Characteristics of Relative Sampling Errors in Eddy Covariance Measurements and Their Application to Flux Measurement Aggregates

Using eddy covariance (EC) measurements, the exchanges of energy, water and carbon dioxide between the atmosphere and terrestrial ecosystem have been studied globally. EC measurements fundamentally operate under the hypotheses of stationarity and ergodicity, but these hypotheses are practically disturbed by various factors generated by varying atmospheric and land surface conditions. Therefore, the relative sampling error ε — a parameter quantifying the average convergence in a time series — is investigated to evaluate its capabilities as a quality parameter of EC measurements. Our results show that ε has a range from 5% to more than 100% and exhibits a close relationship to the integral turbulence characteristic (ITC), and it is a function of the atmospheric stability ζ. Therefore, we suggest that ε could represent a quality parameter of EC measurements and a weighting factor for statistical aggregates of the exchanges measured by EC measurements.