St. PETERSBURG, Aug 29 Scientists from St. Petersburg State University (SPbSU) have made unique measurements of tropospheric ozone concentrations in the atmosphere over St. Petersburg over the past 13 years and determined that the concentrations of this type of ozone are declining, the university reports.
“Scientists from St. Petersburg University, having carried out unique measurements of tropospheric ozone concentrations in the atmosphere over St. Petersburg over the past 13 years, have concluded that the concentrations of this type of ozone are decreasing, which leads to a decrease in the greenhouse effect,” the report says.
The university recalled that the ozone layer protects the Earth from the harmful effects of UV radiation. However, ozone can be not only «good» but also «bad». The second type includes tropospheric ozone (TO), which is contained in a volume of 10% in the lower part of the atmosphere — the troposphere. It is noted that tropospheric ozone is a toxic atmospheric pollutant, plays a key role in chemical and photochemical processes in the troposphere, and is also one of the main greenhouse gases affecting the radiation balance and climate change.
It is noted that in St. Petersburg, ground-level ozone concentrations (SOCs) are regularly measured at a number of stations, including the one at St. Petersburg State University in Peterhof. This data is used to assess air quality. Direct measurements of tropospheric ozone at St. Petersburg State University are unique for St. Petersburg.
“We carried out long-term measurements of the content of VCO and TO, and also studied their correlations with each other in St. Petersburg. According to our measurements, a statistically significant decrease in the content of TO by 0.34±0.22% per year was obtained, which in its turn indicates a decrease in the contribution of tropospheric ozone to the greenhouse effect in the region,» said Yana Virolainen, senior researcher at the Laboratory for the Study of the Ozone Layer and Upper Atmosphere of St. Petersburg State University, whose words are quoted in the message.
According to research, the highest concentrations of TO and VQS were observed in April of each year. This is due to the global Breuyer-Dobson air circulation, according to which there is a slow current in the northern hemisphere that redistributes air from the tropics to higher latitudes. Toward the end of July, a secondary maximum of the TO content is also periodically observed, associated with high surface temperatures and an increase in insolation, which contribute to the generation of ozone near the surface, its subsequent accumulation and mixing with the layers of the free troposphere.
The study was carried out within the framework of a grant from the Russian Science Foundation in the Laboratory for Research on the Ozone Layer and Upper Atmosphere of St. Petersburg State University, created as part of the mega-grant program of the Ministry of Science and Higher Education of the Russian Federation.