Chemical characterization of PM2.5 from region highly impacted by hailstorms in South America

Lin

et al. 2023

Preprint

Abstract. Insoluble particles affect weather and climate indirectly by heterogeneous freezing process. Current weather and climate models have large uncertainty in freezing process simulation due to little regarding species and number concentration of heterogeneous ice-nucleating particles, mainly insoluble particles. Here, for the first time, size distribution and species of insoluble particles are analyzed in 30 shells of 12 hailstones in China, using scanning electron microscopy and energy dispersive X-ray spectrometry. Total 289,461 insoluble particles are detected and grouped into 3 species: organics, dust, and bioprotein by machine learning methods. The size distribution of insoluble particles of each species vary greatly in different hailstorms but little in shells. Further, classic size distribution modes of organics and dust were performed as logarithmic normal distributions, which may be adapted in future weather and climate models though uncertainty still exists. Our finding suggests that physical properties of aerosols should be considered in model simulation on ice freezing process.

Section: Sample Representativenesssupporting

confidence: 88%

Analysis of insoluble particles in hailstones in China

Lin

et al. 2023

Preprint

“…The region, which belongs to the Upper Paraná River Basin, is characterised by an agricultural landscape [24] and is among the top regions with worst storms in the world [25,26]. Due to the main synoptical system that occurs there, especially because it is the gateway to the Mesoscale Convective Systems and the Low-Level Subtropical Jet [27][28][29] for Brazil and South America, this region has received significant attention from the scientific community in the past few years [30][31][32].…”

Section: Area Of Studymentioning

confidence: 99%

“…Since soil and plants are recognised as sources of PBAPs [17,43], there is also a local contribution of such sources to the microbial loading of the hailstones as well. Beal et al (2022) [32] found through the chemical analysis of fine particles that soil and agricultural activities in the region where the hailstones were collected are the main sources of PM 2.5 . Moreover, the presence of cultivable bacteria (i.e., Bacillus and Methylobacterium) is consistent with a soil and plant-surface origin from the local region and from long-range transport from air masses coming from northern region of Brazil as well.…”

Section: Hysplit Modelling and Microbial Load Of Hailstonesmentioning

confidence: 99%

Biological Characterisation of Hailstones from Two Storms in South Brazil

Mantoani,

Quintino,

Emygdio

et al. 2023

Aerobiology

Although studies focusing on the physicochemical properties of aerosols/clouds have not been performed extensively, even less attention has been given to hailstones and their biological composition. Here, we present the results of the physical and microbiological characterisation of 20 hailstones collected in Southern Brazil originating from two storms. Nearly half of the hailstones (9 out of 20, or 45%) did not contain any cultivable bacteria or fungi. A total of 18 bacterial species were found in hailstones from both storms, and the genus Bacillus was found in 5 out of the 11 hailstones, with Bacillus cereus being the most frequent bacterial species. Fungi, on the other hand, were only present in four hailstones derived from a single storm, with three fungal species identified and Epicoccum nigrum being the most frequent fungal species. HYSPLIT modelling indicated the different flow of air masses from the Amazon and Pacific Ocean that contributed to the loading of microorganisms found in the clouds at the time of the two storms. Our findings suggest that ca. 50% of hailstones have cultivable bacterial or fungal species, which came mainly from the local landscape with intrusions of air masses derived from the Amazon and the Pacific Ocean.

J. South. Hemisph. Earth Syst. Sci.

Bulk cloud microphysical properties as seen from numerical simulation and remote sensing products: case study of a hailstorm event over the La Plata Basin

Vara-Vela,

Machado Crespo,

Vendrasco

et al. 2024

Hailstorms develop over the La Plata Basin, in south-eastern South America, more often during later winter and early austral spring, between September and October. These systems have significant socioeconomic impacts over the region. Thus, a better understanding of how atmospheric drivers modulate the formation of hailstorms is important to improve the forecast of such phenomena. In this study, we selected a hailstorm event observed over the eastern La Plata Basin during 14–15 July 2016 to evaluate the performance of the Brazilian developments on the Regional Atmospheric Modelling System (BRAMS) model. The ability of the model in simulating cloud microphysical properties was evaluated by comparing simulations driven by different global forcings against in situ and remote sensing observations. The model results showed good skill in capturing the basic characteristics of the thunderstorm, particularly in terms of the spatial distribution of hydrometeors. The simulated spatial distribution of hail covers locations where hail fall was reported. The BRAMS simulations suggest that, despite relatively low values of the convective available potential energy (CAPE) (700–1000 J kg−1), environments with strong 0–8-km bulk shear (60–70 kt, ~30.9–36.0 m s–1) can promote the formation of ice clouds and hail fall over the eastern La Plata Basin. To be more conclusive, however, further research is needed to understand how different combinations of CAPE and shear affect hail formation over the region.