气候变化领域集成服务门户(CCPortal): Atmospheric controls on precipitation isotopes and hydroclimate in high-elevation regions in Eastern Africa since the Last Glacial Maximum

CCPortal

DOI	10.1016/j.epsl.2021.116984
	Atmospheric controls on precipitation isotopes and hydroclimate in high-elevation regions in Eastern Africa since the Last Glacial Maximum
	Garelick S.; Russell J.M.; Dee S.; Verschuren D.; Olago D.O.
发表日期	2021
ISSN	0012821X
卷号	567
英文摘要	Tropical Africa experienced large changes in hydroclimatic conditions since the Last Glacial Maximum (LGM), ∼26.5 to 19 thousand years (ka or kyr) ago. The hydrogen isotopic composition of fossil leaf waxes (δDwax), assumed to record past variations in the hydrogen isotopic composition of precipitation (δDprecip), is increasingly being used to study past hydroclimatic change in Africa, and are commonly interpreted to reflect variation in the amount of precipitation through time (i.e., the amount effect). Although there are now many such δDprecip records from tropical Africa, there are few robust δDprecip records from easternmost equatorial Africa of sufficient length and resolution to evaluate the mechanisms governing hydroclimate variation during and since the LGM. We produced a new δDprecip record based on analyses of δDwax in sediment cores collected from Lake Rutundu, situated at an elevation of 3,078 meters above sea level (m asl) on Mt. Kenya. This record displays large variations in δDprecip corresponding with known climate events over the past 25 kyr, including D-enrichment during the Heinrich 1 stadial (H1) and the Younger Dryas (YD), and D-depletion during the Holocene portion of the African Humid Period (AHP). We also observe D-depletion during the LGM relative to the late Holocene, which, considering the amount effect, could be interpreted to imply that LGM climate conditions were wetter than today. However, because other hydroclimate proxies at this site indicate a drier LGM climate at Lake Rutundu, and since precipitation isotopes at this high-elevation site are likely influenced by different processes than at low elevations, we used a single-column Rayleigh distillation model to evaluate temperature and altitude-related effects on high-elevation δDprecip. This revealed that a change in the temperature lapse rate exerts strong control on δDprecip in this high-elevation setting, and that a steeper lapse rate could explain the observed D-depletion during the LGM at our site. Comparison of the Lake Rutundu δDprecip record with other leaf-wax based δDprecip records from East Africa indicates that changes in the meridional precipitation gradient associated with the mean annual position and intensity of the tropical rain belt, in turn driven by precessional insolation forcing, were likely a primary control on East African hydroclimate over the past 25 kyr, thereby contributing to overall regional drying during the LGM. © 2021 Elsevier B.V.
关键词	East Africa high-elevation climate hydrogen isotopes lapse rate precipitation
英文关键词	Distillation; Glacial geology; Isotopes; Lakes; Precipitation (chemical); Precipitation (meteorology); Sea level; Tropics; Amount effects; Atmospheric controls; East Africa; High elevation; High-elevation climate; Hydroclimates; Hydrogen isotope; Hydrogen isotopic composition; Lapse rate; Last Glacial Maximum; Hydrogen; atmospheric chemistry; climate variation; Heinrich event; Holocene; hydrogen isotope; hydrometeorology; isotopic composition; Last Glacial Maximum; paleoclimate; precipitation quality; Younger Dryas; East Africa; Kenya; Lake Rutundu; Meru
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/203098
作者单位	Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, United States; Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, United States; Department of Biology, Limnology Unit, Ghent University, Ghent, Belgium; Department of Geology, University of Nairobi, Nairobi, Kenya; Institute for Climate Change and Adaptation, University of Nairobi, Nairobi, Kenya
推荐引用方式 GB/T 7714	Garelick S.,Russell J.M.,Dee S.,et al. Atmospheric controls on precipitation isotopes and hydroclimate in high-elevation regions in Eastern Africa since the Last Glacial Maximum[J],2021,567.
APA	Garelick S.,Russell J.M.,Dee S.,Verschuren D.,&Olago D.O..(2021).Atmospheric controls on precipitation isotopes and hydroclimate in high-elevation regions in Eastern Africa since the Last Glacial Maximum.Earth and Planetary Science Letters,567.
MLA	Garelick S.,et al."Atmospheric controls on precipitation isotopes and hydroclimate in high-elevation regions in Eastern Africa since the Last Glacial Maximum".Earth and Planetary Science Letters 567(2021).