Examining the Energy Imbalance of Eddy-Covariance Measurements in a Tidal Wetland

Abstract

The energy balance of the Earth’s surface is crucial for understanding biosphere-atmosphere interactions. However, the energy imbalance observed in eddycovariance measurements indicates that our understanding and estimation of ecosystem dynamics remains incomplete. This issue is especially important for wetlands, which have an important role in global climate processes and exhibit the highest imbalances. In this study, we investigated the energy balance closure (EBC) in a restored tidal wetland. The EBC ratio before tidal restoration was 0.9, contrasting with a poor closure of 0.22 after tidal restoration. We applied filters based on friction velocity (u∗), wind direction and zenith angle, as well as accounting for soil heat storage. These filters improved closure before tidal restoration, but did not for the period after tidal restoration. Daily averaged fluxes enhanced closure up to 54%, suggesting the role of water storage, lateral water heat advection and an influence from large-scale eddies. Analysis of the Bowen ratio and the Priestley-Taylor parameter suggests influence of lateral heat advection after tidal restoration. Future research should include the challenging computations of these energy terms. These insights contribute to a deeper understanding of energy exchanges in tidal wetland environments and underlines important terms that should be taken into account, thereby aiding climate change studies and the management of wetland restoration.