涡动相关通量计算及三种主要软件的比较分析

Flux Calculation of Eddy-Covariance Method and Comparison of Three Main Softwares

涡动相关方法是当前地气交换研究中最基本的通量观测方法。依据有关观测数据计算所得的通量结果与湍流资料处理软件的配置关系很大。本文选择了国际上通用的三种主要涡动相关数据处理软件(即EdiRe、TK2/TK3和EddyPro),对国内外5个不同下垫面的通量站资料进行了比较分析。依据EdiRe计算模块逐步完善的EdiRe-w程序的处理结果与其他两个软件的比较表现出较好的一致性:(1)三个软件处理结果的相关性很高,各决定系数R2多数大于0.99;(2)所得风速、温度、水汽浓度和CO2浓度的平均值几乎完全一致;(3)动量通量(或摩擦速度u*)的比较,差别小于3%;感热、潜热和CO2通量的比较,EdiRe-w和EddyPro结果的差别一般小于5%;EdiRe-w和TK3的结果差异略大些,但即便对较难测量的潜热通量和CO2通量,相互差异也在9%以内。三个软件的比较结果表明,EdiRe软件具有模块功能较完备、搭配较灵活和运算速度明显较快的特点,是当前值得应用的好方法。

For flux observation at present research of land-atmosphere exchange system,eddy-covariance method(EC) is the most fundamental method.The calculated fluxes based on observation data are significantly influenced by the settings of turbulence data processing softwares.This paper comparatively analyzed the performance of three softwares(EdiRe,TK2/TK3 and EddyPro) based on EC data for different underlying surface collected from five domestic and foreign flux observation stations.Results calculated by EdiRe-w,which had been improved based on EdiRe modules from 2006,showed a good agreement with those calculated by the other two softwares.The specific conclusions are listed in the following:(1) Results of the three softwares showed a high correlation,and most of determination coefficients(R2) were higher than 0.99;(2) The mean values respectively calculated by three softwares were almost consistent with each other for wind speed,air temperature,vapor concentration and carbon dioxide concentration;(3) For the momentum flux(or friction velocity u*),the calculation differences were less than 3% for three softwares;and less than 5% for sensible heat flux,latent heat flux and carbon dioxide flux calculated by Edire-w and EddyPro;the differences between Edire-w and TK3 were a little larger,however,even for the latent heat flux and CO2 flux which are the most difficult to measure,they were still less than 9%.Finally,the comparatively analysis results suggested that EdiRe is an optimal software for processing EC data which is,with the characteristic of perfect function,flexibility in calling modules and fast computational speed.