(52g) The Influence of Atmospheric ‘Blocking Signature’ on Urban Particulate Matter (PM2.5 and PM10) and Trace Gases Characteristics of the City: Nur-Sultan, Central Kazakhstan

Nur-Sultan (formerly known as Astana) is a planned capital city of Kazakhstan, it has now turned into one of the cities of rapid urbanization and industrial development over the past two decades. Also, in terms of the region's climate, it is one of the coldest capitals in the world with a sharply continental climate. Due to cold and long winters (peak temperatures as low as -50°C) and dry summer periods (peak temperatures of up to 40°C), air pollutants levels are very sensitive to atmospheric stability and meteorological parameters. In wintertime, against the background of low temperatures in Nur-Sultan, calm and cloudless weather is often established due to the dominance of the Siberian anticyclone in the territory. Changes in the level of air pollution in a city as a whole are determined by many factors, including anthropogenic and natural sources of pollution, atmospheric circulation patterns, the composition of the atmosphere, meteorological conditions, and meso- and microclimatic features of the urban environment. In this research, the 15 minute concentrations of air pollutants, including particulate matter (TSP, PM10, PM2.5, PM1), nitrogen dioxide (NO2), nitrogen oxide (NO), ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2), volatile organic compounds (VOC), carbon dioxide (CO2), and meteorological parameters such as rainfall, temperature, humidity, pressure, wind speed were used for 2020 heating period from the AQM 65 monitoring station located in the city. The atmospheric depth layer heights and 500 hPa and 850 hPa geopotential maps and atmospheric stability time-series data (boundary layer depth (BL), vertical mixing coefficient (VM), horizontal mixing coefficient (HM) and friction velocity (FV)) were extracted using the Global Data Assimilation System (GDAS) and the NCAR Reanalysis datasets. In this study, potential episodic periods in 2020 were identified, they were further investigated to assess their relationship with blocking anticyclones by checking their pollution characteristics, local meteorological characteristics, changes in meridional gradients on geopotential altitude maps of 500 hPa and 850 hPa. We find out that, air pollution levels in the city are highly influenced by regional meteorological fluctuations, atmospheric circulation patterns and the formation of extensive stationary anticyclones with atmospheric blocking effects. The results confirm the conclusion that high pressure conditions and climatic characteristics of the city are significant factors in the accumulation of episodic periods of air pollutants in the atmosphere, and their concentration remains at a higher level for a long time, especially during periods of stagnation of the anticyclone.