In-situ optical characterization of ice fog and diamond dust events at DOME-C, Antarctica

In-situ measurements of small atmospheric ice crystals (< 100 µm) on the Antarctic plateau are rare. Yet, small ice crystals are abundant in a region that often reaches cirrus temperatures even in the warmest season. The Particle Phase Discriminator (PPD-2K) was deployed on DOME-C, Antarctica during austral summer 2023/2024. It was used to characterize the microphysical and optical properties of individual ice fog and diamond dust ice crystals having sizes between approximately 10 and 100 µm. These properties included particle concentration, size distribution and spatial light scattering patterns in the forward direction that allow the analysis of the particle sphericity (particle phase), shape and crystal complexity.
The atmospheric ice crystals on the Antarctic plateau commonly appear in form of ice fogs that have an effect on the radiative budget. In this presentation an ice fog event occurring between 26.11.2023 and 27.11.2023 is analyzed in detail using additional data from LIDAR, temperature and humidity sensors operated at DOME-C. The results are compared to previous findings in Antarctica and to ice fog measurements with the same instrument in a polluted environment at Fairbanks, Alaska.