Climatology of convective dust storms in Poland

Dust storms are an unusual and understudied type of severe weather phenomena in Europe, causing low horizontal visibility, hazardous to human health particulate matter concentrations and economic losses. Despite occurring mostly in arid and semiarid climates, dust storms are also being reported occasionally in Poland during severe drought periods. Regions most prone to dust storms in Poland include Greater Poland, Masovian, Kuyavian-Pomeranian and West Pomeranian Voivodeships. A significant horizontal gradient of sea level pressure, as well as convective phenomena, are considered the main causees of dust storms in Poland. Apart from strong wind, low near-surface level relative humidity, low soil humidity and negative Standarised Precipitation-Evaporation Index (SPEI) values also support dust storms' development. Based on a comparison between particulate matter concentration data, obtained from air quality measurement stations and meteorological data obtained from synoptic stations, dozen of convective dust storm days were identified in the Polish warm period (April-September) between 2003 and 2020. Recorded dust events formed most commonly as a cause of thunderstorm's outflow, connected to cold fronts and low tropospheric convergence zones. ERA5 reanalysis combined with atmospheric soundings data were used  in order to determine the environment supportive for convective systems likely to produce a dust storm.  High Lifted Condensation Level values and low humidity in a lower troposphere strongly supported this type of events.