Inter-annual and multi-decadal variability of monsoon season rainfall in central Thailand during the period 1804-1999, as inferred from tree ring oxygen isotopes

摘要

Long-term records of precipitation in Thailand are necessary to evaluate the robustness of the relationship between El Nino-Southern Oscillation (ENSO) and rainfall. This study presents a tree ring-cellulose oxygen isotope (delta O-18) record, based on Pinus merkusii, for the period 1804-1999 in Thailand. Response and spatial correlation analyses reveal that tree ring delta O-18 is significantly correlated with regional monsoon season (May-October) precipitation. Tree ring delta O-18, which explains 50.1% of the variability in regional precipitation, was employed to reconstruct monsoon season rainfall back to 1804. Relatively wet periods occurred in 1809-1821, 1876-1882, 1897-1908, and 1944-1975, while the periods 1825-1850, 1913-1925, and 1979-1997 were relatively dry. During the periods 1854-1930 and 1970-1999, inter-annual variability of precipitation was modulated by the ENSO. In contrast, the absence of this relationship between 1930 and 1970 might relate to the reduced variance of ENSO.