Reconstructed annual glacier surface mass balance in the Ányêmaqên Mountains, Yellow River source, based on snow line altitude.

Annual mass balance is an important factor that reflects glacier change and glacier meltwater resources. In this study, we analyzed the changes in glacier area, snow line altitude (SLA) and surface elevation in the Ányêmaqên Mountain region using multisource remote sensing data. Then, the annual mass balance of two glaciers was reconstructed by using SLA-mass-balance gradient method. The results showed that the glacier area in the Ányêmaqên Mountains decreased by 29.4 km² from 1985 to 2017. The average SLAs of the Halong Glacier and Yehelong Glacier were approximately 5290 m and 5188 m, respectively. The glacier mass balance for the two glaciers from 1990 to 2020 was — 0.71 m w.e. a⁻¹ and −0.63 m w.e. a⁻¹, respectively. Our results indicate that SLA is an important indicator of glacier changes, and a long sequence of SLAs can more accurately reconstruct the glacier mass balance of the glacier. The mean annual glacial meltwater-fed streamflow is 1.45 × 10⁷ m³ and 1.12 × 10⁷ m³, respectively. Sensitivity analysis indicates that summer air temperature plays a leading role in regard to the influential climatic factors of glacial retreat in the Anyêmaqên Mountains. This highlights the potential of the methodology for application on reconstructing annual glacier surface mass balance at larger scales without direct measurements. [ABSTRACT FROM AUTHOR]