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DOI	10.1029/2018JD029550
	The Effects of Surface Heterogeneity Scale on the Flux Imbalance under Free Convection
	Zhou, Yanzhao; Li, Dan; Li, Xin
通讯作者	Li, X (通讯作者)
发表日期	2019
EISSN	2169-8996
起始页码	8424
结束页码	8448
卷号	124 期号:15
英文摘要	It is well known that the available energy (i.e., the net radiation minus the ground heat flux) is often 10-30% larger than the sum of turbulent fluxes measured by the eddy-covariance method. Although field observations and previous large-eddy simulation studies have shown that surface heterogeneity can induce flux imbalance, the relationship between the flux imbalance magnitude and the surface heterogeneity scale remains to be investigated in more detail. Here we examine the flux imbalance over landscapes characterized by different surface heterogeneity scales in a dry freely convective boundary layer. We reveal that the flux imbalance initially increases with increasing surface heterogeneity scale. However, when the surface heterogeneity scale becomes larger than the boundary layer height, the surface starts to behave locally homogeneous, which leads to a lower flux imbalance. Based on large-eddy simulation results, we propose a conceptual model to explain how the domain average flux imbalance is influenced by surface heterogeneity. The flux imbalance is found to be controlled by the ratio of the boundary layer height to the Obukhov length (-z(i)/L), the integral length scale of vertical velocity (l(w)), the mean horizontal speed (U), and the time averaging interval (T). Among these four variables, l(w) determines the size of turbulent coherent structures (i.e., large eddies), whereas -z(i)/L affects the form of these large eddies. Meanwhile, the U and T determine how many these large eddies can be sampled by the eddy covariance. This finding indicates that it may be possible to diagnose the flux imbalance using these four variables under convective conditions.
关键词	ENERGY-BALANCE CLOSURE LARGE-EDDY SIMULATION PLANETARY BOUNDARY-LAYER LAND-SURFACE HEAT-FLUX PART I LONG-TERM IMPACT TEMPERATURE SIMILARITY
英文关键词	convective boundary layer; flux imbalance; large eddy simulation; surface heterogeneity scale
语种	英语
WOS研究方向	Meteorology & Atmospheric Sciences
WOS类目	Meteorology & Atmospheric Sciences
WOS记录号	WOS:000482475000004
来源期刊	JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/259483
推荐引用方式 GB/T 7714	Zhou, Yanzhao,Li, Dan,Li, Xin. The Effects of Surface Heterogeneity Scale on the Flux Imbalance under Free Convection[J]. 中国科学院青藏高原研究所,2019,124(15).
APA	Zhou, Yanzhao,Li, Dan,&Li, Xin.(2019).The Effects of Surface Heterogeneity Scale on the Flux Imbalance under Free Convection.JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES,124(15).
MLA	Zhou, Yanzhao,et al."The Effects of Surface Heterogeneity Scale on the Flux Imbalance under Free Convection".JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 124.15(2019).