Assessing the dynamic changes and the effect of buoyancy of lake-terminating Yanong Glacier in the southeastern Tibetan Plateau with UAV surveys

Study region: Yanong Glacier, a lake-terminating glacier, in the southeastern Tibetan Plateau. Study focus: Previous researches had indicated higher mass loss of lake-terminating glaciers than land-terminating glaciers over the past few decades. However, the annual variability of lake-terminating glaciers, and the interaction between glaciers and lakes is still unclear. Here, we conducted two Uncrewed Aerial Vehicle (UAV) surveys to estimate the height changes and surface velocity of the tongue of lake-terminating Yanong Glacier, and try to find out the effect of proglcial lake on glacier dynamic changes. New hydrological insights for the region: Results showed that the vertical uplift from buoyancy in glacier tongue causes an underestimation of mass loss of about 8 % over the entire Yanong Glacier, compared to the simulated mass balance. In addition to the vertical uplift, the buoyancy decreases the effective pressure of glacier terminus and causes more ice calving. Furthermore, the proglacial lake increases the subglacial hydrostatic pressure, resulting in a strong increase in glacier surface velocity. We estimate that the effect of the proglacial lake on glacier dynamic changes will last for more than 70 years, assuming that the proglacial lake expands at a rate of 0.1 km² a⁻¹ in the future. Overall, our study shows the importance to consider the effect of pro-glacial lakes and glacier dynamic changes in modelling and projecting glacier dynamics.