Seasonality of precipitation recorded in a modern (1907–2008) annually laminated stalagmite from central China

Seasonality of precipitation in the Asian monsoon region has significant impacts on social and economic development. Here, we analyzed a seasonally resolved δ¹⁸O series of an annually laminated stalagmite from Xianglong Cave to assess its potential as a proxy for seasonal precipitation. The δ¹⁸O values reveal fabric-correlated annual cycles, with lower δ¹⁸O values occurring in the white porous layer (WPL) during summer monsoon (SM) season, whereas higher values occurring in the dark compacted layer (DCL) during non-summer monsoon (NSM) season. We calculated the seasonal amplitude of δ¹⁸O (∆¹⁸O) using the highest value minus the lowest value in an annual cycle. Comparisons suggest that the ∆¹⁸O series can record precipitation seasonality, with lower ∆¹⁸O values corresponding to increased SM/NSM rainfall ratios and higher values corresponding to reduced SM/NSM rainfall ratios. Our reconstruction suggests increased precipitation seasonality contrast (i.e., increasing SM/NSM rainfall ratio with more SM rainfall and/or less NSM rainfall) during 1914–1919, 1935–1942, 1958–1962, 1979–1985, and 1999–2005 (A.D.), with a probably 27-year cycle. The seasonality of precipitation in central China correlates well with the Pacific Decadal Oscillation (PDO) on a decadal scale. Increased SM/NSM rainfall ratio was observed during the warm phase of PDO, and decreased SM/NSM rainfall ratio was observed during the cold phase of PDO.