Particle Size Analysis of African Dust Haze over the Last 20 Years: A Focus on the Extreme Event of June 2020

Lovely Euphrasie-Clotilde,Thomas Plocoste,France-Nor Brute

doi:10.3390/atmos12040502

Lovely Euphrasie-Clotilde, Thomas Plocoste + Show 1 more

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https://doi.org/10.3390/atmos12040502

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Journal: Atmosphere	Publication Date: Apr 15, 2021
Citations: 16	License type: CC BY 4.0

Affiliation: Géosciences Montpellier

Abstract

Over the last decades, the impact of mineral dust from African deserts on human health and climate has been of great interest to the scientific community. In this paper, the climatological analysis of dusty events of the past 20 years in the Caribbean area has been performed using a particulate approach. The focus is made on June 2020 extreme event dubbed “Godzilla”. To carry out this study, different types of data were used (ground-based, satellites, model, and soundings) on several sites in the Caribbean islands. First, the magnitude of June 2020 event was clearly highlighted using satellite imagery. During the peak of this event, the value of particulate matter with an aerodynamic diameter of less than 10 μμm (PM10) reached a value 9 times greater than the threshold recommended by the World Health Organization in one day. Thereafter, the PM10, the aerosol optical depth, and the volume particle size distribution analyses exhibited their maximum values for June 2020. We also highlighted the exceptional characteristics of the Saharan air layer in terms of thickness and wind speed for this period. Finally, our results showed that the more the proportion of particulate matter with an aerodynamic diameter of less than 2.5 μμm (PM2.5) in PM10 increases, the more the influence of sea salt aerosols is significant.

Highlights

In the literature, it is well known that Africa is the world’s largest source of mineral dust [1,2]
The monthly behavior of mineral aerosols transport to the Caribbean islands over the last two decades shows that (i) the low dust season is from September to May (Figure 2a–c); this period coincides to the high dust season of the Northern part of South
This climatological analysis of the dusty events in the Caribbean area over the last 20 years highlighted the extreme intensity of the episode in June 2020 dubbed

Summary

Introduction

It is well known that Africa is the world’s largest source of mineral dust [1,2]. Millions of tons of mineral dust are transported from the African continent towards the Atlantic ocean in the Saharan Air Layer (SAL), i.e., dry and stable air masses confined between two inversion layers at an altitude of 1 to 5 km [3,4]. Dust particles play a significant role in the air quality and climate system [5,6]. DomínguezRodríguez et al [11] showed that an inhalation of desert dust may result in a 2% increase in cardiovascular mortality risk. Dust particles influence Earth’s radiation budget directly by scattering, absorbing, and re-emitting radiation, and indirectly by impacting the atmospheric dynamics [12,13,14,15].

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