高压线电磁场强度对大孔径闪烁仪观测的影响

Effect of high voltage wire electromagnetic field intensity on Large Aperture Scintillometer(LAS) observation

大孔径闪烁仪(Large Aperture Scintillometer,LAS)是测量水平距离上250～4 500 m地表能量平衡和水热通量的仪器。在其红外波传输的过程中会受到环境因素以及下垫面属性的影响。鉴于外界条件的复杂性,还会受到树木的阻挡以及高压线电磁场辐射等因素的影响。本文通过分析2009年8月～2010年3月在中国科学院栾城农业生态系统试验站开展LAS观测过程中的影响因素,研究了高压输电线电磁场对LAS观测的影响。结果表明,当LAS红外光路径距高压线过近时对测定的感热通量HLAS影响较大,导致计算结果与实际不符。通过计算提出了避免高压输电线电磁场干扰LAS观测信号的安全安装距离应是保证高压输电线电磁场强度小于4.05μT的距离。结果可为开展同类观测试验提供参考。

Large Aperture Scintillometer was widely used to measure horizontal distance（250～4 500 m） surface energy balance and fluxes of water and heat.In transmitting infrared waves,several environmental factors and land surface properties affect LAS signal.Further given the complexity of external conditions,high trees and electromagnetic fields of high voltage wires in the path of LAS light also blur receiver signal detection.Through experimentation at Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences in August 2009 through March 2010,this paper,analyzed the effects of electromagnetic fields of high voltage wires on LAS observation.The result indicated when the space between the path of LAS infrared waves and high voltage wire was too narrow,measured sensitive heat flux（HLAS） was greatly affected,causing the difference between the calculations and the practice.Following detailed analysis of the experimental data,the paper suggested safe distance,in which electromagnetic field intensity should be less than 4.05 μT,from high voltage wires during LAS installation in densely populated areas.The study would extremely benefit and improve future LAS observations.