In-situ measurements of particulate matter concentration are systematic and with high spatial density in Europe, but very sparse, discontinuous and rarely near-real-time available close of the main dust sources. Satellite products present global coverage. However, they usually integrate the aerosol contents over the vertical column and do not provide information about the dust contents close to the ground.
Since the data sets of weather records have an excellent spatial and temporal coverage, visibility data included in meteorological observations can be used as an alternative way to monitor dust events. Visibility is mainly affected by the presence of aerosol and water in the atmosphere. Therefore, the use of visibility data has to be complemented with information on present weather to discard those cases where visibility is reduced by the presence of hydrometeors (fog, rain, etc.).
The maps published in this page show cases of visibility reduction by sand or dust to less than 5 km reported in METAR or SYNOP bulletins. More than 1,500 stations are checked every 6 hours. Brownish circles indicate stations where 'sand' or 'dust' has been explicitly reported. Triangles indicate stations where the present weather has been reported as 'haze', meaning that the visibility is reduced by particles of unspecified origin.