EGU25-18439, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-18439
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Modelling cloud phase and radiative effects in the European Arctic
Yaël Le Gars1, Jean-Christophe Raut2, and Louis Marelle3
Yaël Le Gars et al.
  • 1Sorbonne Université / CNRS, LATMOS, Paris - 75, Paris, France (yael.le-gars@latmos.ipsl.fr)
  • 2Sorbonne Université / CNRS, LATMOS, Paris - 75, Paris, France (jean-christophe.raut@latmos.ipsl.fr)
  • 3Sorbonne Université / CNRS, LATMOS, Paris - 75, Paris, France (louis.marelle@latmos.ipsl.fr)

Arctic clouds, which cover the region for around 70-80% of the year, are a key component of the Arctic climate system, influencing, among others, surface temperature, ice melt and atmospheric dynamics. Mixed-phase clouds, containing both supercooled liquid water and ice crystals, are of particular concern due to their prevalence in the Arctic and their role in the local energy budget. Because their variability and their lifecycle are inaccurately represented in models, they are an important source of uncertainty, as the cloud phase impacts both radiative effects, cloud lifetime and precipitation amounts. Assessing the vertical distribution of clouds, their optical properties and their phase distribution is therefore critical to accurately determine the surface energy balance (SEB). 

 

Here, the mesoscale WRF (Weather Research and Forecasting) updated for application in polar regions is run over the European Arctic from January to June 2015. The simulations are evaluated using observations from the N-ICE campaign, conducted from January through June 2015 in the drifting sea ice north of Svalbard (surface radiation and meteorology, atmospheric profiles), as well as satellite data derived from CALIPSO and CloudSat observations. The simulated SEB as well as low-level cloud distributions and phase partitioning are evaluated to get insight on the limitations of the model to represent Arctic clouds and the factors underlying these biases. 

 

This study reveals strong biases in radiative fluxes at the surface, even when cloudy conditions are successfully represented in the model, with effects varying across seasons. Results show that these discrepancies are likely to be strongly linked to the accurate phase characterization of clouds. Sensitivity tests based on variations in CCN and INP number concentrations reveal moderate effects on the radiative budget through changes in liquid water content, insufficient to account for the observed biases.

How to cite: Le Gars, Y., Raut, J.-C., and Marelle, L.: Modelling cloud phase and radiative effects in the European Arctic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18439, https://doi.org/10.5194/egusphere-egu25-18439, 2025.

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