40-years of Saharan dust events in the Carpathian Basin: background, frequency, intensity, changing patterns

Saharan dust events were investigated in the Carpathian Basin (Central Europe) for the period between 1979 and 2018 by using various satellite (TOMS and OMI Aerosol Index; MODIS AOD) and numerical forecast (Barcelona Supercomputing Centre’s DREAM, NMMB/BSC-Dust-model and SKIRON) products and modelled deposition of NASA’s Modern-Era Retrospective analysis for Research and Applications, Version 2. The identified 218 episodes were classified into three characteristic clusters based on synoptic background. 700 hPa geopotential height, wind vectors and meridional flow patterns, as well as backward trajectories of the episodes determined the classification.

Interannual variability of dust activity was remarkable, while seasonal frequencies of the episodes revealed clear spatiotemporal patterns with spring (40.2%) and summer (31.6%) maxima of the events. Mean values of dust deposition showed springtime maxima (44.1%) and dominance of wet deposition (77-93%), while amount of deposited dust material in the other seasons were quite similar, indicating the governing role of local weather conditions (e.g., precipitation patterns). Average warm advection of the episodes was 3.5°C (with spring minima, due to the more rain), but the decadal surface air temperature anomalies showed a general increasing trend.

Recently, a few more intense wintertime dust deposition events indicated changes in the deterministic atmospheric flow system. Seasonal and decadal zonal mean surface air temperature anomalies of dusty days showed clearly the increased warming of high latitudes during the last few winter episodes. The enhanced meridionality of (dust transporting) winds was also observable in the number of days with 15< m/s meridional wind component (at 700 hPa). Warmer Arctic region and more meandering air flow patterns could be responsible for these unusual dust episodes in the recent years.

Support of the National Research, Development and Innovation Office NKFIH KH130337 and NKFIH K120213 are gratefully acknowledged.