Environmental Engineering Reference
In-Depth Information
Grass pollen concentration seems to be more difficult to predict than that of
birch pollen. Present system uses the same pollen release model and dynamic
threshold values for birch and grass, but most probably there should be something
different for grasses. Grass pollen concentration is a more local phenomenon,
hence the local and microscale factors are more important, such as a fraction of
grass, local rain showers and micro climate.
Grass pollen season is long, weeks or months, hence a few days of mis-
predicted starting and ending of flowering are not as disturbing as for birch, where
the whole flowering is much shorter. Therefore, the prescribed map of calendar
dates of the start of pollination seems to work surprisingly well, while the end of
the season appeared more problematic, especially in the southern Europe, where
drought can interrupt the flowering. However, in temperate climate (e.g., Moscow,
Fig. 1b
) the whole season can be prescribed reasonably well.
For birch, the Thermal Time-type phenological model predicted starting dates
of flowering in 2008 surprisingly well in most part of Europe, as well as the
ending of the season with typical long tail (e.g.,
Fig. 1a)
.
4. Conclusions
Grass pollen concentrations seem to be more difficult to predict than birch pollen
concentrations. Grass pollen grains is heavier and sources locate near ground.
Thus grass pollen represents smaller area than birch pollen and is more sensitive
to local factors, like fraction of grass, rain showers and micro climate.
Rain and high humidity prevent high pollen concentrations, while high 2 m
temperature correlates well with high pollen counts. Instead effect of wind speed
does not shown in pollen concentration forecasts.
Acknowledgments
The work and the presentation at ITM-2009 have been supported by COST
Action ES0603, ESA-PROMOTE project, and FP-7 project HIALINE. The data have been
provided by the European Aeroallergen Network EAN.
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