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  Home - About Us - Valentia Observatory - Ozone Monitoring


Valentia Observatory

Weather BalloonOzone Monitoring
Valentia Observatory has been conducting Ozone measurements since 1993 and is currently one of an international network of sites involved in the monitoring of ground level, total column and stratospheric ozone.

Upper Air Monitoring Activities
The vertical distribution of ozone in the atmosphere is measured by balloon-borne ozonesondes, which are launched during winter and spring months. Additional ozonesonde launches are made as part of European-wide monitoring and field research programmes. As part of the GAW (Global Atmospheric Watch) Global Ozone Observing System the Observatory has played a very active role in EU funded research projects including, SESAME (the Second European Stratospheric and Mid latitude Ozone Experiment), TOASTE (the Tropospheric Ozone and Stratospheric-Tropospheric Exchange), FASTEX (the Fronts and Atlantic Storm Tracking Experiment) and THESOE (the Third European Stratospheric Ozone Experiment). More recently Valentia has been actively involved in the MATCH campaign which is part of the OSDOC (Ozone Soundings as a tool for Detecting Ozone Change) experiment.

Vertical Ozone Profile derived from Ozonesonde ascentVertical Ozone Profile derived from Ozonesonde ascent

Brewer spectrometerGround-based Monitoring Activities
Ground-based monitoring of total column ozone and UV-B radiation levels are continuously conducted at Valentia Observatory, using a Brewer spectrometer (right). These data contribute to the daily analysis of Northern Hemisphere total column ozone as produced by WMO Daily Ozone Mapping Centre (Thessaloniki, Greece) and the WOUDC (the World Ozone and UV Data Centre, Toronto, Canada).

Ground-level ozone is measured on a continuous basis using an API Model 400 Continuous UV Absorption Ozone Analyser. This monitoring is done as part of the national ground level ozone monitoring programme conducted by the EPA (Environmental Protection Agency).

Ozone is a gas, blue in colour and with a strong odour, which is formed by the action of ultra-violet light on oxygen. While ozone is present from the surface of the earth up to the stratosphere its concentrations are significant at two parts of the earth's atmosphere, at ground level and in the stratosphere at a height of between 17,000 and 23,000 meters where high concentrations occur. This high concentration is referred to as the ozone layer. The maintenance of this thin layer is essential for the health of humans, animals and plant life because it absorbs harmful ultra-violet radiation from the sun.

Seasonal dependence of Total Column Ozone at Valentia Observatory.Valentia Ozonegraph

Based on Spring 1993 to Spring 2000 final values.On the other hand, high levels of ozone at the ground are harmful. "Good up high, bad nearby" is a phrase that is often used to describe the value of ozone. At ground level ozone is a pollutant. Here it is formed during warm conditions and strong sunlight by reactions among nitrogen oxides, and volatile organic compounds from car exhausts and industry. Consequently, high concentrations of ground level ozone are often found in cities during the summer, where they contribute to smog and can cause chest pain, throat irritation and coughing.
Most of the world's ozone is formed near the equator, spreads out and is transported north and south by large-scale global circulations. The ozone layer is denser at high latitudes than it is over the tropics. The concentration of ozone at any location is prone to variations due to many factors, among them being seasonal changes and changes in prevailing air masses.

Ozone is destroyed naturally through the interaction of other gases in the stratosphere, and is replenished in the same cycle. This natural cycle is being interrupted by human activity such as the release of other gasses among them being Chloroflourocarbons (CFC's) and emissions of nitric oxide from aircraft.


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