Extremely High Concentrations of Ice Particles in East Asian Dust‐Infused Baroclinic Storm (DIBS) Cirrus Shield: Dominant Role of Dust Ice Nucleation Effect

Abstract

Cirrus clouds have a significant impact on the Earth's radiative budget and climate because of their extensive global coverage. Occurred high in the upper troposphere at altitudes of 8-17 km, cirrus clouds consist exclusively of ice particles (Lynch & Sassen, 2002). Ice crystals form via homogeneous and heterogeneous ice nucleation. Homogeneous nucleation involves supercooled liquid droplets and aerosol haze particle freezing at temperatures below −38°C. When ice nucleating particles (INPs) are present, heterogeneous nucleation can occur at a less supersaturation or supercooling than homogeneous nucleation (Khain & Pinsky, 2018). Heterogeneous ice nucleation includes several pathways, among which are deposition nucleation, immersion freezing, contact freezing and condensation freezing (Vali et al., 2015).

Effects of Pollen on Hydrometeors and Precipitation in a Convective System

“…The first revision for cirrus formation is to replace the Cooper (1986) scheme that simulates deposition freezing in original MMS with a mechanism developed by Ullrich et al. (2017), hereafter U17, to simulate deposition freezing for dust and soot, which has been implemented and evaluated by previous studies (e.g., Marinou et al., 2019; Y. Zeng et al., 2023). Modeled interstitial dust and element carbon (soot) in Aitken and accumulation modes are included in U17 to represent heterogeneous freezing.…”

“…At higher altitudes which are colder and drier, deposition (not considered for mixed phase clouds) becomes a more important heterogeneous nucleation mechanism. The first revision for cirrus formation is to replace the Cooper (1986) scheme that simulates deposition freezing in original MMS with a mechanism developed by Ullrich et al (2017), hereafter U17, to simulate deposition freezing for dust and soot, which has been implemented and evaluated by previous studies (e.g., Marinou et al, 2019;Y. Zeng et al, 2023).…”

“…In previous studies, the impacts of INP on clouds have been investigated, considering sources such as dust, black carbon, and sea salt (McGraw et al, 2020;Shi et al, 2022;X. Zeng & Li, 2022;Y. Zeng et al, 2023).…”

“…Variations in INP concentration have been found to alter cloud ice content and ice particle radius, thereby impacting atmospheric radiation (X. Zeng et al., 2009a, 2009b; B. Zhao et al., 2018). In previous studies, the impacts of INP on clouds have been investigated, considering sources such as dust, black carbon, and sea salt (McGraw et al., 2020; Shi et al., 2022; X. Zeng & Li, 2022; Y. Zeng et al., 2023). In comparison to other INPs (e.g., dust, black carbon, soot, sea salt, and organic aerosol), pollen and other PBAPs can facilitate ice nucleation at warmer temperatures (up to −5°C) (e.g., Kanji et al., 2017; Möhler et al., 2007; Patade et al., 2021; Schnell & Vali, 1973; Testa et al., 2021), potentially acting as an important INP source in PBAP abundant environments such as forest ecosystems (Prenni et al., 2009; Testa et al., 2021; Tobo et al., 2013).…”