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Mixed-phase clouds and precipitation in Southern Ocean cyclones and cloud systems observed poleward of 64 degrees S by ship-based cloud radar and lidar

Citation

Alexander, SP and McFarquhar, GM and Marchand, R and Protat, A and Vignon, E and Mace, GG and Klekociuk, AR, Mixed-phase clouds and precipitation in Southern Ocean cyclones and cloud systems observed poleward of 64 degrees S by ship-based cloud radar and lidar, Journal of Geophysical Research: Atmospheres, 126, (8) Article e2020JD033626. ISSN 2169-897X (2021) [Refereed Article]


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DOI: doi:10.1029/2020JD033626

Abstract

Mixed-phase clouds (MPCs), composed of both liquid and ice, are prevalent in Southern Ocean cyclones. A characterization of these clouds on fine vertical scales is required in order to understand the microphysical processes within these clouds, and for model and satellite evaluations over this region. We investigated three examples of cloud systems collected by ship-mounted remote-sensing instruments adjacent to East Antarctica at latitudes between 64S and 69S. These cases allow us to examine the properties of midlevel MPCs, with cloud tops between 2 and 6 km. Midlevel MPCs contain multiple layers of supercooled liquid water (SLW) embedded within ice during the passage of cyclones. SLW layers are capped by strong temperature inversions and are observed at temperatures as low as −31C. Convective generating cells (GCs) are present inside supercooled liquid-topped midlevel MPCs. The horizontal extent, vertical extent, and maximum upward Doppler velocity of these GCs were 0.63.6 km, 0.71.0 km, and 0.51.0 m s−1, respectively, and are consistent with observations from previous lower-latitude studies. Ice precipitation is nearly ubiquitous, except in the thinnest clouds at the trailing end of the observed systems. Seeding of lower SLW layers from above leads to periods with either larger ice particles or greater ice precipitation rates. Periods of supercooled drizzle lasting up to 2 h were observed toward the end of two of the three cyclone systems. This supercooled drizzle turns into predominantly ice precipitation as the result of seeding by ice clouds located above the precipitating SLW layer.

Item Details

Item Type:Refereed Article
Keywords:lidar, mixed-phase clouds, precipitation, radar, Southern Ocean
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Antarctic and Southern Ocean oceanic processes
UTAS Author:Alexander, SP (Dr Simon Alexander)
UTAS Author:Protat, A (Dr Alain Protat)
UTAS Author:Klekociuk, AR (Dr Andrew Klekociuk)
ID Code:150343
Year Published:2021
Web of Science® Times Cited:4
Deposited By:Australian Antarctic Program Partnership
Deposited On:2022-06-09
Last Modified:2022-06-09
Downloads:0

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