气候变化领域集成服务门户(CCPortal): The competing effects of terrestrial evapotranspiration and raindrop re-evaporation on the deuterium excess of continental precipitation

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DOI	10.1016/j.epsl.2021.117120
	The competing effects of terrestrial evapotranspiration and raindrop re-evaporation on the deuterium excess of continental precipitation
	Xia Z.; Winnick M.J.
发表日期	2021
ISSN	0012821X
卷号	572
英文摘要	The deuterium excess (d-excess) of precipitation, which tracks kinetic fractionations during water phase changes, has been used to trace the regions and conditions of oceanic moisture sources, in particular from polar ice-core records. Still, many observations suggest that precipitation d-excess varies significantly across terrestrial environments, both above and below the global average value 10. These variations are often interpreted to reflect either moisture recycling via terrestrial evapotranspiration or sub-cloud raindrop re-evaporation, respectively. Despite being frequently mentioned in literature, however, little work has been carried out to quantify these two competing effects on the widespread variations of d-excess. Here, we use a one-dimensional model of water vapor transport to interrogate the relative controls on d-excess of continental precipitation. We show that when the water vapor gradient is coupled with decreasing temperature, d-excess increases with net rainout and δ18O depletion along the model transect, while the magnitude of increase is controlled by the water balance, evaporation/transpiration ratio, and transport type. Raindrop re-evaporation functions as an additional flux of recycled moisture and further increases the d-excess downwind. Alternatively, when the water vapor gradient is coupled with decreasing relative humidity, d-excess may decrease along the model transect wherein upwind evapotranspiration is overwhelmed by local raindrop re-evaporation effects. This local effect becomes even stronger under a regime of turbulent eddy transport with high transpiration fractions, resulting in a pronounced decrease of d-excess without notable changes in δ18O. Finally, we demonstrate that model processes capture the isotopic variations in precipitation across the altitudinal gradient of the Andes as well as the South American low-level jet zone. Broadly, this study presents a novel framework for understanding the dynamical controls of precipitation d-excess and for linking spatial isotopic variations with ecohydrological fluxes and processes in both modern and paleo-environments. © 2021 Elsevier B.V.
关键词	deuterium excess evapotranspiration precipitation raindrop re-evaporation South America vapor transport model
英文关键词	Deuterium; Drops; Evaporation; Evapotranspiration; Moisture; Recycling; Water vapor; %moisture; Competing effects; Deuterium excess; Isotopic variations; Kinetic fractionations; Raindrop re-evaporation; South America; Terrestrial evapotranspiration; Vapor transport model; Water vapour; Precipitation (chemical)
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203343
作者单位	Department of Geosciences, University of Massachusetts Amherst, Amherst, MA, United States
推荐引用方式 GB/T 7714	Xia Z.,Winnick M.J.. The competing effects of terrestrial evapotranspiration and raindrop re-evaporation on the deuterium excess of continental precipitation[J],2021,572.
APA	Xia Z.,&Winnick M.J..(2021).The competing effects of terrestrial evapotranspiration and raindrop re-evaporation on the deuterium excess of continental precipitation.Earth and Planetary Science Letters,572.
MLA	Xia Z.,et al."The competing effects of terrestrial evapotranspiration and raindrop re-evaporation on the deuterium excess of continental precipitation".Earth and Planetary Science Letters 572(2021).