Outi Meinander, Finnish Meteorological Institute (IBA-ILMA-project) "Saharan dust on snow and atmosphere in Finland? Citizen observations can help researchers – how to make the observations and where to report?"
Long-range transported mineral dust has a wide range of direct and indirect effects as a climate-forcer, pollutant and nutrient. Only two cases of Saharan dust deposition on snow, in northern Finland in 1991, and in southern Finland in 2021 are known to be reported. In 2021, an unofficial world record of 525 citizen science observations were gained in FMI’s citizen science initiative. Based on these results, new instructions on citizen observations of Saharan dust on snow are given here, including how to make them and where to report.
In a recent paper, the first systematic long-term data for dust storm events from lower latitudes reaching the Finnish atmosphere was presented, based on the MERRA-2 satellite data, meteorological observations, and modelling results. In total, 86 long-range dust transport events were identified between 1980 and 2022, when air masses loaded with dust reached Finland. Based on backward-trajectories different sources were identified: 59 were Saharan, 22 were Aral-Caspian, and five were associated with Middle Eastern source areas. There is a clear maximum of dust events in spring (60%), followed by summer and autumn (where 10 of the 11 autumn episodes were from the Sahara). However, the number and proportion of scarce winter events have more than doubled since 2010 compared to the preceding 30 years. IBA-ILMA project, which will include SILAM modelling, is expected to give an update to these first estimates.
References:
Meinander, O., Alvarez Piedehierro, A., Kouznetsov, R., Rontu, L., Welti, A., Kaakinen, A., Heikkinen, E., and Laaksonen, A.: Saharan dust transported and deposited in Finland on 23 February 2021, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4818, https://doi.org/10.5194/egusphere-egu22-4818, 2022.
Meinander, O., Kouznetsov, R., Uppstu A., Sofiev M., Kaakinen A., Salminen J., Rontu L., Welti A., Francis D., Piedehierro A.A., Heikkilä, P., Heikkinen E., Laaksonen A. African dust transport and deposition modelling verified through a citizen science campaign in Finland, manuscript in review, 2023. Varga G, Meinander O, Rostási Á, Dagsson-Waldhauserova P, Csávics A, Gresina F. Saharan, Aral-Caspian and Middle East dust travels to Finland (1980-2022). Environ Int. 2023 Oct;180:108243. doi: 10.1016/j.envint.2023.108243. Epub 2023 Sep 29. PMID: 37804716, 2023.