Sources of uncertainty in eddy covariance ozone flux measurements made by dry chemiluminescence fast response analysers
Sources of uncertainty in eddy covariance ozone flux measurements made by dry chemiluminescence fast response analysers
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DOI：
10.5194/amt-3-163-2010
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发表时间：
2009-09
影响因子：
3.8
通讯作者：
J. Muller;C. Percival;M. Gallagher;D. Fowler;M. Coyle;E. Nemitz
中科院分区：
文献类型：
--
作者：
J. Muller;C. Percival;M. Gallagher;D. Fowler;M. Coyle;E. Nemitz
抽象的。我们提出了一个系统的涡动协方差臭氧通量的测量使用两个快速响应干化学发光分析仪的相互比较研究。2007年8月，在苏格兰爱丁堡附近的一个管理良好的草原上测量了臭氧沉积。介绍了这些分析仪的数据质量控制程序。绝对臭氧通量计算的基础上，使用三种不同的方法和结果进行了比较，两种分析仪的干化学发光分析仪的相对信号。它示出的通量计算所需的拟合分析仪校准参数中的误差提供了大量的不确定性通量的来源。计算方法本身的选择也可能构成通量的不确定性，因为三种方法计算的通量并不总是在误差范围内一致。这一发现强调了对可比数据集（例如通量网络）采用一致和严格方法的必要性。臭氧通量计算的方法之一，然后用来比较两个分析仪更详细。该系统分析仪比较显示，半小时通量值有时相差高达2倍，平均小时通量的差异范围为0至23%，平均日通量的误差为± 12%。分析仪的比较表明，在通量的协议是优秀的一些天，但有一个潜在的不确定性作为变量分析仪的性能和/或非线性灵敏度的结果。
Abstract. We present a systematic intercomparison study of eddy covariance ozone flux measurements made using two fast response dry chemiluminescence analysers. Ozone deposition was measured over a well characterised managed grassland near Edinburgh, Scotland, during August 2007. A data quality control procedure specific to these analysers is introduced. Absolute ozone fluxes were calculated based on the relative signals of the dry chemiluminescence analysers using three different methods and the results are compared for both analysers. It is shown that the error in the fitted analyser calibration parameters required for the flux calculations provides a substantial source of uncertainty in the fluxes. The choice of the calculation method itself can also constitute an uncertainty in the flux as the calculated fluxes by the three methods do not agree within error at all times. This finding highlights the need for a consistent and rigorous approach for comparable datasets, such as e.g. in flux networks. Ozone fluxes calculated by one of the methods were then used to compare the two analysers in more detail. This systematic analyser comparison reveals half-hourly flux values differing by up to a factor of two at times with the difference in mean hourly flux ranging from 0 to 23% with an error in the mean daily flux of ± 12%. The comparison of analysers shows that the agreement in fluxes is excellent for some days but that there is an underlying uncertainty as a result of variable analyser performance and/or non-linear sensitivity.