DOI: 10.1016/j.quascirev.2016.02.012
Scopus记录号: 2-s2.0-84959337141
论文题名: South Asian summer monsoon variability during the last ~54 kyrs inferred from surface water salinity and river run off proxies
作者: Gebregiorgis D. ; Hathorne E.C. ; Sijinkumar A.V. ; Nagender Nath B. ; Nürnberg D. ; Frank M.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2016
卷: 138 起始页码: 6
结束页码: 15
语种: 英语
英文关键词: Mixed layer
; South Asian monsoon
; Thermocline
; Upper ocean stratification
Scopus关键词: Runoff
; Stream flow
; Surface waters
; Temperature distribution
; Asian monsoon
; Asian summer monsoons
; Freshwater-induced stratifications
; Mixed layer
; Monsoon precipitation
; Sea surface salinity
; Thermocline temperature
; Upper ocean
; Atmospheric thermodynamics
; climate modeling
; Holocene
; intertropical convergence zone
; Last Glacial
; mixed layer
; monsoon
; oxygen isotope
; planktonic foraminifera
; precipitation (climatology)
; proxy climate record
; sea surface salinity
; seawater
; sediment core
; stratification
; summer
; thermocline
; upper ocean
; Andaman Sea
; Arabian Sea
; Indian Ocean
; South Asia
英文摘要: The past variability of the South Asian Monsoon is mostly known from records of wind strength over the Arabian Sea while high-resolution paleorecords from regions of strong monsoon precipitation are still lacking. Here, we present records of past monsoon variability obtained from sediment core SK 168/GC-1, which was collected at the Alcock Seamount complex in the Andaman Sea. We utilize the ecological habitats of different planktic foraminiferal species to reconstruct freshwater-induced stratification based on paired Mg/Ca and δ18O analyses and to estimate seawater δ18O (δ18Osw). The difference between surface and thermocline temperatures (δT) and δ18Osw (δδ18Osw) is used to investigate changes in upper ocean stratification. Additionally, Ba/Ca in G. sacculifer tests is used as a direct proxy for riverine runoff and sea surface salinity (SSS) changes related to monsoon precipitation on land. Our δδ18Osw time series reveals that upper ocean salinity stratification did not change significantly throughout the last glacial suggesting little influence of NH insolation changes. The strongest increase in temperature gradients between the mixed layer and the thermocline is recorded for the mid-Holocene and indicate the presence of a significantly shallower thermocline. In line with previous work, the δ18Osw and Ba/Ca records demonstrate that monsoon climate during the LGM was characterized by a significantly weaker southwest monsoon circulation and strongly reduced runoff. Based on our data the South Asian Summer Monsoon (SAM) over the Irrawaddyy strengthened gradually after the LGM beginning at ~18 ka. This is some 3 kyrs before an increase of the Ba/Ca record from the Arabian Sea and indicates that South Asian Monsoon climate dynamics are more complex than the simple N-S displacement of the ITCZ as generally described for other regions. Minimum δ18Osw values recorded during the mid-Holocene are in phase with Ba/Ca marking a stronger monsoon precipitation, which is consistent with model simulations. © 2016 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59627
Appears in Collections: 过去全球变化的重建
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作者单位: GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1-3, Kiel, Germany; Govt. College Kasaragod, Vidyanagar P.O, Kasaragod Dist., Kasaragod, Kerala, India; CSIR-National Institute of Oceanography, Dona Paula, Goa, India
Recommended Citation:
Gebregiorgis D.,Hathorne E.C.,Sijinkumar A.V.,et al. South Asian summer monsoon variability during the last ~54 kyrs inferred from surface water salinity and river run off proxies[J]. Quaternary Science Reviews,2016-01-01,138