HR: 08:45h
AN: PP31C-04    [Abstracts]
TI: Weakening of the South Asian Monsoon Since 1600 A.D. from a Mt. Everest Ice Core
AU: * Kaspari, S D
EM: susan.kaspari@maine.edu
AF: Climate Change Institute, Department of Earth Sciences, University of Maine, 303 Bryand Global Sciences Center, Orono, ME 04469 United States
AU: Mayewski, P A
EM: paul.mayewski@maine.edu
AF: Climate Change Institute, Department of Earth Sciences, University of Maine, 303 Bryand Global Sciences Center, Orono, ME 04469 United States
AU: Mayewski, P A
EM: paul.mayewski@maine.edu
AF: Joint Key Laboratory of Cryosphere and Environment, Chinese Academy of Sciences, 260 Donggang W. Road, Lanzhou, 730000 China
AU: Kang, S
EM: shichang.kang@itpcas.ac.cn
AF: Joint Key Laboratory of Cryosphere and Environment, Chinese Academy of Sciences, 260 Donggang W. Road, Lanzhou, 730000 China
AU: Sneed, S B
EM: sharon.sneed@maine.edu
AF: Climate Change Institute, Department of Earth Sciences, University of Maine, 303 Bryand Global Sciences Center, Orono, ME 04469 United States
AU: Kreutz, K
EM: karl.kreutz@maine.edu
AF: Climate Change Institute, Department of Earth Sciences, University of Maine, 303 Bryand Global Sciences Center, Orono, ME 04469 United States
AU: Introne, D
EM: introne@maine.edu
AF: Climate Change Institute, Department of Earth Sciences, University of Maine, 303 Bryand Global Sciences Center, Orono, ME 04469 United States
AU: Hooke, R
EM: rhooke@verizon.net
AF: Climate Change Institute, Department of Earth Sciences, University of Maine, 303 Bryand Global Sciences Center, Orono, ME 04469 United States
AU: Maasch, K
EM: kirk@iceage.umeqs.maine.edu
AF: Climate Change Institute, Department of Earth Sciences, University of Maine, 303 Bryand Global Sciences Center, Orono, ME 04469 United States
AU: Hou, S
EM: shugui@lzb.ac.cn
AF: Joint Key Laboratory of Cryosphere and Environment, Chinese Academy of Sciences, 260 Donggang W. Road, Lanzhou, 730000 China
AU: Qin, D
EM: shichang.kang@itpcas.ac.cn
AF: Joint Key Laboratory of Cryosphere and Environment, Chinese Academy of Sciences, 260 Donggang W. Road, Lanzhou, 730000 China
AU: Ren, J
EM: jwren@lzb.ac.cn
AF: Joint Key Laboratory of Cryosphere and Environment, Chinese Academy of Sciences, 260 Donggang W. Road, Lanzhou, 730000 China
AB: A 108m high-resolution ice core drilled to bedrock from the East Rongbuk Col of Mt. Everest covers the last 1500 years. Analysis indicates a weakening of the Asian monsoon since 1600 AD. Empirical orthogonal function (EOF) analysis on the major ion (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^-, NO₃^-, SO₄^2-) and δD timeseries demonstrates that the Everest site is influenced by continental air masses associated with the Asian high pressure system and marine air masses associated with the South Asian monsoon. Everest Ca²⁺ is positively correlated with NCEP surface pressure from May-September over central Asia from 1948-2001, and Cl^- is negatively correlated. This indicates that when pressure is relatively higher over central Asia more continental air masses penetrate the Everest site, and conversely lower pressures is associated with more marine air masses. An inverse correlation of Everest δD and June-September NCEP precipitation rate from 1948-2001 confirms the results of previous studies that the amount effect is the primary control on δD in the Everest region (Kang et al., 2002, Tian et al., 2001; 2003). A trend towards increasing continental and decreasing marine air masses since 1600 suggests higher pressure over central Asia, and a reduction in monsoonal influence at the Everest site. Increasing δD and decreasing net mass balance since 1600 provides further support for a weakening of the South Asian monsoon over the Everest region. Proxy records from low elevation sites south of the Himalayas indicate a strengthening over the same time period (Anderson et al. 2002; von Rad et al., 1999; Wang et al., 2005). These regional differences are associated with higher pressure over Asia during summer and a southward shift in the mean summer position of the Intertropical Convergence Zone, as supported by a reduction in seasonal differences of insolation.
DE: 0368 Troposphere: constituent transport and chemistry
DE: 0724 Ice cores (4932)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 9320 Asia
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005