Flying into the Cold: First Results from the NSF Cold-Air outbreak Experiment in the Sub-ARctic (CAESAR)

Paquita Zuidema; Bart Geerts; Greg McFarquhar; Adriana Bailey; John Cassano; James Doyle; Jeffrey French; Russell Perkins; Markus Petters; Jefferson R. Snider; Yonggang Wang; Zhien Wang; Lintong Cai; Robert David; Paul J. DeMott; Andrew Dzambo; Coltin Grasmick; Emma Järvinen; Pavel Romashkin; Elise Rosky; Carol Ruchti; Michael Tjernström; Peisang Tsai; Patrick Veres; Holger Vömel; Sarah Woods; Cory Wolff; Daniel Zietlow; John Allison; Nick Amundsen; Janine Aquino; Clayton Arendt; Aaron Bansemer; Eric Beamesderfer; Ezekiel Caldon; Teresa Campos; Tim Carlsen; Bo Chen; Owen Cruikshank; Catherine Dewerd; Gregory Elsaesser; Samuel Ephraim; Mack Goodstein; Sarah Gryskewicz; Julie Haggerty; Justin Hicks; Yongjie Huang; Timothy Juliano; Natalie Kille; Sonia Kreidenweis; Chris Kruse; Bee Lamsma; Scot Loehrer; Genevieve Lorenzo; Sunandan Mahant; Adam Majewski; Shane Martrich; Camille Mavis; Flynn McGinnity; Evy McUmber; Evan Newman; Qing Niu; Louis Nguyen; Gunnar Noer; Saurabh Patil; Ryan Patnaude; Erika Pruitt; Josephine Ragland; Michael Reeves; Amanda Richter; Anna Robertson; Franziska Rogge; Mampi Sarkar; Martin Schnaiter; Andrew Seidl; Harald Sodemann; Gunilla Svensson; William Smith; Susan Stringer; Tyler Tatro; Florian Tornow; Pablo Velt; Emma Weissburg; Jingbo Wu; Lulin Xue; Zeqian Xia

doi:10.1175/BAMS-D-25-0241.1

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Flying into the Cold: First Results from the NSF Cold-Air outbreak Experiment in the Sub-ARctic (CAESAR)

Journal article

Peer reviewed

Flying into the Cold: First Results from the NSF Cold-Air outbreak Experiment in the Sub-ARctic (CAESAR)

Paquita Zuidema, Bart Geerts, Greg McFarquhar, Adriana Bailey, John Cassano, James Doyle, Jeffrey French, Russell Perkins, Markus Petters, Jefferson R. Snider, …

Bulletin of the American Meteorological Society

2026-07-20

DOI: https://doi.org/10.1175/BAMS-D-25-0241.1

Appears in Rosenstiel School - Latest Publications

Abstract

The National Science Foundation-sponsored Cold-Air outbreak Experiment over the Sub-Arctic Region (CAESAR) is motivated by hypotheses in how dynamical, aerosol and cloud microphysical processes influence cold-air outbreak development and the accompanying spatial organization of clouds and precipitation, including in polar lows. CAESAR characterized the aerosol, thermodynamic and dynamic environment occupied by mixed-phase clouds within air masses moving southward off the Arctic sea ice over the Greenland/Norwegian Seas in the spring of 2024. The aircraft campaign supported a suite of remote sensing and in situ measurements below, within and above the mostly shallow convective clouds. Three flights reached the Greenland Marginal Ice Zone. A golden-case cold-air outbreak, sampled from its origin in clear skies over 100% sea ice, revealed a boundary layer containing anthropogenically-modified air, with the first-detected in situ cloud particles being ice polycrystals, within -25 °C air. Two flights sampled polar lows, and another flight characterized a closed-to-open cell transition occurring under high aerosol loading originating from Siberia and strong surface fluxes. The transition occurred after drizzle-sized drops developed within a boundary layer deepening under a weakening inversion. Combined ice particle and ice nucleating particle concentrations suggest most ice production is primary at cloud temperatures < -20 °C, with secondary ice production evident at cloud temperatures > -20 °C. Overall these first observations already reveal a diversity of CAO cloud structures.

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Title: Flying into the Cold: First Results from the NSF Cold-Air outbreak Experiment in the Sub-ARctic (CAESAR)
Creators: Paquita Zuidema - University of Miami
Bart Geerts - University of Wyoming
Greg McFarquhar - Cooperative Institute for Mesoscale Meteorological Studies
Adriana Bailey - University of Michigan
John Cassano - University of Colorado Boulder
James Doyle - United States Naval Research Laboratory
Jeffrey French - University of Wyoming
Russell Perkins - Colorado State University
Markus Petters - University of California, Riverside
Jefferson R. Snider - University of Wyoming
Yonggang Wang - State University of New York at Oswego
Zhien Wang - Stony Brook University
Lintong Cai - University of California, Riverside
Robert David - University of Oslo
Paul J. DeMott - Colorado State University
Andrew Dzambo - Cooperative Institute for Mesoscale Meteorological Studies
Coltin Grasmick - University of Wyoming
Emma Järvinen - University of Wuppertal
Pavel Romashkin - NSF National Center for Atmospheric Research
Elise Rosky - NSF National Center for Atmospheric Research
Carol Ruchti - NSF National Center for Atmospheric Research
Michael Tjernström - Stockholm University
Peisang Tsai - NSF National Center for Atmospheric Research
Patrick Veres - NSF National Center for Atmospheric Research
Holger Vömel - NSF National Center for Atmospheric Research
Sarah Woods - NSF National Center for Atmospheric Research
Cory Wolff - NSF National Center for Atmospheric Research
Daniel Zietlow - NSF National Center for Atmospheric Research
John Allison - NSF National Center for Atmospheric Research
Nick Amundsen - Cooperative Institute for Mesoscale Meteorological Studies
Janine Aquino - NSF National Center for Atmospheric Research
Clayton Arendt - NSF National Center for Atmospheric Research
Aaron Bansemer - NSF National Center for Atmospheric Research
Eric Beamesderfer - University of Wyoming
Ezekiel Caldon - State University of New York at Oswego
Teresa Campos - NSF National Center for Atmospheric Research
Tim Carlsen - University of Oslo
Bo Chen - Colorado State University
Owen Cruikshank - University of Wyoming
Catherine Dewerd - NSF National Center for Atmospheric Research
Gregory Elsaesser - Goddard Institute for Space Studies
Samuel Ephraim - University of Miami
Mack Goodstein - NSF National Center for Atmospheric Research
Sarah Gryskewicz - State University of New York at Oswego
Julie Haggerty - NSF National Center for Atmospheric Research
Justin Hicks - NSF National Center for Atmospheric Research
Yongjie Huang - Cooperative Institute for Mesoscale Meteorological Studies
Timothy Juliano - NSF National Center for Atmospheric Research
Natalie Kille - University of Wyoming
Sonia Kreidenweis - Colorado State University
Chris Kruse - NSF National Center for Atmospheric Research
Bee Lamsma - State University of New York at Oswego
Scot Loehrer - NSF National Center for Atmospheric Research
Genevieve Lorenzo - University of Miami
Sunandan Mahant - University of California, Riverside
Adam Majewski - University of Wyoming
Shane Martrich - University of Wyoming
Camille Mavis - Colorado State University
Flynn McGinnity - Stony Brook University
Evy McUmber - NSF National Center for Atmospheric Research
Evan Newman - University of Wyoming
Qing Niu - Cooperative Institute for Mesoscale Meteorological Studies
Louis Nguyen - Langley Research Center
Gunnar Noer - Metas (Norway)
Saurabh Patil - Cooperative Institute for Mesoscale Meteorological Studies
Ryan Patnaude - Colorado State University
Erika Pruitt - Cooperative Institute for Mesoscale Meteorological Studies
Josephine Ragland - Stony Brook University
Michael Reeves - NSF National Center for Atmospheric Research
Amanda Richter - Cooperative Institute for Mesoscale Meteorological Studies
Anna Robertson - University of Wyoming
Franziska Rogge - Karlsruhe Institute of Technology
Mampi Sarkar - Rice University
Martin Schnaiter - University of Wuppertal
Andrew Seidl - University of Bergen
Harald Sodemann - University of Bergen
Gunilla Svensson - Stockholm University
William Smith - Langley Research Center
Susan Stringer - NSF National Center for Atmospheric Research
Tyler Tatro - University of Miami
Florian Tornow - Goddard Institute for Space Studies
Pablo Velt - University of Wyoming
Emma Weissburg - University of Wyoming
Jingbo Wu - Goddard Institute for Space Studies
Lulin Xue - NSF National Center for Atmospheric Research
Zeqian Xia - Cooperative Institute for Mesoscale Meteorological Studies
Publication Details: Bulletin of the American Meteorological Society
Academic Unit: Rosenstiel School; Rosenstiel - Atmospheric Sciences
Language: English
Resource Type: Journal article
Record Identifier: 991033156660702976