Abstract
A 338-year oxygen isotope record from teak tree-ring cellulose collected from Mae Hong Son province in northwestern Thailand was presented. The tree-ring series preserves the isotopic signal of the regional wet season rainfall and relative humidity. Tree-ring δ18O correlates strongly with regional rainfall from May to October, showing coherent variations over large areas in Southeast Asia. We reconstructed the summer monsoon season (May to October) rainfall based on a linear regression model that explained 35.2% of the actual rainfall variance. Additionally, we found that in the 19th century, there was a remarkable drought during many years that corresponded to regional historic drought events. The signals of the June to September Indian summer monsoon (ISM) for the period between 1948 and 2009 were clearly found. Spatial correlations and spectral analyses revealed a strong impact of the El Niño-Southern Oscillation (ENSO) on tree-ring δ18O. However, ENSO influenced the tree-ring δ18O more strongly in the 1870–1906, 1907–1943, and 1944–1980 periods than in the 1981–2015 period, which corresponded to periods of weaker and stronger ISM intensity.
Highlights
A 338-year oxygen isotope record from teak tree-ring cellulose collected from Mae Hong Son province in northwestern Thailand was presented
Variations in oxygen isotope series in teak wood are expected to reflect the variations in oxygen isotope ratios in seasonal rainfall, which is affirmed by the significant positive correlation between δ18Otr and annual δ18O in rainfall from the Global Network of Isotopes in Precipitation (GNIP) station in Bangkok (August r = 0.289, p < 0.045, n = 48, October r r = 0.321, p < 0.030, n = 46)
Duy et al.[33] concluded that the variation in oxygen isotopes in rainwater is 70% controlled by regional moisture regimes compared to local climatic conditions (30%), and regional and local factors vary in importance seasonally and have a large influence on the isotopic composition of rainfall
Summary
A 338-year oxygen isotope record from teak tree-ring cellulose collected from Mae Hong Son province in northwestern Thailand was presented. We produced the longest oxygen isotope chronology currently available from tree-ring cellulose of teak and examined the influence of local and regional climate parameters on oxygen isotope ratios (δ18O) to improve our understanding of ASM variability during the past 338 years.
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