Mesoscale variability of surface ozone dynamics in the south of Tomsk region Boris D. Belan, Denis K. Davydov, Denis E. Savkin, Tatyana K. Sklyadneva, Gennadii N. Tolmachev, Alexander V. Fofonov V.E. Zuev Institute of Atmospheric Optics, SB RAS, Tomsk, 634055, Russian Federation (bbd@iao.ru, +73822 492086) Motivation In the stratosphere, ozone serves a protective function preventing arrival of hard UV radiation to the Earth’s surface. In contrast, the tropospheric ozone that forms in situ in the atmospheric boundary layer is a substance belonging to the first class of danger. In high concentration, it strongly inhibits vital activity of plants and diversely affects the human body. Organization of ozone monitoring at 4 sities located in Tomsk region with different levels of anthropogenic load (urban, suburban and background) enables a comparison of mesoscale dynamics of ozone concentration to be done. Results and discussion Diurnal variations The amplitude of SOC diurnal variation depends on the season. There are two significant differences between the backgrounds stations and stations located close to the city. The maximum amplitude of diurnal and annual variation observed at stations, indicating a predominant role of photochemical processes in the of SOC production. Site description V.E. Zuev Institute of Atmospheric Optics has started continuous monitoring of the air composition, including surface ozone concentration (SOC), on September 1989 in the framework of TOR Project (Tropospheric Ozone Research) of the EUROTRAC Programme. At present, continuous measurements are carried out at four sites, which are located 5, 50, and 60 km from one another. Table 1. The coordinates of the measuring stations. Fig. 3. Diurnal behaviour of SOC averaged over the whole measurement period (averaged over 2009-2015 period). Station Coordinates TOR (Tropospheric Ozone Research) 56°28'41'' N, 85°03'15'' E BEC (Base Experimental Complex) 562849'' N, 850608'' E FON (Fonovaya Observatory) 562507'' N, 840427'' E BRZ (Berezorechka) 56°08'56'' N 84°19'58'' E Seasonal variations Fig. 4. Diurnal behaviour of the ozone concentration averaged for the middle months of each season (averaged over 2009-2015 period). Gradient measurements Fig.1. Location of ozone monitoring stations in the Tomsk region. Equipment Concentration of ozone at TOR-Station, Fonovaya Observatory, and BEC is measured with a JSC OPTEC 3.02 P-A chemiluminescence ozone analyzer, and with a DyLec model 1150 UV photometric ozone analyzer at Berezorechka site. All analysers are periodically calibrated by means of a JSC OPTEC GS-024 ozone generator. Table 2. Instrumentation JSC OPTEC 3.02 P-A Ozone monitor DyLec model 1150 1-500 µg/m3 Measure range Low 0-0,2 ppm High 0-0,5 ppm ±20% Accuracy ± 0,5% of F. S. (Full scale) Russia Place of Origin Japan Fig. 5. Annual mean behaviour of the ozone concentration measured at two heights AGL (averaged over 2009-2015 period) The concentrations of ozone at levels 10 and 30 meters are well correlated with each other at both stations. The correlation coefficient is 0.99 and 0.97 for BEC and FON, respectively. SOC at 30 m level higher than the 10 m level in the spring and summer at BEC and throughout the year at FON. Obviously, this phenomenon can occur due to sink of ozone to the underlying surface because the concentration at 30 m height for the year exceeds its value at 10 m level. Results and discussion Annual variations Analysis of the data obtained to date showed that the mean annual behaviour of the ozone concentration observed at Berezorechka site differs from one observed at three other sites. An unusual fact was found that at BRZ site distinct minima of the surface ozone concentration were observed in summer. Seasonal variation similar at BRZ and FO, on the one hand, and at BEC and TOR-Station, on the other hand. The spring ozone maximum at two stations (FON and BRZ) was observed in March, at that ozone concentration at BRZ was higher. Maximum at three other station occurred in April and was most likely caused by phytoncide emission from deciduous trees and herbage. Fig. 6. Diurnal behaviour of the ozone concentration measured at two heights AGL (averaged over 2009-2015 period) Diurnal variation of SOC at levels of 10 and 30 meters differ markedly in these areas. The difference in the ozone concentration higher between two levels in the background area Acknowledgements This work was funded by Russian Foundation for Basic Research (grant №14-05-00590), and Ministry of Education and Science of Russia (State Contracts №14.604.21.0100 (ID:RFMTFIBBB210290), №14.613.21.0013 (ID: RFMEFI61314X0013)). Fig.2 Annual mean behaviour and monthly mean variations of SOC (averaged over 2009-2015 period).