True eddy accumulation – Part 1: Solutions to the problem of non-vanishing mean vertical wind velocity

Abstract. The true eddy accumulation (TEA) method provides direct measurements of ecosystem-level turbulent fluxes for a wide range atmospheric constituents. TEA utilizes conditional sampling to overcome the requirement fast sensor response demanded by state-of-the-art covariance (EC) method. is formulated under assumption ideal conditions with zero mean vertical wind velocity during averaging interval. However, this idealization rarely met field conditions. Additionally, unlike in EC, cannot be imposed post-processing due real-time nature and absence high-frequency scalar. Consequently, measured are biased non-turbulent advective term that scales scalar concentration. Here, we explore magnitude potential ways minimize or remove it. We propose new formulation calculate minimizes bias term. shows error constrained w‾/|w|‾ when stationarity criterion fulfilled. w velocity, overbar denotes time averaging. shown dependent on asymmetry transport, represented coefficient αc. Two methods estimating αc proposed: probabilistic treatment transport utilizing similarity. show how other formulas calculating flux linked different corrections numerical simulation. avoids dependence background This result increases confidence applying measuring particularly relevant scalars large concentration small flux. paper Part 1 two-part series accumulation.