基于热惯量的土壤湿度估算研究

Research on Estimating Soil Moisture by Using Thermal Inertia

冻土受冻土层上水和地表水等因素的影响,出现不均匀、不对称变形。因此,开展冻土区土壤水分的监测研究具有重要意义。本文提出了归一化相对湿度的概念,首先利用晴天风速较小的上午时刻的地表温差估算地表的简化热惯量,再利用日最高地表温度和最低地表温度得到归一化相对湿度。实验证明,本方法提供了一种估算土壤湿度的方法,但是为了得到更深层(大于40 cm)的土壤湿度,需要开展进一步的研究。

Frozen soils under subgrade affected by the water in the surface and upper the frozen soil,cause inhomogeneous and asymmetric surface deformation of subgrade.Therefore,it is significant to estimating surface soil moisture and deep soil water in permafrost regions.In order to estimate soil moisture,this paper proposed a method named normalization relative moisture,which was calculated by the simplified thermal inertia.Specifically,the simplified thermal inertia were estimated firstly by surface temperature differences from the time when net radiations were equal to zero to the time for MODIS transit.Secondly,the normalization relative moistures can be obtained by normalizing the biggest daily surface temperatures and smallest daily temperatures.The normalization relative soil moisture can be used to estimate soil moisture beyond 40 cm.Longer time interval will be used in estimating deep soil moisture in the future.