Multiple tree-ring chronologies (ring width, delta C-13 and delta O-18) reveal dry and rainy season signals of rainfall in Indonesia

• Climatic hazards, such as severe droughts and floods, affect extensive areas across monsoon Asia and can have profound impacts on the populations of that region. The area surrounding Indonesia, including large portions of the eastern Indian Ocean and Java Sea, plays a key role in the global climate system because of the enormous heat and moisture exchange that occurs between the ocean and atmosphere there. Here, we evaluate the influence of rainfall variability on multiple tree-ring parameters of teak (Tectona grandis) trees growing in a lowland rain forest in Central Java (Indonesia). We assess the potential of, annually resolved, tree-ring width, stable carbon (delta C-13) and oxygen (delta O-18) isotope records to improve our understanding of the Asian monsoon variability. Climate response analysis with regional, monthly rainfall data reveals that all three tree-ring parameters are significantly correlated to rainfall, albeit during different monsoon seasons. Precipitation in the beginning of the rainy season (Sep-Nov) is important for tree-ring width, confirming previous studies. Compared to ring width, the stable isotope records possess a higher degree of common signal, especially during portions of the peak rainy season (delta C-13: Dec-May; delta O-18: Nov-Feb) and are negatively correlated to rainfall. In addition, tree-ring delta O-18 also responds positively to peak dry season rainfall, although the delta O-13 rainy season signal is stronger and more time-stable. The correlations of opposite sign reflect the distinct seasonal contrast of the delta O-18 signatures in rainfall (O-18(Pre)) during the dry (O-18-enriched rain) and rainy (O-18-depleted rain) seasons. This difference in O-18(Pre) signal reflects the combination of two signals in the annual tree-ring delta O-18 record. Highly resolved intra-annual 8180 isotope analyses suggest that the signals of dry and rainy season can be distinguished clearly. Thereby reconstructions can improve our understanding of variations and trends of the hydrological cycle over the Indonesian archipelago.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

Oxygen and carbon stable isotopes

Tree rings

Tropics

Dendroclimatology

Monsoon

Multiparameter approach

Tectona grandis

Seasonal rainfall variability

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