冻土-气候关系模型评述

冻土-气候关系模型是目前冻土学领域的研究热点,评述了冻土对气候系统的响应模型以及陆面过程模型中的各种冻土参数化方案.建立在传热学基础上的物理模型具有动态性、普适性的优点,适合于冻土工程计算,当把它们推广到面上时,需要对其进行简化.经验模型大都只使用有限的变量,与地理信息系统结合紧密,因此模型具有空间性,较为适合于冻土制图.陆面过程模型中的冻土参数化目前有3类方法:1)限定或修正水热参数;2)比较单位土层中耗热或放热量与可耗热或可放热量而计算产冰率;3)使用土壤基质势定义土壤冻结后的未冻水含量.现有的陆面过程模型中的冻土参数化方案需要进一步的改进.

Review on the Interaction Models between Climatic System and Frozen Soil

Modeling the interaction between frozen soil and climatic system is a major focus in the field of geocryology. It is also a concern of scientists to understand the responses of frozen soil to global warming. First, different kinds of frozen soil models developed in the last decade are reviewed in this paper. The physical models based on heat transfer are suitable for engineering calculation. However, when they are applied to environmental modeling, obstruction may occur for the difficult in initialization and parameterization, because they have very fine resolution and need many parameters. GIS aided models are usually empirically based; they need few parameters. Therefore, they are easy to be used for frozen soil mapping. Then, methods of frozen soil parameterization for land surface schemes were reviewed. There is insufficient attention paid to this parameterization until recent years. Most of the literatures appeared in the later 1990’s. These parameterization are different one another. To sum up, the parameterization can be assorted into three categories. The first category only accounts for the hydraulic and thermal properties of frozen soil. The second category calculates ice production rate based on the consumed/released heat and the potential consumed/released heat in a unit volume of soil. The third kind of frozen soil parameterization uses soil matric potential to define maximum liquid water content when soil temperature is below the freezing point. In the third category, liquid water content is a function of soil matrix potential and any additional water is ice.