Atmospheric modelling of maize pollen dispersal at regional scale
Résumé
The possibility for maize pollen to contaminate plants at very long distances has been recently demonstrated from (i) airborne measurements of pollen concentration and viability in the atmospheric boundary layer, (ii) chamber measurements of pollen viability and (iii) observations of fecundations in isolated plots of white-kernel maize. In order to better understand long-range dispersal of maize pollen we use the non-hydrostatic mesoscale Meso-NH model, modified so as to introduce source terms for pollen emission, conservation equations for pollen concentration and moisture as well as a deposition velocity. Using GIS-based landuse maps featuring all maize fields previously identified from satellite data, a series of simulations have been performed over South-West France down to a 2-km horizontal resolution. The model allows the regional pollen plume to be tracked during the day and deposition maps of viable pollen to be produced over dozens of km. Vertical and horizontal variations in simulated pollen concentration agree well with measured airborne data all along the day. On typical convective days calculated pollen deposition at remote distances from the source fields is shown to be compatible with the regional “background” contamination producing the fattailed dispersal functions observed in the field. The present model can be used as a basis for future operational pollen forecast tools.