Energy and mass balance characteristics of the Guliya ice cap in the West Kunlun Mountains, Tibetan Plateau

Glacier surface ablation and associated energy characteristics are important to glacier survival, but little is known about these on glaciers in the West Kunlun Mountains (WKM), Tibetan Plateau, mainly due to their inaccessibility. Based on the glacio-meteorological conditions and mass balance observations on the Guliya ice cap (GIC) in the WKM during 2015/'16, a distributed energy and mass balance model was applied to study the spatiotemporal variations of energy and mass balance on the GIC, and the response of mass balance to climate change. Modeled results revealed that compared to the Chongce glacier in the WKM which was observed to undergo a positive mass balance in the 1980s, the GIC suffered a small mass loss with an annual value of - 0.193 +/- 0.042 m water equivalent, and the equilibrium-line altitude has risen by approximately 70 m to locate at 6000 +/- 19 m. Besides, over the entire observation period, the incoming energy supplied by net shortwave radiation was almost balanced by the energy loss through net longwave radiation, and most energy available for surface ablation was consumed by latent heat flux through sublimation, which became a significant feature of the energy balance on the GIC. Sensitivity experiments by changing model input data with synthetic climate scenarios, which were sampled from meteorological measurements and accounted for coupled climate variable perturbations, revealed that the mass balance of the GIC was more sensitive to the changes in moisture-related variables than that in temperature, and positive mass balance would only be given from scenarios with significantly increased annual precipitation and decreased air temperature compared to those observed in 2015/'16.