第八届青年地学论坛

As the Earth’s atmosphere warms, the climate changes dynamically and thermodynamically, which inevitably influences East Asian summer monsoon (EASM) and the oxygen isotope (δ¹⁸O) compositions of its precipitations. Here, we provide for the first time a precisely dated (±3 yrs, 2s) and high-resolution speleothemδ¹⁸O record from Shandong Peninsula, eastern China. We further extracted the first principal component (PC1) and monte carlo empirical orthogonal function (MCEOF1) among six high-resolution (≤1 year) speleothem records in EASM domains. They indicated a long-term weakening trend of EASM within the Global Warming (GW) period, which are virtually consistent and coherent with the GW trend with two slowdowns and two accelerations. Diagnostic results using CERA-20C dataset revealed the anomalous moistures flux patterns in Asian summer monsoon (ASM) domains, with one anticyclone and two cyclones of moistures flux, which significantly weakened the synthesized southerly moistures in East Asia. The ‘sandwich pattern’ of spatial heterogeneity of GW in ASM domains, which is controlled by both greenhouse gas and aerosols, nicely integrates the anomalous moistures flux patterns and provides to link between the GW and speleothem δ¹⁸O.This observation also suggests that the coherent variation of the speleothem δ¹⁸O records in EASM region over the last century is a manifestation of large-scale dynamical changes of the summer monsoon circulation in tropics-subtropics.

 

Speleothem δ18O, monsoon weakening, GW, CERA-20C