Cryosphere-Atmosphere Interactions on the Edge: The Ice Cliff Boundary Layer

Land-terminating ice cliffs are rare features of the cryosphere, displaying unique atmosphere-cryosphere interactions due to their vertical nature. Although the ice cliff surface is small compared to the total glacier surface, the mass balance of the vertical face can play a decisive role in glacier ablation, due to the cliff's altered exposure to radiative fluxes and modulation of turbulent heat fluxes. Understanding the boundary layer fluxes over these vertical ice walls is therefore essential for accurately modeling the melt of the cliff and other related processes. Our research addresses this gap by analyzing turbulence and microclimate data collected from ice cliffs in two distinct climatic regions: northern Greenland and Kilimanjaro.

The dataset from Greenland includes low-frequency temperature and humidity observations from the vertical ice face and its surroundings, allowing us to characterize the microclimate of ice cliffs in polar environments. The Kilimanjaro site was additionally equipped with high-frequency instrumentation. These measurements provide reliable insights into the boundary layer structure and turbulent fluxes of heat and moisture. Therefore, using data from this site, we aim to evaluate whether heat and moisture fluxes calculated from low- and high-frequency measurements are consistent. This allows us to determine whether the low-frequency data is sufficient to calculate turbulent fluxes at sites without high-frequency instrumentation. The insights gained from these analyses can help improve the representation of turbulent fluxes in ice cliff melt models.

In summary, this work contributes to the broader understanding of cryosphere-atmosphere interactions at vertical ice cliffs, offering valuable insights into the boundary layer processes that control their melt under varying climatic conditions.