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| Titel |
Similar speleothem δ18O signals indicating diverging climate variations in inland central Asia and monsoonal south Asia during the Holocene |
| VerfasserIn |
Liya Jin, Xiaojian Zhang |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152772
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| Publikation (Nr.) |
 EGU/EGU2017-17654.pdf |
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| Zusammenfassung |
| High-resolution and precisely dated speleothem oxygen isotope (δ18O) records from Asia
have provided key evidence for past monsoonal changes. It is found that δ18O records of
stalagmites from Kesang Cave (42∘52′N, 81∘45′E, Xinjiang, China) in inland central Asia
were very similar to those from Qunf Cave (17∘10′N, 54∘18′E, southern Oman) in South
Asia, shifting from light to heavy throughout the Holocene, which was regarded as a signal
that strong Asian summer monsoon (ASM) may have intruded into the Kesang Cave
site and/or adjacent areas in inland central Asia to produce heavy rainfall during
the high insolation times (e.g. the early Holocene). However, this is in contrast to
conclusions based on other Holocene proxy records and modeling simulations, showing
a persistent wetting trend in arid central Asia during the Holocene with a dryer
condition in the early Holocene and the wettest condition in the late Holocene.
With an analysis of model-proxy data comparison, we revealed a possible physical
mechanism responsible for the Holocene evolution of moisture/precipitation in Asian
summer monsoon (ASM)-dominated regions and that in the inland central Asia.
It is revealed that a recurrent circumglobal teleconnection (CGT) pattern in the
summertime mid-latitude circulation of the Northern Hemisphere was closely related to the
ASM and the climate of inland central Asia, acting as a bridge linking the ASM to
insolation, high-latitude forcing (North Atlantic sea surface temperature (SST)), and
low-latitude forcing (tropical Ocean SST). Also, the CGT influence speleothem δ18O
values in South Asia via its effect on the amount of precipitation. In addition, the
moisture source from the Indian Ocean is associated with relatively high δ18O values
compared with that from the North Atlantic Ocean, leading to increased precipitation
δ18O values. Hence, the CGT has probably been the key factor responsible for the
in-phase relationship in speleothem δ18O values (Kesang Cave and Qunf Cave), but
out-of-phase relationship in moisture/precipitation evolutions between inland central
Asia and the ASM region during the Holocene. In addition, since boreal winter
(December–January–February, DJF) precipitation in northwestern China (a part of the core
zone in inland central Asia) during the Holocene has been revealed to contribute
a great deal to moisture evolution in inland central Asia, and the changes in the
seasonal cycle of incoming solar radiation driven by Earth’s orbital changes have
probably played an important role in the out-of-phase relationship in the moisture
evolution between the inland central Asia and ASM regions during the Holocene. |
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