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

Abstract

Long‐term records of precipitation in Thailand are necessary to evaluate the robustness of the relationship between El Niño–Southern Oscillation (ENSO) and rainfall. This study presents a tree ring‐cellulose oxygen isotope (δ18O) record, based on Pinus merkusii, for the period 1804–1999 in Thailand. Response and spatial correlation analyses reveal that tree ring δ18O is significantly correlated with regional monsoon season (May–October) precipitation. Tree ring δ18O, 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.

Increased Variability of Thailand's Chao Phraya River Peak Season Flow and Its Association With ENSO Variability: Evidence From Tree Ring δ18O

“…All five tree ring δ 18 O time series were normalized based on the common period of 1868–1995 and were then averaged to produce the PKK δ 18 O index (Figure S1c). The first order autocorrelation for PKK δ 18 O is 0.20, which is similar with the two other Pinus merkusii δ 18 O indices used for this study: from MHS (0.17, Xu et al, ) and UP (0.16, Xu, Pumijumnong, et al, ). The low autocorrelation for all three δ 18 O records indicates that physiological processes from prior years are not significantly correlated with δ 18 O values in any given year, something that is often strongly expressed for ring width time series (Fritts, 1976).…”

“…The observed CPRPF is positively correlated over the entire CPR basin (Figure S4), which suggests a regional‐scale response to ENSO that is consistent with previous studies (D'Arrigo et al, ; Liu et al, ; Xu et al, ; Xu, Shi, et al, ; Xu, Zheng, et al, ). Specifically, Xu, Pumijumnong, et al () showed that ENSO affects the rainy season precipitation in the central part of the CPR basin and suggested that the reduction in the ENSO‐precipitation relationship between 1930 and 1970 corresponds to the reduced ENSO variance. We computed the spatial correlation map between the observed CPRPF and May–December SST, and the result in Figure a outlines a warm‐phase ENSO (El Niño) with warmer water over the central‐eastern Pacific and the northern Indian Ocean.…”

“…For this study we developed a regional Pinus merkusii δ 18 O index for the CPRB based on the average of three tree ring δ 18 O time series in northern and central Thailand, and northcentral Laos (MHS, UP, and PKK, respectively, as shown in Figure 1a). The PKK δ 18 O time series from Laos is presented for the first time here, along with two previously published records from Thailand (δ 18 O in UP from Xu, Pumijumnong, et al, 2018, andδ 18 O in MHS from Xu et al, 2015).…”

“…Recent studies of δ 18 O from the cellulose of Southeast Asian tree species have demonstrated a connection to regional hydroclimate variability with unprecedented clarity (Sano et al, ; Xu, Pumijumnong, et al, ; Xu et al, ; Xu et al, ; Xu, Sano, et al, ; Zhu, Stott, Buckley, & Yoshimura, ; Zhu, Stott, Buckley, Yoshimura, & Ra, ). These studies all showed that tree ring δ 18 O is significantly correlated with monsoon season precipitation (Xu et al, ; Xu, Sano, et al, ; Zhu, Stott, Buckley, & Yoshimura, ; Zhu, Stott, Buckley, Yoshimura, & Ra, ).…”

A 177 Years Extended of Teak Chronology Revealing to the Climate Variability in Phrae Province, Northern of Thailand

“…In addition, remarkably, the reconstructed rainfall also showed a similar trend with the annual rainy season rainfall (1804-1999) reconstructed by tree ring oxygen isotopes, which was aligned well with actual amount of rainfall, although it derived from Pinus merkusii in Tak Province, western Thailand [56]. The pattern between our reconstructed rainfall in Phrae and reconstructed rainfall in Tak from Xu et al [56] was noticeably similar, particularly in rainy season during 1935-1945, dry season during 1915 and 1925 and after 1990. Since the Phrae chronology in this study matches fairly well with other previous studies, it seems that the northern Thailand climate was influenced by monsoon signal with effects on both local and regional scales.…”