24 Aug 2022
24 Aug 2022
Status: this preprint is currently under review for the journal ACP.

Surface-based observations of cold-air outbreak clouds during the COMBLE field campaign

Zackary Mages1, Pavlos Kollias1,2, Zeen Zhu2, and Edward P. Luke2 Zackary Mages et al.
  • 1School of Marine and Atmospheric Sciences, Stony Brook, NY, USA
  • 2Environmental and Climate Sciences Dept., Brookhaven National Laboratory, Upton, NY, USA

Abstract. Cold-air outbreaks (CAOs) are characterized by extreme air-sea energy exchanges and low-level convective clouds over large areas in the high latitude oceans. As such, CAOs are an important component of the Earth’s climate system. The CAOs in the Marine Boundary Layer Experiment (COMBLE) deployment of the US Department of Energy Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) provided the first comprehensive view of CAOs using a suite of ground-based observations at the northern coast of Norway. Here, cloud and precipitation observations from 13 CAO cases during COMBLE are analysed. A vertical air motion retrieval technique is applied to the Ka-band ARM Zenith-pointing Radar (KAZR) observations. The CAO cumulus clouds are characterized by strong updrafts with magnitudes between 2–8 m s-1, vertical extents of 1–3 km, and horizontal scales of 0.25–3 km. A strong relationship between our vertical air velocity retrievals and liquid water path (LWP) measurements is found. The LWP measurements exceed 1 kg m-2 in strong updraft areas, and the vertical extent of the updraft correlates well with the LWP values. The CAO cumulus clouds exhibit large values of eddy dissipation rate. Finally, evidence of secondary ice production in the CAO cumulus clouds is presented.

Zackary Mages et al.

Status: open (until 05 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Zackary Mages et al.

Zackary Mages et al.


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Short summary
Cold-air outbreaks (when cold air is advected over warm water and creates low-level convection) are a dominant cloud regime in the Arctic, and we capitalized on ground-based observations, which did not previously exist, from the COMBLE field campaign to study them. We characterized the extent and strength of the convection and turbulence and found evidence of secondary ice production. This information is useful for model intercomparison studies that will represent cold-air outbreak processes.