DOI: 10.1016/j.gloplacha.2013.09.005
论文题名: Hydrological constraints of paleo-Lake Suguta in the Northern Kenya Rift during the African Humid Period (15-5kaBP)
作者: Junginger A. ; Trauth M.H.
刊名: Global and Planetary Change
ISSN: 0921-8185
出版年: 2013
卷: 111 起始页码: 174
结束页码: 188
语种: 英语
英文关键词: African Humid Period
; Congo Air Boundary
; East African Rift System
; Suguta Valley
Scopus关键词: Congo Air Boundary
; East African Rift
; Humid periods
; Intertropical convergence zone
; Lacustrine sediments
; Northern hemisphere
; Suguta Valley
; Water-level fluctuation
; Atmospheric pressure
; Geologic models
; Incident solar radiation
; Lakes
; Landforms
; Pressure gradient
; Rain
; Water levels
; Hierarchical systems
; climate change
; humid environment
; intertropical convergence zone
; lacustrine deposit
; Northern Hemisphere
; numerical model
; paleolimnology
; precipitation (climatology)
; rainfall
; water level
; Kenya
; Rift Valley
; Suguta Valley
英文摘要: During the African Humid Period (AHP, 15-5kaBP) an almost 300m deep paleo-lake covering 2200km2 developed in the Suguta Valley, in the Northern Kenya Rift. Data from lacustrine sediments and paleo-shorelines indicate that a large paleo-lake already existed by 13.9kaBP, and record rapid water level fluctuations of up to 100m within periods of 100years or less, and a final lowstand at the end of the AHP (5kaBP). We used a hydro-balance model to assess the abruptness of these water level fluctuations and identify their causes. We observed that fluctuations within the AHP were caused by abrupt changes in precipitation of 26-40%. Despite the absence of continuous lacustrine data documenting the onset of the AHP in the Suguta Valley, we conclude from the hydro-balance model that only an abrupt onset to the AHP, prior to 14.8kaBP, could have led to high water levels recorded. The modeling results suggest that the sudden increase in rainfall was the direct consequence of an eastward migration of the Congo Air Boundary (CAB), caused by an enhanced atmospheric pressure gradient between East Africa and southern Asia during a northern hemisphere (NH) summer insolation maximum. In contrast, the end of the AHP must have been gradual despite an abrupt change in the source of precipitation when a decreasing pressure gradient between Asia and Africa prevented the CAB from reaching the study area. This abruptness was probably buffered by a contemporaneous change in precession producing an insolation maximum at the equator during September-October. This change would have meant that the only rain source was the Intertropical Convergence Zone (ITCZ), which would have carried a greater amount of moisture during the short rainy season thus slowing the fall in water level over a period of about 1000years in association with the reduction in insolation. The results of this study provide an indication of the amount of time available for humans in north-eastern Africa to adapt in response to a changing climate, from hunting and gathering to farming and herding. © 2013 Elsevier B.V. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885720214&doi=10.1016%2fj.gloplacha.2013.09.005&partnerID=40&md5=11c29393d4388f5d144eecdad01dfd9d
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/11091
Appears in Collections: 全球变化的国际研究计划
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作者单位: Institute for Earth and Environmental Science, University of Potsdam, Karl-Liebknecht-Str. 24, 14476 Potsdam, Germany
Recommended Citation:
Junginger A.,Trauth M.H.. Hydrological constraints of paleo-Lake Suguta in the Northern Kenya Rift during the African Humid Period (15-5kaBP)[J]. Global and Planetary Change,2013-01-01,111.