Desert in the snow around Sonnblick
Eroded Saharan dust (SD) is episodically transported over thousands of kilometers with synoptic wind patterns towards Europe and reaches Austria several days per year. The SD is removed from the atmosphere via dry or wet deposition processes and thereby significantly changing the chemical composition of the precipitation or the affected environment. On the one hand, SD serves a high ionic input leading to an increase of many ionic species especially Ca2+, Mg2+ or SO42-. On the other hand, SD provides a high alkaline input neutralizing acidic components and causing the pH to increase. Both effects can influence the prevailing ecological system.
Based on the pH and the Ca2+ concentrations of snow samples from Goldbergkees collected annualy at the end of the winter accumulation period, SD affected snow layers (SDLs) within the 30-year long snow chemistry data set were identified. Using a pH>5.6 and Ca2+>10µeq/l as criteria almost every year SDLs could be found (compare Table 1) whereas their contribution to the mean annual ion deposition (compare Figure 1) is only relevant for single years with either few but strong single events (e.g. 2016) or a higher number of weak events (e.g. 1996).
The long term trends of ion deposition are not affected by the deposition of SD.
Results of this study are published here.
Interannual variability of the overall annual deposition load (OAD) separated in the contribution of SDLs in gray and non-SDLs in black.
Overview and seasonality of the number of identified SDLs within snow pack data (1987–2017, missing data for 1988-1990)