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| Titel |
Hydrological and Vegetation Shifts in the Equatorial Sulawesi since the Last Glacial Maximum: Perspectives from Hydrogen and Carbon Isotopes of Terrestrial Leaf Wax Compounds |
| VerfasserIn |
Satrio Wicaksono, James Russell, Ann Holbourn, Wolfgang Kuhnt |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094008
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| Publikation (Nr.) |
 EGU/EGU2014-9283.pdf |
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| Zusammenfassung |
| The Indo-Pacific Warm Pool (IPWP) is a major epicenter of the tropical convective
activity that drives both the Walker and Hadley circulations. The island of Sulawesi is
situated at the heart of the Maritime Continent within the IPWP, and despite the
region’s importance, published proxy records and numerical simulations of convection
and precipitation patterns from Sulawesi and across the Maritime Continent since
the Last Glacial Maximum (LGM) display some substantial disagreement. Today,
precipitation over Sulawesi is strongly influenced by variations in topography and wind
pattern, which include land-sea breezes, orographically-forced winds, and monsoonal
winds related to the seasonal migration of the Intertropical Convergence Zone. To
better understand the interplay between such variations and high latitude climate
dynamics during the last deglaciation, we developed high resolution records of the
deuterium isotopic composition of terrestrial leaf waxes (long-chain n-alkanoic acids;
δDwax) from a marine core (3.63 ºS, 119.36 ºE, water depth: 688 m) retrieved 10 km
west of Sulawesi in close proximity to a major river delta. At low latitudes, δDwax
has been used to reconstruct the δD of catchment-integrated precipitation, often
interpreted as an indicator of regional rainfall amounts and large-scale convective
activity.
Our record displays relatively depleted values during the height of LGM, followed by a
gradual enrichment that reached its peak (up to 10oenrichment) during the Younger Dryas
(YD). Following the YD, δDwax becomes more depleted into the Holocene, reaching values
nearly identical to the LGM. The deglacial pattern observed in our δDwax, derived from a
predominantly high-altitude catchment in the southwestern arm of Sulawesi, is similar to that
of δDwax record from Lake Towuti (2.5 ºS, 121.5 ºE, surface elevation: 319 m) in the
southeastern arm of Sulawesi. The synoptic deglacial shifts seen in both catchments
demonstrate that the equatorial Maritime Continent hydrological cycle is sensitive to
Northern Hemisphere high-latitude climate events. Despite the lowering of global
temperature during both the LGM and YD, the contrasting precipitation signals between
the two events over Sulawesi also suggest that different climatic forcing and/or
propagation mechanisms might have operated at different time scales. In addition, we will
measure carbon isotopes of terrestrial leaf wax compounds (δ13Cwax) to investigate
changes in local terrestrial vegetation assemblages and, by inference, the climate
in which they grew. Covariation between our δDwax and δ13Cwax records may
corroborate our interpretation of δDwax as a robust tropical paleoprecipitation proxy. |
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