MACC regional multi-model ensemble simulations of birch pollen dispersion in Europe

This is the authors' abstract. We don't add key points for this paper.

The paper presents the first-ever ensemble modelling experiment for the birch pollen in Europe. The 7-models strong European ensemble of MACC-ENS, tested in trial simulations over the season of 2010, has been run through the season of 2013. The simulations have been compared with observations in 11 countries, members of European Aeroallergen Network, for both individual models and the ensemble mean and median. It is shown that the models successfully reproduced the timing of the very late season of 2013, generally being within a couple of days from the observed season start. End of the season was generally predicted later than observed, for 5 days or more, which is a known feature of the source term used in the study. Absolute pollen concentrations during the season were somewhat under-estimated in the southern part of the birch habitation area. In the northern part of Europe, a record-low pollen season was strongly over-estimated by all models. Median of the multi-model ensemble demonstrated robust performance, successfully eliminating the impact of outliers, which was particularly useful since for most of models this was the first experience of pollen forecasting.