EGU25-18946, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-18946
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
How does the change from sea ice to open ocean alter Arctic mixed-phase clouds?
Nina Elisabeth Larsgård1, Rob O. David1, Tim Carlsen1, Alfons Schwarzenboeck3, Harald Sodemann2, and Trude Storelvmo1
Nina Elisabeth Larsgård et al.
  • 1Department of Geosciences, University of Oslo, Oslo, Norway (n.e.larsgard@geo.uio.no)
  • 2Geophysical Institute, University of Bergen, Bergen, Norway
  • 3Ecole Universitaire de Physique et Ingénierie, Ecole Observatoire de Physique du Globe de Clermont, Université Clermont Auvergne, France

Mixed-phase clouds consist of both liquid water and ice crystals, which affect their radiative properties. The amount of ice in the clouds is also important for the formation of precipitation and the lifetime of the clouds. Mixed-phase clouds are abundant in the Arctic, which through Arctic amplification is experiencing the largest and fastest changes in climate. Clouds, including Mixed-phase clouds, remain one of the biggest causes of uncertainty in climate models. The clouds' radiative effects depend on the composition, location, amount, and longevity of the clouds, which are complex properties both to measure and to model.

So how will the Arctic mixed-phase clouds change in a warming world? We expect warmer temperatures to lead to more liquid clouds, with smaller and more abundant cloud particles and thereby more reflective clouds. Ultimately resulting in surface cooling (temperature effect). However, increased warming also leads to a decrease in sea ice. Less sea ice will lead to changes in the available aerosols, making more locally emitted aerosols available to act as ice-nucleating particles (INPs), possibly resulting in ice forming at higher temperatures. Less sea ice can then lead to more ice in the clouds, resulting in less reflective clouds and surface warming (aerosol effect). 

The focus of this study is to investigate the changes in microphysical properties of the mixed-phase clouds over different surface conditions: How do the microphysical properties change as the sea ice disappears?

Aircraft measurements from the spring 2022 field campaign of the Isotopic Links to Atmospheric water's Sources (ISLAS) project are used to investigate the microphysical properties of Arctic mixed-phase clouds during Cold Air Outbreaks. These Cold air outbreaks act like a natural laboratory, which makes them ideal for studying the effect of the clouds from the same airmass over different surfaces such as sea ice and open ocean. 

The ISLAS flights from April 3rd, 2022 passed over both sea ice and open ocean and are used as a case study. We focus on cloud microphysical properties such as cloud droplet number concentration, size distribution, and the supercooled liquid fraction (SLF: liquid water content/ total water content), measured by in-situ cloud probes. We compare the results for the clouds encountered over sea ice vs. over open ocean, and at different heights within the clouds. Whether or not we see any differences for the clouds above sea ice vs. open ocean indicates which of the two processes, the temperature effect or the aerosol effect, dominates as the sea ice disappears in a warming climate.

How to cite: Larsgård, N. E., David, R. O., Carlsen, T., Schwarzenboeck, A., Sodemann, H., and Storelvmo, T.: How does the change from sea ice to open ocean alter Arctic mixed-phase clouds?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18946, https://doi.org/10.5194/egusphere-egu25-18946, 2025.