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利用帽儿山温带落叶阔叶林通量塔8层CO2/H2O浓度廓线的测定数据,比较分析了基于不同浓度变量[密度(ρc)、摩尔分数(cc)和混合比(χc)]计算CO2储存通量(Fs)的误差.结果表明:通量观测的控制体积内部干空气储存量不为常数,其波动可引起CO2分子进出控制体积,即干空气储存通量调整项(Fsd)的变化.在夜间以及昼夜转换期,Fsd相对于涡动通量而言较大,忽略Fsd将为森林与大气之间净CO2交换量的计算带来误差.大气水热过程对Fs计算引起的误差包括3方面:空气温度变化引起的误差最大,比大气压强(P)的影响高1个数量级;水蒸气的影响在温暖湿润的夏季大于P的影响,但在寒冷干燥的冬季则相反;P的效应在全年均较低.基于ρc、cc和χc计算Fs分别平均高估CO2有效储存通量(Fs_E)8.5%、0.6%和0.1%.在通量计算过程中,建议选择对大气水热过程守恒的χc计算Fs.
Based on the measured data of 8-layer CO2 / H2O concentration profiles of the temperate deciduous broad-leaved forest fluxes in Mao’er Mountain, the effects of different concentration variables (density (ρc), mole fraction (cc) and mixing ratio The results showed that the storage volume of dry air in the control volume of the flux observation was not constant, and its fluctuation could cause the control volume of CO2 entry and exit, that is, the change of storage volume of dry air (Fsd) Fsd is relatively large with respect to the eddy flux at nighttime and diurnal conversion period and ignoring Fsd will bring errors to the calculation of net CO2 exchange between forest and atmosphere.According to the errors caused by atmospheric hydrothermal process on Fs calculation Including the three aspects: the air temperature caused the largest error, more than one-order of magnitude greater than the impact of atmospheric pressure (P); the effect of water vapor in the warm and humid summer is greater than P, but in the cold and dry winter is the opposite; P The effect is lower throughout the year.Fs calculated based on ρc, cc and χc respectively overestimated the effective storage flux (Fs_E) of 8.5%, 0.6% and 0.1% of CO2, respectively.In the process of flux calculation, The process of conservation χc computing Fs.