The distinctive characteristics of glacier surface melt under the combined control of westerlies and monsoon in the northeastern Tibetan Plateau

Author links open overlay panelShu-Hai GUO ^a, Yue-Ping LI ^b, Ren-Sheng CHEN ^{a c}, Chun-Tan HAN ^a

As a key part of the Asian Water Tower, the glaciers in the northeastern Tibetan Plateau (TP) experience the mass balance changes jointly regulated by the westerlies and monsoon circulation. However, the mechanisms driving glacier melt in this region under complex atmospheric circulation remain unclear. This study investigates wind-driven energy allocation and its impact on glacier melt using four years (2018–2021) of meteorological and surface energy balance (SEB) data from an automatic weather station (AWS) on the August-one glacier, a flat-topped glacier in the westerlies–monsoon transition zone of the TP. Results reveal that westerly winds suppress melt primarily through cold air advection, markedly lowering near-surface temperatures and intensifying net longwave radiation loss (L_net). Despite increasing shortwave radiation under reduced cloudiness, the combined effects of low temperatures and enhanced L_net depletion limit net energy accumulation (R_net), resulting in a ‘low temperature–high albedo–low energy’ feedback loop. Conversely, easterly (local valley winds) and southerly winds (monsoon-influenced) dominate melt during the melt-season (71% of cumulative melt) by transporting warm–humid airflows that elevate cloud cover and inhibit longwave heat loss, thereby increasing melt efficiency. Radiation conversion efficiency (η) declines by 70% as westerly wind speeds increase (1–11 m/s), highlighting dynamic energy reallocation caused by cold advection. These findings challenge the traditional emphasis on shortwave radiation dominance, underscoring the coupled roles of wind regimes, temperature and longwave radiation in melt dynamics.