Hail suppression effectiveness for different cloud condensation nucleus (CCN) populations in continental and maritime environments

• Published in: Aerosol science and technology Vol. 57; no. 7; pp. 645 - 664
• Main Author: Kovačević, Nemanja
• Format: Journal Article
• Language: English
• Published: New York Taylor & Francis 03-07-2023; Taylor & Francis Ltd
• Subjects: Aerosol research; Cloud condensation nuclei; Cloud droplet concentration; Cloud droplets; Cloud seeding; Clouds; Condensation; Condensation nuclei; Effectiveness; Hail; Hail damage; Hail suppression; Hailstorm effects; Mathematical models; Nicole Riemer; Numerical simulations; Parameters; Rain; Rainfall; Solubility; Spatial distribution
• ISSN: 0278-6826; 1521-7388
• DOI: 10.1080/02786826.2023.2208182

A cloud model was used to investigate the indirect influence of the parameters of cloud condensation nuclei (CCN) on hail suppression at the surface. The values of three parameters were changed: the mean radius (r
m
) and standard deviation of the CCN spectrum (lnσ) and their solubility in water (ε
m
), especially under continental and maritime conditions. A sensitivity study compared the numerical simulations for unseeded and seeded cases using the two-moment bulk microphysical scheme. Different combinations of the three aforementioned parameters were tested for continental and maritime environments. The spatial distribution of surface precipitation and the surface amounts of rain and hail for unseeded and seeded cases were analyzed. Continental environments characterized by an extremely small solubility of CCN in water were not suitable for hail suppression. Hail suppression was favorable (-26.23% and −8.66%) for continental conditions characterized by typical values of cloud droplet number concentrations (100-1000 cm
−3
). A very polluted continental environment showed the greatest reduction in surface hail after cloud seeding (-84.67%). For maritime environments, a rain enhancement was observed in all seeded experiments. The hail prevention effectiveness was discouraging (136.26%) under certain maritime conditions (ε
m
= 1; lnσ = 1; r
m
= 0.1 µm). An extreme maritime environment led to a very negligible hail suppression effectiveness (-0.28%). It can be concluded that different spectra of CCN strongly impact the accumulations of surface rain and hail, as well as the operational decisions on whether to conduct cloud seeding to suppress damaging hail on the ground.
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