Introduction

In our study, we explored the variability and properties of liquid-dominated clouds over the ice-free and sea-ice-covered Arctic Ocean. Given the critical role of these clouds in influencing the Arctic energy budget and surface temperature, understanding their characteristics is essential for climate modeling, particularly in the context of Arctic amplification. Our analysis utilized data from the ACLOUD (Arctic CLoud Observations Using airborne measurements during polar Day) campaign in summer 2017 and the AFLUX (Arctic Amplification: FLUXes in the Cloudy Atmospheric Boundary Layer) campaign in spring 2019.

Cloud Properties Over Sea Ice and Open Ocean

We retrieved the microphysical properties of liquid-phase clouds using airborne measurements of solar spectral cloud reflectivity. Our findings indicated that in early summer, liquid-phase clouds over the ice-free Arctic Ocean exhibited larger median effective radii, optical thicknesses, and liquid water paths compared to spring conditions. Specifically, we observed larger cloud droplets over the ice-free ocean than over sea ice, driven mainly by temperature differences and associated convection processes.

Methodology and Data Analysis

Our retrieval method, based on the bispectral approach, was tailored to distinguish liquid-dominated clouds and was validated against in situ measurements. However, we found that the retrieved liquid water path (LWPeff) was often overestimated, particularly in the presence of ice particles within the clouds. Despite these challenges, our results are consistent with in situ observations, demonstrating the validity of the retrieval method for Arctic mixed-phase clouds with dominant liquid layers at the cloud top.

Conclusion

Our research contributes to a deeper understanding of the microphysical properties of Arctic liquid-phase clouds and their impact on the radiation budget. The observed differences between cloud properties over sea ice and the open ocean are crucial for refining climate models, especially in the rapidly changing Arctic environment. The comprehensive dataset generated from this study is publicly available and can serve as a valuable resource for further investigations.

This summary is based on our publication: Klingebiel, M., Ehrlich, A., Ruiz-Donoso, E., Risse, N., Schirmacher, I., Jäkel, E., Schäfer, M., Wolf, K., Mech, M., Moser, M., Voigt, C., and Wendisch, M. (2023). Variability and properties of liquid-dominated clouds over the ice-free and sea-ice-covered Arctic Ocean. Atmos. Chem. Phys., 23, 15289–15304. doi.org/10.5194/acp-23-15289-2023.