Surface-Energy-Balance Closure over Land: A Review
- PDF / 1,770,043 Bytes
- 32 Pages / 439.37 x 666.142 pts Page_size
- 45 Downloads / 183 Views
Surface‑Energy‑Balance Closure over Land: A Review Matthias Mauder1 · Thomas Foken2 · Joan Cuxart3 Received: 25 November 2019 / Accepted: 2 May 2020 © The Author(s) 2020
Abstract Quantitative knowledge of the surface energy balance is essential for the prediction of weather and climate. However, a multitude of studies from around the world indicate that the turbulent heat fluxes are generally underestimated using eddy-covariance measurements, and hence, the energy balance is not closed. This energy-balance-closure problem, which has been heavily covered in the literature for more than 25 years, is the topic of the present review, in which we provide an overview of the potential reason for the lack of closure. We demonstrate the effects of the diurnal cycle on the energy balance closure, and address questions with regard to the partitioning of the energy balance residual between the sensible and the latent fluxes, and whether the magnitude of the flux underestimation can be predicted based on other variables typically measured at micrometeorological stations. Remaining open questions are discussed and potential avenues for future research on this topic are laid out. Integrated studies, combining multi-tower experiments and scale-crossing, spatially-resolving lidar and airborne measurements with high-resolution large-eddy simulations, are considered to be of critical importance for enhancing our understanding of the underlying transport processes in the atmospheric boundary layer. Keywords Eddy covariance · Energy balance closure · Large-eddy simulation · Secondary circulations · Surface energy balance
1 Introduction 1.1 The Surface Energy Balance and Its Relevance The surface energy balance (SEB) is an essential cornerstone of any theoretical description of the Earth’s climate system. It can be assessed locally on the ecosystem scale if the turbulent heat fluxes, the soil heat flux and net radiation are measured independently, * Matthias Mauder [email protected] 1
Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, 82467 Garmisch‑ Partenkirchen, Germany
2
Bayreuth Center of Ecology and Environmental Research, University of Bayreuth, 95440 Bayreuth, Germany
3
Department of Physics, University of the Balearic Islands, 07122 Palma, Mallorca, Spain
13
Vol.:(0123456789)
M. Mauder et al.
H + 𝜆E + G + Imb = Rn ,
(1)
where H is the sensible heat flux, λE is the latent heat flux, both of which are most directly measured using the eddy-covariance (EC) technique, G is the soil heat flux at the surface, which can be quantified by a combination of heat-flux plates, soil temperature, and soil water content sensors (energy storage in the canopy can potentially also be included here), and Rn is net radiation, which is ideally measured by a high-quality four-component net radiometer. The imbalance (Imb) is considered as the total contribution of neglected effects and uncertainties. All terms on the left-hand side of Eq. 1 are defined positive for transferring energy away fro
Data Loading...
