基于SNTHERM雪热力模型的东北地区季节冻土温度模拟

Simulation of seasonally frozen soil temperature based on the Snow Thermal Model (SNTHERM) in Northeast China

冬季土壤温度在土壤肥力、植被安全越冬、土壤微生物活动中扮演着重要角色。雪盖的反照与隔热作用对冬季土壤温度变化及冻融过程具有一定影响,深入探究积雪覆盖对土壤温度的影响机制有十分重要的意义。雪热力模型(Snow Thermal Model,SNTHERM)是用来模拟和预测积雪演化和冻土温度的一维质能平衡模型。基于该模型,结合积雪下冻土温度的观测试验,通过模型模拟结果与实测数据的统计特征参数分析,进行了积雪覆盖下冻融土壤温度变化过程模拟的有效性和精度评价。结果表明,在积雪覆盖条件下,SNTHERM模型能够有效地模拟雪盖下浅层(5 cm、10 cm、15 cm深度)冻土日平均温度的变化过程,模拟值与观测值具有很好的一致性。通过改进模型中土壤层水分迁移等因素,能够提高冻土温度的模拟精度,为研究积雪各参数演化过程与下垫面温度的相互作用奠定理论基础,有助于提高积雪参量空间遥感的反演精度。

Soil temperature has a major impact on soil fertility,plantation overwintering and microbial activities.Snow cover has albedo and insulation effect which will affect soil temperature and its freeze-thawcycling in winter,and thus studying the impact of snowcover on soil temperature through effective model simulation is of great importance in the context of global change. The Snow Thermal Model（SNTHERM ） is a one-dimensional heat and mass transfer model,which is able to predict temperature profile within snowcover and frozen soil. In this paper,the model combined with the dynamic observation of frozen soil temperature,adopted the statistical parameters and Nash-Sutcliffe efficiency coefficient,is applied to assess the accuracy and efficiency of the simulation of temperature change process of freezing-thawing soil under snowcover. The results showed that SNTHERM is able to simulate effectively the changing process of daily mean soil temperature at the depths of 5,10,15 cm under the snowcover with good agreement. The study revealed that the model having a good applicability under snowcover,which has improved the inversion accuracy of snowparameters. It is also suggested that the simulated accuracy of the soil water content will affect the simulated accuracy of soil temperature without snowcover,which reveals that considering the liquid movement in the model could improve the simulating accuracy.