~3He管中子土壤水分测量装置提高测量精度  

~3He tube neutron moisture measurement device improving measuring accuracy

作　　者：张杰[1] 刘刚[1] 李保国[1] 李贵桐[1] 

机构地区：[1]中国农业大学资源与环境学院,北京100193

出　　处：《农业工程学报》2018年第2期90-97,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(41371231)

摘　　要：宇宙射线中子法是一种先进的测定区域土壤水分含量的方法,但国内外对其制约因素的研究仍不成熟。该研究利用商业化宇宙射线中子仪(CRS1000)和自己组装的~3He管中子水分探测器(~3He管),在中国农业大学上庄试验站对土壤含水量进行持续监测,将测量的结果与烘干法测量的结果进行对比分析,验证2种仪器测量的准确性和稳定性,并比较2种仪器对土壤水分变化响应的灵敏性差异。研究结果显示,CRS1000和~3He管具有较高的稳定性,在太阳活动剧烈时,有必要考虑对中子入射强度进行校正;通过与烘干法获得的土壤水分数据比较,CRS1000和~3He管测量数据的均方根误差分别为0.036、0.015 cm^3/cm^3,说明2种仪器进行土壤水分测量的结果非常准确;利用2种仪器获得的土壤水分曲线的变化趋势具有较高的一致性,在降水事件发生时,2种仪器都迅速作出响应,但~3He管对土壤水分变化的反应更加灵敏,测量精度更高。同时,组装的~3He管中子水分探测器成本约为商业化宇宙射线中子仪的1/2,降低了成本,具有更加广阔的应用前景。As a significant part of water resources in the ecosystem cycle,soil moisture plays an extremely important role in the process of matter and energy exchange between the surface and the atmosphere.But it is very difficult to accurately measure large scale soil moisture.Cosmic-ray neutron method is a promising way to measure soil moisture for intermediate spatial scales.This method bridges the scale gap between point measurements of soil moisture and remote sensing,making significant contribution to the measurement of soil moisture within a regional level.In 2008,Zreda et al.introduced a method to measure average soil water content over a larger area with a cosmic-ray neutron sensor（CRS）.The footprint of a CRS covers a circle with an approximate radius of 300 m and the effective measurement depth varies between 10 and 70 cm below the soil surface.Desilets et al.proposed an equation with three constant shape parameters（a0,a1,a2） and one calibration parameter（N0）,which needs to be calibrated with soil moisture values determined by oven-drying method from field soil samples in 2010.Franz et al.（2013） developed a universal calibration function for determination of soil moisture with cosmic-ray neutrons that takes into account three influencing factors including pressure,incoming neutron flux and water vapor in the air.Meanwhile,other scholars have explored other factors that influence the soil moisture content,including the depth and range of detection,the lattice water,soil organic carbon and vegetation biomass.In this study,experiments were conducted in China Agricultural University Experiment Station with commercial cosmic-ray neutron sensors（CRS1000） and self-assembly ^3He tube neutron moisture detector（^3He tube）.In order to verify the accuracy and stability of these two instruments,we compared the soil moisture content data with the result from oven-drying method.Meanwhile,we made a comparison between the sensitivity of these two instruments for the response of precipitation event.Before u

关 键 词：土壤 水分 传感器 CRS1000 3He管 

分 类 号：TL817.1[核科学技术—核技术及应用]