On 21–23 February 2021, dust from a sand and dust storm (SDS) in northern Africa was transported to Finland, north of 60°N. The episode was predicted 5 days in advance by the Finnish Meteorological Institute (FMI) global operational SILAM forecast (silam.fmi.fi), and its key features were confirmed and detailed by a retrospective analysis. SILAM is among the dust forecast models included in the Word Meteorological Organization Sand and Dust Storm Warning Advisory and Assessment System WMO SDS-WAS.

The coloured snow caused people to contact FMI asking what is happening. FMI launched a citizen science campaign on Saharan dust in Finland with the help of social media. People were asked to report their observations and to collect dust-containing snow and to extract the dust according to the guidelines. The campaign gained wide national interest in television, radio, newspapers and social media, and resulted in success in receiving citizen samples from 525 locations.

This publication contains multiple modelling and particle analysis results of the event. For example, both the modelling and the particle magnetic properties confirmed that dust came from a wide Sahara and Sahel area, from 5000 km away. Particle size distributions, color and minerals of selected samples provided further information. Based on our work, we recommend to extract dust from snow using evaporation under 75oC to preserve the magnetic properties of the particles.


Meinander, O., Kouznetsov, R., Uppstu, A. et al. African dust transport and deposition modelling verified through a citizen science campaign in Finland. Sci Rep 13, 21379 (2023). https://doi.org/10.1038/s41598-023-46321-7