Meteorological and climatological conditions supportive for windblown dust formation in Poland

Abstract

Windblown dust is considered a type of severe weather phenomena, causing low horizontal visibility, high particulate matter concentrations and economic loss. Although dust events mostly occur in arid and semiarid climates, they are also being reported in Poland during dry spells. Currently there are no comprehensive studies releted to windblown dust climatology of Poland, despite their abundance in the recent years. In order to identify significant windblown dust events in Poland, compiled data from meteorological stations, air quality stations and media/social media platforms was used. Hourly observations from 50 Polish meteorological stations were obtained in order to gather all windblown dust related reports. Hourly mean PM₁₀ concentrations were obtained in order to estimate the impact of windblown dust on air quality as well as to identify cases away from meteorological stations. Lastly, media and social media reports, depicting intense windblown dust, were included in the study in order to make the database more detailed. A total of 65 days with a windblown dust were identified for a period between 2001 and 2022. Each case was examined based on a type of a meteorological disturbance causing it (synoptic or convective).

Meteorological conditions present during windblown dust cases, including near-surface relative humidity, wind speed and visibility were also analyzed along with surface soil moisture and Standarized Precipitation Evapotranspiration Index (SPEI). Additionaly, atmospheric soundings and vertical tropospheric relative humidity profiles were simulated for convective windblown dust cases, based on ECMWF ERA5 Reanalysis. It was found that central and western regions of Poland are most prone to windblown dust, with April being by far the most active month for dust activity. Significant differences were also noted between the intensity of recorded windblown dust occurrences, with most cases being local and lasting less than 1 h to some covering large area of a Country and lasting for over 10 h. Recorded convective windblown dust most commonly formed as a result of thunderstorm's outflow, connected to cold fronts and low tropospheric convergence zones. High Lifted Condensation Level and low humidity in the lower troposphere strongly supported this type of events.