Wu Zhen, Zhang Huiwen, Liu Shiyin, Ren Dong, Bai Xuejian, Xun Zhaojie, Ma Zhentao
Lanzhou Geophysical National Field Scientific Observation and Research Station, Earthquake Administration, Earthquake Administration of Gansu Province, Lanzhou, 730000, China.
State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou, 730070, China.
Sci Rep. 2019 Dec 27;9(1):20245. doi: 10.1038/s41598-019-56864-3.
Ice thickness has a great influence on glacial movement and ablation. Over the course of the change in thickness, area and external climate, the dynamic process of how glaciers change and whether a glacier's changes in melting tend to be stable or irregular is a problem that needs to be studied in depth. In our study, the changes in the dynamic process of the No. 8 Glacier in Hei Valley (H8) under the conditions of different thicknesses in 1969 and 2009 were simulated based on the Full-Stokes code Elmer/Ice (http://www.csc.fi/elmer/). The results were as follows: (1) The thickness reduction in glaciers would lead to a decrease in ice surface tension and basal pressure and friction at the bottom, and the resulting extensional and compressional flow played an important role in the variations in glacial velocity. (2) The force at the bottom of the glacier was key to maintaining the overall stress balance, and the glaciers that often melted and collapsed in bedrock were more easily destroyed by the overall force balance and increased change rate of glacial thaw. (3) Temperature changes at different altitudes affected the ice viscous force. The closer the ice surface temperature was to the melting point, the greater the influence of temperature changes on the ice viscous force and ice surface velocity. Finally, we used the RCP 4.8 and 8.5 climate models to simulate the changes in H8 over the next 40 years. The results showed that with some decreases in ice surface compression and tension, the gravity component changes caused by local topography begin to control the ice flow movement on the surface of glacier, and melting of the glacial surface will appear as an irregular change. The simulation results further confirmed that the fluctuation in glacial dynamic characteristics could be attributed to the change in the gravity component caused by ablation.
冰厚对冰川运动和消融有很大影响。在厚度、面积和外部气候的变化过程中，冰川如何变化以及冰川融化的变化趋于稳定还是不规则的动态过程是一个需要深入研究的问题。在我们的研究中，基于全斯托克斯代码Elmer/Ice（http://www.csc.fi/elmer/）模拟了1969年和2009年不同厚度条件下黑河谷8号冰川（H8）动态过程的变化。结果如下：（1）冰川厚度减小会导致冰面张力、底部压力和摩擦力减小，由此产生的拉伸和压缩流在冰川速度变化中起重要作用。（2）冰川底部的力是维持整体应力平衡的关键，在基岩中经常融化和坍塌的冰川更容易因整体力平衡和冰川融化变化率增加而被破坏。（3）不同海拔高度的温度变化影响冰粘性力。冰面温度越接近熔点，温度变化对冰粘性力和冰面速度的影响就越大。最后，我们使用RCP 4.8和8.5气候模型模拟了H8在未来40年的变化。结果表明，随着冰面压缩和张力有所减小，由局部地形引起的重力分量变化开始控制冰川表面的冰流运动，冰川表面融化将呈现不规则变化。模拟结果进一步证实，冰川动态特征的波动可归因于消融引起的重力分量变化。
