亚欧大陆科学资源管理

There is growing scientific interest in the impact of atmospheric circulation on regional air quality; however, it ispoorly studied in Central Asia. This study is the first assessment of the evidence-based relations between airpollution episodes and the elementary circulation mechanisms (ECMs, by the classification from Dzerdzeevskiiet al.) with atmospheric blocking process effects on an urban atmosphere over the geographical center of theEurasian continent. The capital city of Kazakhstan, Nur-Sultan, is selected as the study location since it is locatedin the north of the Kazakh Uplands in a dry steppe zone. First, an episode identification procedure using multiplestations and multiple-pollutant time series data is proposed. After the identification of the aggregated pollutantepisodes during the heating and non-heating periods in 2017, their relations with blocking anticyclones andcyclones are further investigated by checking the reversal of meridional gradients in the 500 hPa and 850 hPageopotential height (GPH) maps. In total, 12 and 9 pollution episodes lasting an average of 5 days were identified in heating and non-heating periods, respectively. Following the calendar of continuous ECM changes, thetype of ECM is determined for each episode, and then, the types of ECMs with atmospheric circulation andtrajectory characteristics corresponding to the episodes were analyzed in detail. The findings suggest that i)regional and local air pollution levels on the Eurasian Steppes are actively controlled by regional meteorologicalvariations, ii) the northern streams of cold Arctic air spread to the region and Siberian anticyclone reaches inwinter, leading to extreme negative air temperature anomalies that contribute to the further cooling of the Arcticair and formation of extensive stationary anticyclones with blocking effects over the region, iii) a cold seasoncirculation type, ECM 13w, was one of the most dominant ECMs with approximately 23% annual prevalencecausing 30% of all the episodes, iv) ECMs 11a, 5a, and 5b were also associated with much higher pollution levels(up to 4-fold increases over the annual average), but they had lower prevalences (up to 5%). As a result, it wasdemonstrated that the regional climate conditions with particular ECMs regulate the ventilation characteristicsof the atmosphere over the study area, and local air pollution concentrations increase to extreme levels andremain there longer, particularly during stationary anticyclone periods.