LAUSR

The continuous measurement of H 2 O and CO 2 fluxes using the eddy covariance (EC) technique is still challenging for forests in complex terrain because of large amounts of wet canopy evaporation ( E WC ), which occur during and following rain events when the EC systems rarely work correctly, and the horizontal advection of CO 2 generated at night. We propose new techniques for gap-filling and partitioning of the H 2 O and CO 2 fluxes: (1) a model-stats hybrid method (MSH) and (2) a modified moving point test method (MPT m ). The former enables the recovery of the missing E WC in the traditional gap-filling method and the partitioning of the evapotranspiration (ET) into transpiration and (wet canopy) evaporation. The latter determines the friction velocity ( u * ) threshold based on an iterative approach using moving windows for both time and u * , thereby allowing not only the nighttime CO 2 flux correction and partitioning but also the assessment of the significance of the CO 2 drainage. We tested and validated these new methods using the datasets from two flux towers, which are located at forests in hilly and complex terrains. The MSH reasonably recovered the missing E WC of 16 ~ 41 mm year −1 and separated it from the ET (14 ~ 23 % of the annual ET). The MPT m produced consistent carbon budgets using those from the previous research and diameter increment, while it has improved applicability. Additionally, we illustrated certain advantages of the proposed techniques, which enables us to understand better how ET responses to environmental changes and how the water cycle is connected to the carbon cycle in a forest ecosystem.