表碛下冰面消融模型的改进

An Improved Model for Estimating Ice Ablation under a Debris Cover

针对已有的表碛下冰面消融模型的缺点,通过对模型算法、模型假设和模型结构等方面进行改进,在模型的易用性和模拟精度上有了较大的提高.科其喀尔冰川的实例研究表明,改进模型对于表碛区不同试验点上地温的模拟是较好的,变化趋势基本一致,变化幅度也相当.但也存在模拟值与实测值之间变化相位差异的突出问题,实际操作可以通过适当的校正程序得以较好的解决.模型中对表碛热参数的常数化处理不会产生较大的模拟误差,此外计算开始时均一表碛温度的假设不会对表碛温度的整体模拟效果产生较大的影响.通过地温模拟得到的冰面消融速率与利用实测表碛热通量计算的冰面消融速率的比较说明,模型思路合理且算法可行.

In this paper, an improved model with upswing numerical solution, model assumption and model structure for estimating ice ablation under a debris cover is proposed to present a robust model and to reduce the errors as compared with the previous models. The case study on Koxkar Glacier shows that, in general, the agreement between the simulated and observed debris temperatures is good. The diurnal variability of the observed debris temperature is well captured by the proposed model. However, there is a phase difference between the simulated and observed debris temperatures. In practice, this problem can be handled by a phase correction procedure, which applies a properly selected phase lag in calibration period to the simulation period. The case study also shows that the two seemingly restrictive assumptions, constant debris thermal properties and uniform debris temperature profile at the beginning of the computation, have no adverse impact on the model simulation. Analyzing the relation between the simulated and observed ice ablation rates also shows that the model is good.