| Abstract [eng] |
This master's thesis analyses the long-distance transport of birch pollen in Lithuania. The aim of the work is to analyse the potential long-distance transport of birch pollen in Lithuania and to determine the dependence of pollen concentrations caused by long-distance transport on meteorological conditions. To achieve this goal, the following tasks were set: based on the aerobiological situation in the city of Klaipeda from 2005 to 2023, to analyse the mechanism of long-distance transport of birch pollen; to assess the amount of birch pollen in the air due to long-distance transport and analyse cases when large amounts of pollen reached Lithuania due to this transport; to determine the dependence of birch pollen concentration in the air due to long-distance transport on air temperature, precipitation, wind speed, and direction; based on the results, to provide recommendations for pollen monitoring. The study covers the analysis of birch pollen data collected at the aerobiological station in Klaipeda over a 19 year period (2005–2023), focusing on the amount of pollen before and after the pollen season. The data were obtained from the aerobiological station of Vilnius University's Siauliai Academy in Klaipeda. The HYSPLIT model was used to determine the backward trajectories of air masses and model particle dispersion. Spearman's rank correlation coefficient was used to determine the relationship between birch pollen concentration and meteorological parameters, and multiple regression analysis was employed to determine the relationship between daily birch pollen concentration before the pollen season and complex meteorological conditions. The total amount of birch pollen in Klaipeda due to long-distance transport during the period from 2005 to 2023 was 49732 pollen grains/2 hours. Before the start of the birch pollen season, 17,02 pct less pollen was recorded than after the end of the pollen season. It was found that throughout the study period, air masses from European region 1 (Great Britain, Ireland, Denmark, etc.) and European region 4 (Norway, Sweden, Finland, etc.) most frequently reached the Klaipeda aerobiological station. The results indicate that the amounts of birch pollen before the pollen season and after the end of the pollen season are associated with air masses arriving from the same European regions. According to particle dispersion modelling results, most of the birch pollen was likely brought from Northern European countries and Central European countries. Based on the results of single-factor correlation analysis, it can be stated that there is a relationship between average air temperature and birch pollen concentration in the air before the start of the pollen season. Multiple regression results showed that the average air temperature is the most important factor determining the amount of birch pollen due to long-distance transport recorded before the start of the pollen season. |
