Mixed-phase direct numerical simulation: ice growth in cloud-top generating cells
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Published:2023-05-09
Issue:9
Volume:23
Page:5217-5231
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ISSN:1680-7324
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Container-title:Atmospheric Chemistry and Physics
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language:en
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Short-container-title:Atmos. Chem. Phys.
Author:
Chen SisiORCID, Xue LulinORCID, Tessendorf SarahORCID, Ikeda Kyoko, Weeks Courtney, Rasmussen Roy, Kunkel Melvin, Blestrud Derek, Parkinson Shaun, Meadows Melinda, Dawson NickORCID
Abstract
Abstract. In this study, a state-of-the-art microphysical model using a
Lagrangian-particle-based direct numerical simulation framework is presented
to examine the growth of ice particles in turbulent mixed-phase clouds. By
tracking the interactions between individual ice, droplets, and turbulence
at the native scales, the model offers new insights into the microphysical
processes taking place in mixed-phase clouds at sub-meter-length scales. This paper examines the conditions that favor effective ice growth in the
cloud-top generating cells (GCs), which are small regions of enhanced radar
reflectivity near cloud tops. GCs are commonly observed in many types of
mixed-phase clouds and play a critical role in producing precipitation from
rain or snow. Investigations over a range of environmental (macrophysical
and turbulent) and microphysical conditions (ice number concentrations) that
distinguish GCs from their surrounding cloudy air were conducted. Results show that high liquid water content (LWC) or high relative humidity
(RH) is critical for effective ice growth and the maintenance of mixed-phase
conditions. As a result, GCs with high LWC and high RH provide favorable
conditions for rapid ice growth. When the ice number concentration is below
1 cm−3, which is typical in mixed-phase clouds, a high LWC is needed
for the formation of large ice particles. The study also found that
supersaturation fluctuations induced by small-scale turbulent mixing have a
negligible effect on the mean particle radius, but they can substantially
broaden the size spectra, affecting the subsequent collection process.
Publisher
Copernicus GmbH
Subject
Atmospheric Science
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