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土壤的冻结和融化是土壤内部的重要物理过程,其冻融界面位置的移动影响土壤水热特性以及陆面和大气之间的水分能量交换,从而对陆面水热过程产生重要影响.本研究将土壤冻结和融化问题归结为考虑水热耦合的多运动边界问题,利用局部自适应变网格法进行数值离散,发展了考虑冻结和融化界面位置的移动对水热过程影响的土壤水热耦合模型.该模型基于陆面模式分层结构的敏感性试验表明:它能同时连续地追踪多个冻融界面,克服了等温线法在同一土壤层不能同时模拟多个冻融界面的困难,比高分辨率情形下的计算效率提高数倍且计算稳定.利用站点观测对土壤冻融界面的位置、土壤温度和未冻水含量所进行的模拟验证,进一步表明了该模型的合理性以及应用于陆面过程模式的模拟潜力.
The freezing and thawing of soil is an important physical process inside the soil, and the movement of freeze-thaw interface affects the hydrothermal characteristics of the soil and the exchange of moisture energy between the land surface and the atmosphere, which has an important impact on the hydrothermal processes on the land surface. The problem of soil freezing and thawing is attributed to the multi-motion boundary problem considering hydrothermal coupling. The local adaptive mesh method is used to carry out the numerical discretization, and the soil hydrothermal coupling which affects the hydrothermal process due to the movement of frozen and thawed interface has been developed Model.The sensitivity of the model based on land surface model stratification shows that it can track a number of freeze-thaw interfaces simultaneously and overcome the difficulty that the isotherm method can not simultaneously simulate multiple freeze-thaw interfaces in the same soil layer The computational efficiency is improved several times in high resolution and the calculation is stable.Using site observation to simulate the location of soil freezing and thawing interface, soil temperature and unfrozen water content further proves the rationality of this model and its application to Land surface process model of the simulation potential.