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Vaughan Phillips

Research in the Area of Clouds, Aerosols and Climate

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Impacts of secondary ice production on Arctic mixed-phase clouds based on ARM observations and CAM6 single-column model simulations

Author

  • Xi Zhao
  • Xiaohong Liu
  • Vaughan T.J. Phillips
  • Sachin Patade

Summary, in English

For decades, measured ice crystal number concentrations have been found to be orders of magnitude higher than measured ice-nucleating particle number concentrations in moderately cold clouds. This observed discrepancy reveals the existence of secondary ice production (SIP) in addition to the primary ice nucleation. However, the importance of SIP relative to primary ice nucleation remains highly unclear. Furthermore, most weather and climate models do not represent SIP processes well, leading to large biases in simulated cloud properties. This study demonstrates a first attempt to represent different SIP mechanisms (frozen raindrop shattering, ice ice collisional breakup, and rime splintering) in a global climate model (GCM). The model is run in the single column mode to facilitate comparisons with the Department of Energy (DOE) s Atmospheric Radiation Measurement (ARM) Mixed-Phase Arctic Cloud Experiment (MPACE) observations. We show the important role of SIP in four types of clouds during M-PACE (i.e., multilayer, single-layer stratus, transition, and frontal clouds), with the maximum enhancement in ice crystal number concentrations up to 4 orders of magnitude in moderately supercooled clouds. We reveal that SIP is the dominant source of ice crystals near the cloud base for the long-lived Arctic single-layer mixed-phase clouds. The model with SIP improves the occurrence and phase partitioning of the mixed-phase clouds, reverses the vertical distribution pattern of ice number concentrations, and provides a better agreement with observations. The findings of this study highlight the importance of considering SIP in GCMs.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • MERGE: ModElling the Regional and Global Earth system
  • eSSENCE: The e-Science Collaboration

Publishing year

2021

Language

English

Pages

5685-5703

Publication/Series

Atmospheric Chemistry and Physics

Volume

21

Issue

7

Document type

Journal article

Publisher

Copernicus GmbH

Topic

  • Meteorology and Atmospheric Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 1680-7316