The Role of Ice Splintering on Microphysics of Deep Convective Clouds Forming under Different Aerosol Conditions: Simulations Using the Model with Spectral Bin Microphysics
Abstract
Observations during the Ice in Clouds Experiment-Tropical (ICE-T) field experiment of maritime deep convection show that the ice particles concentration in a developing deep convective clouds at the level of T = -15 °C reached about 500 L-1, i.e. several orders higher than that of ice nuclei (IN). To simulate microphysics of these clouds, the Hebrew University Cloud Model (HUCM) with spectral bin microphysics (SBM) scheme was used in which two main types of ice multiplication mechanisms were included. In the first ice multiplication mechanism ice splinters form by drop freezing and drop-ice collisions. Ice multiplication of this type dominates during developing stage of cloud evolution, when liquid water content (LWC) is significant. At later stage when clouds become nearly glaciated, ice crystals are produced largely by ice splintering during ice-ice collisions (the second ice multiplication mechanism). Simulations show that droplet size distributions (DSD), as well as size distributions of ice particles agree well with the measurements during ICE-T. Simulations were performed at different concentration conditions and size distributions of aerosol particles serving as cloud condensational nuclei (CCN) as well. Simulations with different CCN concentrations show the existence of the "optimum" CCN concentration (or droplet concentration), at which concentration of ice splinters reaches maximum. In these simulations primary ice nucleation caused by the direct transition of IN to ice crystals, as well as the secondary ice process based on Hallett-Mossop process have a negligible contribution to the ice crystal concentration.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A13O3064Q
- Keywords:
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- 3310 Clouds and cloud feedbacks;
- ATMOSPHERIC PROCESSES;
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES;
- 3314 Convective processes;
- ATMOSPHERIC PROCESSES