A 43 years-long European pollen reanalysis for alder, birch, and olive

Airborne pollen released by plants during their flowering season can cause significant allergic symptoms impairing public health, especially if accompanied with air pollutants and/or weather phenomena (e.g., high temperature). Apart from the public health-related motivation, information on pollen in the air can be useful to monitor biodiversity, follow species migration, habitat degradation, etc. Systematic knowledge about continental-scale pollen distribution patterns is hard to obtain due to tedious manual observation methods used through decades and limited modelling experience and maturity level.

The European Pollen Reanalysis v.1.1 (EPR) is the first 43 year-long reanalysis of pollen seasons for three major allergenic tree genera in Europe: alder (Alnus), birch (Betula), and olive (Olea). The EPR has been created by the atmospheric composition model SILAM driven by the European meteorological reanalysis ERA5. SILAM predicted a Europe-wide dispersion pollen for 1980–2022. For each year, an extended 4-dimensional variational data assimilation was applied assimilating in-situ observations of aerobiological networks of 34 European countries. The assimilated variable was the total seasonal emission of pollen grains. Therefore, the EPR assimilation constitutes an inverse dispersion problem solution realized as an annual correction factor to the mean pollen production. The EPR is positioned as an input for health- and climate- related studies, biodiversity monitoring, etc.