Increasing atmospheric dust transport towards the western Mediterranean over 1948–2020
In this study, global reanalysis dataset fields of meteorological parameters (temperature and geopotential height at different atmospheric levels) in the period 1948–2020, were used to characterize the main dynamic and thermodynamic features of African dust outbreaks (ADO) produced over regions of the Iberian Peninsula and the Balearic Islands. The record of ADO previously identified with a tried-and-true procedure in 8 different areas of this domain in the period 2001–2020 and the data sets of dust load contributions estimated for all ADO days in each region, were used to check our results. Thus, we demonstrated that air masses of African origin produced a significant increase in the levels of certain thermodynamic variables (geopotential thickness in the 1000–500 hPa layer (GT), mean potential temperature between 925 and 700 hPa (TPOT), and temperature anomalies at 850 hPa (TANOM)) over the regions of study, especially when particular synoptic-scale atmospheric circulation types (CT) occurred. Moreover, higher levels of the three thermodynamic parameters resulted in events with higher contributions of dust load to the regional background levels of PM10 in all regions. Finally, we obtained a statistically significant upward trend for days under ADO CT and their associated daily mean values of GT, TPOT and TANOM from 1948 to 2020. These results point to an increase in the frequency of air mass transport from North Africa to the western Mediterranean basin and on the intensity of the ADO produced as a consequence of this transport, over 1948–2020.