Seasonal and Diurnal Variations in the Priestley-Taylor Coefficient for a Large Ephemeral Lake

	Seasonal and Diurnal Variations in the Priestley-Taylor Coefficient for a Large Ephemeral Lake
	Gan, Guojing; Liu, Yuanbo; Pan, Xin; Zhao, Xiaosong; Li, Mei; Wang, Shigang
刊名	WATER
	2020
卷号	12 期号:3
英文摘要	The Priestley-Taylor equation (PTE) is widely used with its sole parameter (alpha) set as 1.26 for estimating the evapotranspiration (ET) of water bodies. However, variations in alpha may be large for ephemeral lakes. Poyang Lake, which is the largest freshwater lake in China, is water-covered and wetland-covered during its high-water and low-water periods, respectively, over a year. This paper examines the seasonal and diurnal variations in alpha using eddy covariance observation data for Poyang Lake. The results show that alpha = 1.26 is overall feasible for both periods at daily and subdaily scales. No obvious seasonal trend was observed, although the standard deviation in alpha for the wetland was larger than that for the water surface. The mean bias in evaporation estimations using the PTE was less than 5 W.m(-2) during both periods, and the root mean square errors were much smaller than the average evaporation measurements at daily scale. U-shaped diurnal patterns of alpha were found during both periods, due partly to the negative correlation between alpha and the available energy (A). Compared to the vapor pressure deficit (VPD), wind speed (u) exerts a larger contribution to these variations. In addition, u is positively correlated with alpha during both periods, however, VPD was positively and negatively correlated with alpha during the high-water and low-water periods, respectively. Subdaily alpha exhibited contrasting clusters in the (u, VPD) plane under the same available energy ranges. Our study highlights the seasonal and diurnal course of alpha and suggests the careful use of PTE at subdaily scales.
内容类型	期刊论文
源URL	[http://159.226.73.51/handle/332005/20026]
专题	中国科学院南京地理与湖泊研究所
推荐引用方式 GB/T 7714	Gan, Guojing,Liu, Yuanbo,Pan, Xin,et al. Seasonal and Diurnal Variations in the Priestley-Taylor Coefficient for a Large Ephemeral Lake[J]. WATER,2020,12(3).
APA	Gan, Guojing,Liu, Yuanbo,Pan, Xin,Zhao, Xiaosong,Li, Mei,&Wang, Shigang.(2020).Seasonal and Diurnal Variations in the Priestley-Taylor Coefficient for a Large Ephemeral Lake.WATER,12(3).
MLA	Gan, Guojing,et al."Seasonal and Diurnal Variations in the Priestley-Taylor Coefficient for a Large Ephemeral Lake".WATER 12.3(2020).