July 31, 2023 Dataset Open Access

Variability of dust composition in the tropical North Atlantic - Saharan Air Layer (Metadata RADIATE TA Proposal 22003016-ST)

Chiari, Massimo; Nava, Silvia; Rodríguez, Sergio

Proposal title "Variability of dust composition in the tropical North Atlantic - Saharan Air Layer". Measurements carried out at the external beam set-up for atmospheric aerosol analysis of the INFN LABEC accelerator laboratory, on 24 October 2022 and from 5 till 7 December 2022. Hands-off mode.

The objective of the experiment is to study the variability of aerosols and dust composition in tropical Saharan Air Layer, i.e. the dusty airstream that spreads from North Africa, across the tropical North Atlantic to inner North America. Dust is a mixing of tens of minerals, each presenting physical and chemical properties which modulate dust impacts, e.g. feldspars are active ice nuclei, hematite absorb UV radiation, carbonates neutralize acid pollutants, whereas iron bearing clays and oxides provide iron to ecosystems.

In this experiment two types of aerosols samples collected from June to August 2022 in Cape Verde, at 1450 meters altitude in the island of Santo Antão, were analysed: (1) 1200 samples of 1 hour resolution collected with the STRAS (Size and Time Resolved Aerosol Sampler) sampler designed by INFN, and (2) 105 samples of PM10 and PM2.5 collected with a daily basis (10h sampling) on 47 mm teflon and Whatman41 membranes using low volume samplers (Gemini DadoLab). 

The objective is to study the variability of dust composition in the core path of the Saharan Air Layer in the tropical North Atlantic and to identify the source regions and hot spots enriched in key elements. Samples were analysed by PIXE with a 3 MeV proton beam (energy on target) to determine the concentrations of major (Si, Al, Ca, Fe, Na, Cl, K…) and trace elements (Mn, Mg, Sr, S……) of dust.