A mechanism for long distance transport of Ambrosia pollen from the Pannonian Plain

The pollen grains of ragweed are important aeroallergens that have the potential to be transported long distances through the air. The arrival of ragweed pollen in Nordic countries from the Pannonian Plain can occur when certain conditions are met, which this study aims to describe for the first time. Atmospheric ragweed pollen concentrations were collected at 16 pollen-monitoring sites. Other factors included in the analysis were the overall synoptic weather situation, surface wind speeds, wind direction and temperatures as well as examining regional scale orography and satellite observations. Hot and dry weather in source areas on the Pannonian Plain aid the release of ragweed pollen during the flowering season and result in the deep Planetary Boundary Layers needed to lift the pollen over the Carpathian Mountains to the north. Suitable synoptic conditions are also required for the pollen bearing air masses to move northward. These same conditions produce the jet-effect Kosava and orographic foehn winds that aid the release and dispersal of ragweed pollen and contribute towards its movement into Poland and beyond.