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| Titel |
Water vapour source impacts on oxygen isotope variability in tropical precipitation during Heinrich events |
| VerfasserIn |
S. C. Lewis, A. N. LeGrande, M. Kelley, G. A. Schmidt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 6, no. 3 ; Nr. 6, no. 3 (2010-06-01), S.325-343 |
| Datensatznummer |
250003546
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| Publikation (Nr.) |
 copernicus.org/cp-6-325-2010.pdf |
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| Zusammenfassung |
| Water isotope records such as speleothems provide extensive evidence of past
tropical hydrological changes. During Heinrich events, isotopic changes in
monsoon regions have been interpreted as implying a widespread drying through
the Northern Hemisphere tropics and an anti-phased precipitation response in
the south. Here, we examine the sources of this variability using a water
isotope-enabled general circulation model, Goddard Institute for Space
Studies ModelE. We incorporate a new suite of vapour source distribution
tracers to help constrain the impact of precipitation source region changes
on the isotopic composition of precipitation and to identify nonlocal amount
effects. We simulate a collapse of the North Atlantic meridional overturning
circulation with a large freshwater input to the region as an idealised
analogue to iceberg discharge during Heinrich events. An increase in monsoon
intensity, defined by vertical wind shear, is modelled over the South
American domain, with small decreases simulated over Asia. Simulated isotopic
anomalies agree well with proxy climate records, with lighter isotopic values
simulated over South America and enriched values across East Asia. For this
particular abrupt climate event, we identify which climatic change is most
likely linked to water isotope change – changes in local precipitation
amount, monsoon intensity, water vapour source distributions or precipitation
seasonality. We categorise individual sites according to the climate
variability that water isotope changes are most closely associated with, and
find that the dominant isotopic controls are not consistent across the
tropics – simple local explanations, in particular, fall short of explaining
water isotope variability at all sites. Instead, the best interpretations
appear to be site specific and often regional in scale. |
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