Mixed-phase direct numerical simulation: ice growth in cloud-top generating cells
<p>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...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/5217/2023/acp-23-5217-2023.pdf |
| Summary: | <p>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.</p>
<p>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.</p>
<p>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<span class="inline-formula"><sup>−3</sup></span>, 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.</p> |
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| ISSN: | 1680-7316 1680-7324 |