A comprehensive filtering scheme for high-resolution estimation of the water balance components from high-precision lysimeters

摘要

Large weighing lysimeters are currently the most precise method to directlymeasure all components of the terrestrial water balance in parallel via thebuilt-in weighing system. As lysimeters are exposed to several externalforces such as management practices or wind influencing the weighing data,the calculated fluxes of precipitation and evapotranspiration can be alteredconsiderably without having applied appropriate corrections to the raw data.Therefore, adequate filtering schemes for obtaining most accurate estimates ofthe water balance components are required. In this study, we use data fromthe TERENO (TERrestrial ENvironmentalObservatories) SoilCan research site in Bad Lauchst?dt to develop a comprehensivefiltering procedure for high-precision lysimeter data, which is designed todeal with various kinds of possible errors starting from the elimination oflarge disturbances in the raw data resulting e.g., from management practicesall the way to the reduction of noise caused e.g., by moderate wind.Furthermore, we analyze the influence of averaging times and thresholdsrequired by some of the filtering steps on the calculated water balance andinvestigate the ability of two adaptive filtering methods (the adaptivewindow and adaptive threshold filter (AWAT filter; Peters et al., 2014), anda new synchro filter applicable to the data from a set of several lysimeters)to further reduce the filtering error. Finally, we take advantage of the datasets of all 18 lysimeters running in parallel at the Bad Lauchst?dt site toevaluate the performance and accuracy of the proposed filtering scheme. Forthe tested time interval of 2 months, we show that the estimation of thewater balance with high temporal resolution and good accuracy is possible.The filtering code can be downloaded from the journal website as Supplementto this publication.