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Title: Minimalist Model of Ice Microphysics in Mixed-phase Stratiform Clouds

The question of whether persistent ice crystal precipitation from super cooled layer clouds can be explained by time-dependent, stochastic ice nucleation is explored using an approximate, analytical model, and a large-eddy simulation (LES) cloud model. The updraft velocity in the cloud defines an accumulation zone, where small ice particles cannot fall out until they are large enough, which will increase the residence time of ice particles in the cloud. Ice particles reach a quasi-steady state between growth by vapor deposition and fall speed at cloud base. The analytical model predicts that ice water content (wi) has a 2.5 power law relationship with ice number concentration ni. wi and ni from a LES cloud model with stochastic ice nucleation also confirm the 2.5 power law relationship. The prefactor of the power law is proportional to the ice nucleation rate, and therefore provides a quantitative link to observations of ice microphysical properties.
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Journal Article
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Journal Name: Geophysical Research Letters, 40(14):3756-3760
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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Country of Publication:
United States
model; ice; microphysics; mixed-phase; stratiform; clouds