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

Abstract

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.