| Abstract [eng] |
Air pollution is a leading global risk factor for death. Aerosol particles, especially those smaller than 1 µm (submicrometer), are harmful due to deep penetration and deposition in the the respiratory tract. These particles also influence Earth's climate by scattering or absorbing solar radiation. Understanding aerosol formation, a spontaneous atmospheric process, is crucial for studying their impact on health and climate. This study compares submicron particle distribution and new particle formation in three locations: Vilnius (urban background, Lithuania), Hyltemossa (forest, southern Sweden), and Abisko (subarctic, remote, northern Sweden), providing unique insights for Northern Europe. The aim of this work is to analyse the sub-micrometer aerosol particle size distribution data and its dynamics measured in Vilnius urban background site (Lithuania) and to compare it with data from Swedish remote-rural sites, including the Hyltemossa and Abisko measurement station. In order to achieve this goal the following objectives were formulated: (1) gain insights into instrument performance and data consistency by comparing different aerosol measurement instruments for critical aerosol properties (at Hyltemossa measurement station); (2) identify the formation of new aerosol particles and quantify the frequency and growth rates of new particle formation events measured in different regions during the campaign; (3)analyse and identify the formation influencing factors of new aerosol particles; (4) compare various patterns of submicrometer aerosol particle concentration between measurement sites located in different regions and representing different background (i.e. urban, rural background, remote area). The study of data from the ACTRIS station in Hyltemossa, Sweden, provides insights into aerosol measurement reliability. Addressing discrepancies with closure studies revealed reasonable agreement for used instruments' datasets and significantly enhanced ACTRIS data quality. The study shows the need for multiple instruments, regular calibration, and intercomparison to ensure accuracy and station reliability. In Vilnius, Hyltemossa, and Abisko measurement stations, new particle formation occurred 40-60% of the time during the warmest seasons (March-October in Vilnius and Hyltemossa, June-July in Abisko). NPF was less frequent in Vilnius compared to rural and remote Swedish sites, likely due to urban pollution. However, NPF events were more intense in Vilnius, with median growth rates 1.5 times higher than in Hyltemossa, consistent with literature comparisons. Meteorological factors significantly influence new particle formation. At the Hyltemossa site, solar radiation was higher by 80% on NPF event days, while relative humidity was lower compared with non-event days at all sites. Wind direction and air mass origin exhibit significant correlations with NPF frequency; it decreases with continental air masses and increases with marine air masses in Vilnius and Hyltemossa. Further studies are needed to investigate these influencing factors. The analysis of seasonal behavior demonstrated winter lows and spring peaks in aerosol number concentrations. From March 2022 to February 2023, the average submicron aerosol particle number concentration in Vilnius's urban background was 4560 cm-3, which is lower than in many other European cities. In contrast, measurements from Hyltemossa and Abisko showed lower average concentrations, indicating cleaner environments in these Swedish forest and rural locations compared to the urban background in Vilnius. This study reveals the factors influencing submicrometer aerosol dynamics in urban, remote and sub-arctic forest environments, emphasizing the complexity and importance of aerosol particle formation. |
