8.1880, 120 years ago. The frequency of storms was studied because the number of extreme weather events is generally expected to increase with climate change. In this case nutrient deposition may increase if emissions do not decline. But, over the Baltic Sea, this analysis did not show any increase in storm frequency. Although the HIRLAM data period covered too few years for any conclusion to be drawn, no trend could be detected also in the measurement station data. The hypothesis of increasing extreme weather event frequency may not be valid either: according
to Zahn & Storch (2010), in warmer climate conditions the ERK inhibition frequency of North Atlantic polar lows will decrease and their latitude will be shifted further north because stability over the Atlantic Ocean will increase. The latitude of a cyclone track does not necessarily determine the amount of deposition. Even if the cyclone crosses the central BS Proper, it still depends on the stability of the atmospheric boundary layer over the pollutant emission areas whether contaminants are accumulated there into the air or not. On the other hand, if the cyclone were to follow a more northerly route along the Norwegian coast, there might still be a wet episode over the BS connected with fronts, or a dry episode event caused by turbulence over the water,
if a simultaneous favourable flow from intensive emission areas occurred. Areas of rain associated with cyclonic activities can be located Natural Product Library order quite far from the cyclone centre. The influence of weather has to be analysed by studying each episode case-by-case, using backward simulations and by checking weather conditions along the whole transport path: local instantaneous conditions over water bodies do not explain a great deal. I would like to thank Pirkko Karlsson and Pentti Pirinen for retrieving the meteorological parameters from the FMI data base, Ari Seinä
and Jouni Dimethyl sulfoxide Vainio for the Baltic Sea ice cover data, Robin King for suggesting language corrections, and both anonymous referees for their valuable comments.The support of the Interreg IVA programme (SNOOP, SFE16) is gratefully acknowledged. “
“The Baltic Sea is considered to be a eutrophic sea, although the seasonal maximum of the nutrient concentrations in the central Baltic are much lower than in high latitude oceanic regions. Current mean nitrate and phosphate concentrations in the Baltic Proper amount to about 3–4 μmol dm−3 and 0.4–0.6 μmol dm−3 respectively, and are lower by a factor of 2–3 than those in the North Atlantic. Nonetheless, the use of the term ‘eutrophication’ for the Baltic Sea nutrient conditions is adequate in the historical perspective, because nutrient loads and productivity increased by a factor of about 3 during the last century as a result of anthropogenic activities ( Schneider & Kuss 2004, Savchuk et al. 2008).