ИСТИНА

At Moscow University Meteorological observatory the vertical ‘ECHO-1’ SODAR of GDR production operates since 1988. It allows determining of the ABL thermal stratification including both surface and elevated inversions and measuring of their margins with a high accuracy (vertical resolution is 12.5 m) in the range up to 800 m above the ground. At the same location special ecological station of IAP and MSU operated from 2002 to 2014 at which surface contents of minor air gases (ozone, nitrogen oxides, carbon oxide, sulphur dioxide, etc.) were measured continuously with once a minute temporal resolution. As a result an influence of both morning short-living elevated (former nocturnal) inversions, and long-living elevated subsidence ones on the air pollution levels was studied. According to the data obtained, in the presence of short-lived elevated inversions, the surface ozone in the morning increases on average, whereas other gases (NO2 and CO which are products of fuel combustion from low sources, mostly from traffic) decreases. The maximum in the value of the first ozone derivative (growth acceleration) is observed on the average during the first few minutes after the moment of inversion destruction, which proves the essential role of dynamical factors in changes of the O3 content (its influx to the ground air layer from the middle troposphere). As for nitrogen dioxide, on the contrary, the moment of inversion destruction is associated on average with acceleration in the reduction of the NO2 surface content due to upward dispersion of this gas. For the first time, based on long-term data, an analysis of the effect of long-lived elevated inversions on the dynamics of minor air gases was made. According to the SODAR data, about 40 cases of elevated inversions which existed during 20 hours or longer were detected from 2002 to 2014, mostly – during cold season from November to January. As a rule they were subsidence inversions. As a result, in conditions of their existence in the lower 800 m air layer no statistically significant changes in the surface content of both ozone and nitrogen dioxide were detected (unlike conditions of short-lived morning inversions). A possible explanation of this result is an influence of other factors (e.g., precipitation), as well as the weakening of the influence of elevated inversions having too high base height or too thin layer between their base and top. This work was supported by the Russian Science Foundation (project 16–17–10275).