It is now accepted that large-scale turbulent eddies impact the widely reported non-closure of the surface energy balance when latent and sensible heat fluxes are measured using the eddy covariance method in the atmospheric surface layer (ASL). However, a mechanistic link between large eddies and non-closure of the surface energy balance remains a subject of inquiry. Here, measured 10 Hz time series of vertical velocity, air temperature, and water vapor density collected in the ASL are analyzed for conditions where entrainment and/or horizontal advection separately predominate. The series are decomposed into small- and large- eddies based on a frequency cutoff and their contributions to turbulent fluxes are analyzed. Phase difference between vertical velocity and water vapor density associated with large eddies reduces latent heat fluxes, especially in conditions where advection prevails. Enlarged phase difference of large eddies linked to entrainment or advection occurrence leads to increased residuals of the surface energy balance.
Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman, Washington, United States of America;Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman, Washington, United States of America;Author to whom any correspondence should be addressed.;Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, United States of America;Department of Civil and Environmental Engineering, Duke University, Durham, North Carolina 27708, United States of America;Bayreuth Center of Ecology and Environmental Research, University of Bayreuth, Bayreuth, Bavaria, Germany
Recommended Citation:
Zhongming Gao,Heping Liu,Gabriel G Katul,et al. Non-closure of the surface energy balance explained by phase difference between vertical velocity and scalars of large atmospheric eddies[J]. Environmental Research Letters,2017-01-01,12(3)