by Kornel Kollath and Maria Putsay (Hungarian Meteorological Service), Niels Hansen (Danish Meteorological Institute), Vesa Nietosvaara (Finnish Meteorological Institute), Jochen Kerkmann, Cecilie Wettre and Theo Steenbergen (EUMETSAT)Jump to images
For several weeks in April and May 2006, Finland and many other ountries in Europe experienced extremely high aerosol concentrations. As reported by the Finnish Meteorological Service, in Helsinki there was a long period of bad air quality in the southern and eastern parts of the country. The haze could actually be seen well from the ground, or even better from aircraft when looking in the direction of the sun. Also the Baltic States, Poland, the Czech Republic, Slovakia, Hungary, Germany and other countries reported high aerosol concentrations with low visibility.
The reason for the high aerosol load was not only the numerous grass and forest fires in Western Russia (bringing up lots of aerosol and smoke into the air) but also the high concentrations of pollen in the air. After a long and cold winter in Europe, a sunny, summer-like beginning of May with little or no rain favoured a massive release of pollen grains over a period of just a few days, nearly simultaneously in all European countries. In Denmark new record counts were made for birch pollen at both counting stations: in the capital Copenhagen every cubic meter of air contained on average 4.381 birch pollen. That surpasses the 13 year old record of 3.899 (the Danish Meteorological Institute and the Danish Asthma and Allergic Society have been counting pollen in Copenhagen since 1977). Also adding to the trauma of allergy sufferers in Western Europe was a consistent easterly wind bringing birch pollen all the way from Russia, the Baltic States and Sweden. In Great Britain, a notably increased amount of aerosol from pollen transported from the continent was observed on the east coast, adding to the pollen already produced in abundance by local birch trees.
When looking at the Meteosat HRV images in the early morning (see images below), one can see the extremely hazy, smoke/pollen-loaded air over large parts of Europe (in particular Central, Northern and Eastern Europe). The animation from 4 May (see link under "See also") shows the smoke from the numerous fires in Russia. On 5-6 May the smoke plume, following the easterly wind, reached large parts of Central Europe and started to be blown out over the North Sea and the Atlantic. Finally, on 9 May, still pushed by easterly winds, the pollen/smoke plume can be seen south of Iceland heading towards Greenland and Canada.
Another interesting feature in the images from 9 May is an isolated area of low-level clouds the size of Iceland, over the Atlantic/North Sea. This cloud system was formed two days earlier close to the Norwegian coast. Most probably it represents a fog/low stratus area, drifting westwards in the "off-shore" easterly wind, but the preservation of its shape over such a long time is rather special (normally such cloud fields are "eaten up" from the sides inwards). One possible explanation for the preservation of its shape could be the continental (polluted) character of this cloud, as indicated by the small droplet size and the high reflectivity in the IR3.9r channel (see RGB composite VIS0.8, IR3.9r, IR10.8, 429 KB).
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