14 Mar 2022
14 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Snowfall in Northern Finland derives mostly from ice clouds

Claudia Mignani1, Lukas Zimmermann1, Rigel Kivi2, Alexis Berne3, and Franz Conen1 Claudia Mignani et al.
  • 1Department of Environmental Sciences, University of Basel, 4056 Basel, Switzerland
  • 2Space and Earth Observation Centre, Finnish Meteorological Institute, 99600 Sodankylä, Finland
  • 3Environmental Remote Sensing Laboratory, Swiss Federal Institute of Technology in Lausanne, 1015 Lausanne, Switzerland

Abstract. Cloud properties play a critical role in the Arctic surface energy budget. We present ground-level observations of snowfall coinciding with radiosonde launches in Sodankylä (67.367° N, 26.629° E) through a period of eight cold months (October–April) in 2019 and 2020. They comprise 7401 depositing snow particles detected by a snowflake camera and 468 radiosonde profiles. Our results show that precipitating clouds were extending from ground to at least 2.7 km in altitude. Approximately one quarter of them were mixed-phase and the rest were likely fully glaciated. Estimations of the cloud top temperatures indicate that in roughly half of the snowfall events ice might have been initiated through heterogeneous freezing. For such cases, the predicted ice-nucleating particle concentrations active at cloud top temperatures could explain the analysed ice crystal particle concentrations observed near ground. In a warmer climate, the relative proportion of solid to liquid cloud particles will probably decrease, with implications on the Arctic radiation balance.

Claudia Mignani et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-98', Anonymous Referee #3, 05 Apr 2022
  • RC2: 'Comment on acp-2022-98', Anonymous Referee #2, 05 Apr 2022

Claudia Mignani et al.

Claudia Mignani et al.


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Short summary
In the Arctic clouds play a critical role in surface warming, depending on their phase. We determined over the course of eight winter months the phase of clouds in Northern Finland using radiosondes and observations of snow particle habits at ground level. We found that precipitating clouds were extending from near ground to at least 2.7 km altitude and approximately three quarters of them were ice-phase. Likely moisture sources and possible ice formation processes are discussed.