Under mesoscale processes of air masses, surface ozone episodes are recorded with daily maximum up 160 g m-3. Total ozone content (TOC) measurements at El Arenosillo show a marked seasonality, with maximum peaks in spring, minimum values in autumn and yearly mean around 315 Dobson Units. Based on the observations, it has been determined that a marked TOC depletion can be observed during the 80s, stabilizing gradually in the decade of the 90s to get nowadays a positive trend towards the recovery of the ozone layer.