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- Title
Enlarged Nonclosure of Surface Energy Balance With Increasing Atmospheric Instabilities Linked to Changes in Coherent Structures.
- Authors
Gao, Zhongming; Liu, Heping; Chen, Xingyuan; Huang, Maoyi; Missik, Justine E. C.; Yao, Jingyu; Arntzen, Evan; Mcfarland, Douglas P.
- Abstract
The nonclosure of surface energy balance remains an outstanding problem in eddy covariance (EC) measurements of land‐surface fluxes of heat, water vapor, and CO2. Here data collected from an EC tower over a semiarid sagebrush ecosystem indicate that under unstable atmospheric conditions, the nonclosure becomes increased with increasing instability, consistent with many other studies. It is demonstrated that the increased nonclosure is not caused by the inadequate sampling of large‐scale turbulent motions using a 30‐min averaging interval, though the scales of turbulent motions dominating sensible and latent heat fluxes become enlarged with increasing instability. Quadrant analysis is then used to reveal that the flux contributions from ejections remain nearly constant with increasing instability, whereas the flux contributions from sweeps are reduced and their time fractions increase. Our results imply that the increased nonclosure of surface energy balance is associated with changes in turbulent structures including their dominant time scales and flux contributions of ejections and sweeps as the atmospheric instability increases, which require further studies using vertically distributed observations and/or large eddy simulations. Key Points: The nonclosure of the surface energy balance increases with the increasing atmospheric instabilityThe increased nonclosure is not caused by the inadequate sampling of large‐scale turbulent motionsThe scales of turbulent eddies dominating fluxes change as the atmospheric instability increases
- Subjects
SURFACE energy; BIOENERGETICS; ACQUISITION of data; CLIMATOLOGY; METEOROLOGY
- Publication
Journal of Geophysical Research. Atmospheres, 2020, Vol 125, Issue 14, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2020JD032889