CETEMPS Observartory detects a decrease of stratospheric ozone over Italy. Although significant, the decrease does not represent a concern for human health. In the frame of an agreement with the Ministry of the Environment, CETEMPS has been running an ozone sounding station in the last few years in L'Aquila (Casale Calore). By means of stratospheric baloons CETEMPS monitors the vertical profile of ozone concentration.
Ozone (O3) is more abundant in the stratosphere, where it shields the Earth surface from the most harmful fraction of the Sun ultraviolet radiation.
Figure 1. The trajectory (red line) of the baloon sonde launched by CETMEPS on 14 Aprile 2011. The ozone sonde was launched from CETEMPS Observatory in L'Aquila, reached a maximum altitude of 34.8 km, and then landed near Agnone (Isernia).
The ozone sounding of April 14th 2011 (see trajectory in Figure 1) revealed an anomaly in the vertical profile of ozone, in particular at 15 km and in the upper stratospheric layers (above 22 km altitude), with concentrations lower than the climatological profile relative to the same period (Figure 2). The measurement is representative of an area that covers Central and Southern Italy.
Figure 2. Vertical profile of ozono concentration observed on Central and Southern Italy on 14 Aprile 2011 (yellow line) compared with the climatological profile of April (white line). At 15 km and above 22 km a decrease of about 10% with respect to climatology is observed.
A possible explaination of the decrease is linked to the stratospheric arctic air (particularly depleted in ozone this year) that reached our low latitudes.
The effect of this stratospheric ozone decrease is not negligible, but at the moment it does not alter significantly the UV fraction reaching the ground. Such phenomena are however potentiallt harmful and is thus important to assess their impact and recurrence.