Typhoon Control of Precipitation Dual Isotopes in Southern China and Its Palaeoenvironmental Implications
Fajin Chen, Chao Huang, Qibin Lao, Shuwen Zhang, Chunqing Chen, Xin Zhou, Xuan Lü, Qingmei Zhu
Abstract
Abstract High‐resolution stalagmite oxygen isotope (δ 18 O) records are widely employed in palaeoclimate studies as indicators of East Asian Monsoon intensity in southern China. A key issue is whether the East Asian Monsoon or other factors control δ 18 O in precipitation in southern China, which requires modern observations to confirm. To understand which factors control the dual isotopes ( δ D and δ 18 O) of precipitation in southern China, δ D and δ 18 O were measured from 412 precipitation events (including 144 rainwater samples from a total of 43 typhoon events) from May 2015 to April 2020 in Zhanjiang, a tropical city frequently affected by typhoon events in southern China. The overall relationship between δ D and δ 18 O can be expressed as δ D = 8.961 δ 18 O + 6.235; significantly lower intercept and larger slope of this relationship compared to these of the global meteoric water line (GMWL) and the China meteoric water line (CMWL). Remarkably, significantly low D‐excess and the lowest δ D and δ 18 O occurred in the typhoon periods, suggesting that typhoon events could bring large amounts of remote moisture to this tropical city from the Western Pacific and South China Sea. The moisture from remote oceans would affect precipitation with the lowest δ 18 O and D‐excess, which could be responsible for the deviation of the slope and intercept from those of the CMWL and GMWL. Therefore, variations of the δ 18 O in precipitation are intensively influenced by typhoons, not by the East Asian Monsoon, providing new understanding for the interpretation of palaeo‐isotope data in southern China.