Surface energy balance of the Sygyktinsky Glacier, south Eastern Siberia, during the ablation period and its sensitivity to meteorological fluctuations

The physically based melt of the low elevation Eastern Siberian glaciers is poorly understood due to the lack of direct micrometeorological studies. We used an automatic meteorological station to record the meteorological and energy characteristics of the Sygyktinsky Glacier, south Eastern Siberia (56.8° N, 117.4° E, 2,560 m a.s.l.), during two ablation seasons and computed the surface energy balance (SEB) for 30-min intervals. The glacier ablation was both modeled and measured by stakes and a thermistor cable. The net radiation (R_net) was the main contributor (71-75 W m^-2, 89-95%) to the SEB (79 W m^-2, 100%), followed by sensible (2-4 W m^-2, 3-5%) and latent (2-3 W m^-2, 2-4%) heat fluxes. The net shortwave radiation was the main positive component of R_net, while the net longwave radiation was weak and either negative (- 15 W m^-2 in 2019) or positive (4 W m^-2 in 2020). The small proportion of turbulent fluxes in the SEB is explained by the low wind speed (1.2 m s^-1). The glacier ablation was found to be more sensitive to changes in shortwave radiation and wind speed, suggesting the need to consider the atmospheric conditions of the ablation period (summer snowfalls, cloudiness, wind speed) when analyzing long-term trends in glacial changes.