ALBERT

Description: Villarrica Volcano is an active ice-covered volcano in southern Chile (2847 m a.s.l., 39°25’12’’ S, 71°56’27’’W), with a current glacier extent of 23.6 km〈sup〉2〈/sup〉. To investigate meteorological conditions and the impact of ongoing climatic warming on glacier melt, an automatic weather station (AWS) was installed at 1900 m a.s.l. on a tephra-covered surface in the glacier ablation zone in December 2019, providing continuous measurements of meteorological variables and tephra temperatures. To give further insight into the turbulent fluxes of sensible and latent heat at the glacier surface, an eddy covariance system, consisting of a parallel-mounted 3D sonic anemometer and krypton hygrometer, was deployed over tephra and snow surfaces close to the AWS between 12-16 January 2023. During the summer, snow and ice are subject to intense insolation and positive air temperatures, with high melt rates further amplified by surface darkening from windblown low-albedo tephra. In contrast, ice beneath extensive areas of tephra cover in the lower ablation zone is effectively insulated, with much lower ablation rates. Both tephra and snow exhibit predominantly negative latent heat fluxes, indicating surface water evaporation, with notably high magnitude and variable fluxes at the tephra site during the afternoon when surface temperature exceeds 35°C. The snow site is predominantly a sink of atmospheric sensible heat, due to positive air temperatures, while the tephra site alternates between positive and negative sensible heat fluxes, determined by high daytime and low night-time surface temperature, respectively. These measurements will be used to inform approaches to modelling the turbulent fluxes.