Quantification of dust-induced bare ice albedo reduction on Parlung No. 4 Glacier, southeast Tibetan Plateau

Amid ongoing climate warming, accelerated seasonal snow loss has expanded the areal extent of bare ice on glaciers and prolonged its exposure during the ablation season. However, the impact of dust on bare ice albedo has received relatively little attention. Previous studies have largely focused on snow-covered glacier surfaces, despite the fundamental differences in physical structure and radiative-transfer mechanisms between snow and bare ice. To quantify the dust-induced reduction in bare ice albedo, we conducted in situ albedo measurements and collected bare ice samples on Parlung No. 4 Glacier (96.93°E, 29.26°N) in the southeastern Tibetan Plateau from May to June 2021. We applied the Snow, Ice, and Aerosol Radiation model, version SNICAR-ADv4, which is specifically designed for simulating ice albedo. Comparison with in situ measurements yielded a minimum MAE of 0.060. Under the reference configuration, dust reduced bare ice albedo by 0.21, compared with 0.056 for snow. Sensitivity tests showed that the estimated dust effect depends on dust optical properties, ice bubble radius, and ice density. Despite these sensitivities, the substantially greater albedo reduction for bare ice indicates that the transition from snow-covered to exposed bare ice conditions can enhance the radiative effect of dust during the ablation season.