δ¹⁸O of Marine‐Influenced Tectona grandis L. f. From Equatorial Indonesia: A Local Rainfall Amount and Remote ENSO Indicator

The hydroclimatic response of the El Niño‐Southern Oscillation (ENSO) to external radiative forcing remains controversial and difficult to project with confidence for the 21st century. Annually resolved paleoclimatic reconstructions spanning the pre‐ and post‐industrial eras from the Indonesian maritime continent may provide hindcasting and diagnostic targets. Here we report δ 18 O observations from dendrochronologically dated teak ( Tectona grandis L . f .) α ‐cellulose samples collected at Muna Island, Sulawesi (5.3°S, 123°E, elevation 10 m), for November‐April growing seasons during the period 1969/70–2004/5. Age‐modeled, annually averaged α ‐cellulose δ 18 O anomalies are significantly correlated with simulated α ‐cellulose δ 18 O at the study site. We show that the correlation is largely explained by the amount effect in local and regional precipitation δ 18 O. Significant correlation with SST anomalies over the study period suggest that replicated multicentury α ‐cellulose records from this archive may be interpreted as ENSO indicators.