globalchange  > 过去全球变化的重建
DOI: 10.1016/j.palaeo.2013.12.007
论文题名:
The effects of solar irradiation changes on the migration of the Congo Air Boundary and water levels of paleo-Lake Suguta, Northern Kenya Rift, during the African Humid Period (15-5ka BP)
作者: Junginger A.; Roller S.; Olaka L.A.; Trauth M.H.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2014
卷: 396
起始页码: 1
结束页码: 16
语种: 英语
英文关键词: African Humid Period ; Congo Air Boundary ; East African Rift System ; Suguta Valley
英文摘要: The water-level record from the 300. m deep paleo-lake Suguta (Northern Kenya Rift) during the African Humid Period (AHP, 15-5. ka BP) helps to explain decadal to centennial intensity variations in the West African Monsoon (WAM) and the Indian Summer Monsoon (ISM). This water-level record was derived from three different sources: (1) grain size variations in radiocarbon dated and reservoir corrected lacustrine sediments, (2) the altitudes and ages of paleo-shorelines within the basin, and (3) the results of hydro-balance modeling, providing important insights into the character of water level variations (abrupt or gradual) in the amplifier paleo-Lake Suguta. The results of these comprehensive analyses suggest that the AHP highstand in the Suguta Valley was the direct consequence of a northeastwards shift in the Congo Air Boundary (CAB), which was in turn caused by an enhanced atmospheric pressure gradient between East Africa and India during a northern hemisphere insolation maximum. Rapidly decreasing water levels of up to 90. m over less than a hundred years are best explained by changes in solar irradiation either reducing the East African-Indian atmospheric pressure gradient and preventing the CAB from reaching the study area, or reducing the overall humidity in the atmosphere, or a combination of both these effects. In contrast, although not well documented in our record we hypothesize a gradual end of the AHP despite an abrupt change in the source of precipitation when a decreasing pressure gradient between Asia and Africa prevented the CAB from reaching the Suguta Valley. The abruptness was probably buffered by a contemporaneous change in precession producing an insolation maximum at the equator during October. Whether or not this is the case, the water-level record from the Suguta Valley demonstrates the importance of both orbitally-controlled insolation variations and short-term changes in solar irradiation as factors affecting the significant water level variations in East African rift lakes. © 2013 Elsevier B.V.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69455
Appears in Collections:过去全球变化的重建

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作者单位: Institute for Earth and Environmental Sciences, University of Potsdam, Karl-Liebknecht-Str. 24, Am Mühlenberg 3, D-14476 Potsdam, Germany; DFG Graduate School on Shaping the Earth's Surface in a Variable Environment, University of Potsdam, Karl-Liebknecht-Str. 24, 14476 Potsdam, Germany; Senckenberg Forschungsinstitut und Naturkundemuseum Frankfurt, Senckenberganlage 25, 60325 Frankfurt, Germany; Geology Department, University of Nairobi, P.O. BOX 30197, Nairobi, Kenya

Recommended Citation:
Junginger A.,Roller S.,Olaka L.A.,et al. The effects of solar irradiation changes on the migration of the Congo Air Boundary and water levels of paleo-Lake Suguta, Northern Kenya Rift, during the African Humid Period (15-5ka BP)[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2014-01-01,396
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