Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： Debris-covered glaciers are widely distributed in Western China. Their ablation areas are covered byvarying degrees of rock debris, and consequently, their melting statuses differ greatly when compared to debrisfreeglaciers. There is currently a need for melting simulations to better understand debris- covered glaciers. Inthis paper, driven by field meteorological data, an energy balance model for debris- covered glaciers has beenused to simulate the energy and ablation in debris-covered areas of Qingbingtan Glacier No. 72 in Mt. Tomor,Tianshan. Based on the heat conduction process and the energy balance equation, the model calculates the debrissurface temperature and the internal temperature of the debris, then estimates the subdebris melt using the internaldebris temperature. The results showed that the modeled ablation was 0.39 m w.e. in the summer of 2008, and thesimulation accuracy (R2 = 0.92, RMSE = ± 0.03 m w.e.) was higher when compared with the field data. Thesimulated debris temperatures at the surface and a depth of 10 cm inside the debris were also found to fit wellwith the measured data (R2 = 0.91 and 0.60, respectively). During energy exchange in the debris area, netshortwave radiation was the only energy income item, and sensible heat flux was the largest energy expenditureitem (49.7%), followed by the heat conduction flux (ablation heat consumption) (25.8%), net longwave radiation(19.8%), and latent heat flux (4.6%), while precipitation heat was <1%. Cloud cover had a significant impact onthe meteorological and energy characteristics of the debris area. Under overcast conditions, the incomingshortwave radiation in the debris area decreased from 854 W·m- 2 on sunny days to 587 W·m− 2, while thedownward longwave radiation and relative humidity increased, and the average ablation decreased by 12%, whencompared with sunny days. In addition, the sensitivity analysis of the key parameters for debris shows that thesimulated ablation is most sensitive to the changes in thermal conductivity, and the changes in albedo and surfaceroughness cannot be ignored.
Subjects: Geosciences >> Geography submitted time 2020-12-17 Cooperative journals: 《干旱区研究》
Abstract：冰川物质平衡作为表征气候变化的重要指标，通常被用来评估冰川对径流及海平面上升的贡献。本文采用世界冰川监测服务处（World Glacier Monitoring Service, WGMS）最新公布的物质平衡、平衡线高度及积累区面积比率资料，以北极地区具有长时间观测序列的23条冰川为研究对象，分析了北极山地冰川物质平衡状况及物质平衡与平衡线高度和积累区比率的关系。分析表明：（1）1960—2017年北极冰川厚度平均减薄14.8 m，俄罗斯北极减薄最小，为4.3 m，阿拉斯加地区减薄最严重，为27.7 m；（2）23条冰川中，仅Engabreen冰川平均物质平衡为正值，Kongsvegen冰川保持微弱的负平衡，其他21条冰川的物质平衡均处于较强的负平衡状态，北极冰川整体物质损失严重；（3）过去60 a，北极冰川物质平衡整体呈负平衡，20世纪90年代后期开始，冰川开始加速消融，损失速率从-128.2 mm·a-1上升至-594 mm·a-1；（4）物质平衡与平衡线高度呈负相关，与积累区比率呈正相关，相关性显著；（5）北极气温升高是冰川物质消融的主要原因，90年代之后气温大幅度升高造成同期冰川物质大量流失，降水量对物质平衡影响较小
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