气候变化领域集成服务门户(CCPortal): The end of the African humid period as seen by a transient comprehensive Earth system model simulation of the last 8000 years

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DOI	10.5194/cp-16-117-2020
	The end of the African humid period as seen by a transient comprehensive Earth system model simulation of the last 8000 years
	Dallmeyer A.; Claussen M.; Lorenz S.J.; Shanahan T.
发表日期	2020
ISSN	18149324
起始页码	117
结束页码	140
卷号	16 期号:1
英文摘要	Enhanced summer insolation during the early and mid-Holocene drove increased precipitation and widespread expansion of vegetation across the Sahara during the African humid period (AHP). While changes in atmospheric dynamics during this time have been a major focus of palaeoclimate modelling efforts, the transient nature of the shift back to the modern desert state at the end of this period is less well understood. Reconstructions reveal a spatially and temporally complex end of the AHP, with an earlier end in the north than in the south and in the east than in the west. Some records suggest a rather abrupt end, whereas others indicate a gradual decline in moisture availability. Here we investigate the end of the AHP based on a transient simulation of the last 7850 years with the comprehensive Earth system model MPI-ESM1.2. The model largely reproduces the time-transgressive end of the AHP evident in proxy data, and it indicates that it is due to the regionally varying dynamical controls on precipitation. The impact of the main rain-bringing systems, i.e. the summer monsoon and extratropical troughs, varies spatially, leading to heterogeneous seasonal rainfall cycles that impose regionally different responses to the Holocene insolation decrease. An increase in extratropical troughs that interact with the tropical mean flow and transport moisture to the western Sahara during the mid-Holocene delays the end of the AHP in that region. Along the coast, this interaction maintains humid conditions for a longer time than further inland. Drying in this area occurs when this interaction becomes too weak to sustain precipitation. In the lower latitudes of west Africa, where the rainfall is only influenced by the summer monsoon dynamics, the end of the AHP coincides with the retreat of the monsoonal rain belt. The model results clearly demonstrate that non-monsoonal dynamics can also play an important role in forming the precipitation signal and should therefore not be neglected in analyses of north African rainfall trends. © Author(s) 2020.
语种	英语
scopus关键词	atmospheric dynamics; climate conditions; climate modeling; heterogeneity; Holocene; humid tropics; monsoon; paleoclimate; precipitation (climatology); reconstruction; spatiotemporal analysis; vegetation type; Sahara
来源期刊	Climate of the Past
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/146754
作者单位	Land in the Earth System, Max Planck Institute for Meteorology, Bundesstrasse 53, Hamburg, 20146, Germany; Meteorological Institute, Centrum für Erdsystemforschung und Nachhaltigkeit (CEN), Universität Hamburg, Bundesstrasse 55, Hamburg, 20146, Germany; Ocean in the Earth System, Max Planck Institute for Meteorology, Bundesstrasse 53, Hamburg, 20146, Germany; University of Texas at Austin, Department of Geological Sciences, 1 University Station C9000, Austin, TX 78712, United States
推荐引用方式 GB/T 7714	Dallmeyer A.,Claussen M.,Lorenz S.J.,et al. The end of the African humid period as seen by a transient comprehensive Earth system model simulation of the last 8000 years[J],2020,16(1).
APA	Dallmeyer A.,Claussen M.,Lorenz S.J.,&Shanahan T..(2020).The end of the African humid period as seen by a transient comprehensive Earth system model simulation of the last 8000 years.Climate of the Past,16(1).
MLA	Dallmeyer A.,et al."The end of the African humid period as seen by a transient comprehensive Earth system model simulation of the last 8000 years".Climate of the Past 16.1(2020).