Continuous real‐time analysis of the isotopic composition of precipitation during tropical rain events: Insights into tropical convection

作者：Shaoneng He, Nathalie F. Goodkin, Dominik Jackisch, Maria Rosabelle Ong, Dhrubajyoti Samanta · 发表于：Hydrological Processes · 年份：2018 · DOI：10.1002/hyp.11520 · 被引用次数：40 · 研究领域：Climate variability and models、Geology and Paleoclimatology Research、Groundwater and Isotope Geochemistry

Abstract To investigate stable isotopic variability of precipitation in Singapore, we continuously analysed the δ‐value of individual rain events from November 2014 to August 2017 using an online system composed of a diffusion sampler coupled to Cavity Ring‐Down Spectrometer. Over this period, the average value (δ 18 O Avg ), the lowest value (δ 18 O Low ), and the initial value (δ 18 O Init ) varied significantly, ranging from −0.45 to −15.54‰, −0.9 to −17.65‰, and 0 to −13.13‰, respectively. All 3 values share similar variability, and events with low δ 18 O Low and δ 18 O Avg values have low δ 18 O Init value. Individual events have limited intraevent variability in δ‐value (Δδ) with the majority having a Δδ below 4‰. Correlation of δ 18 O Low and δ 18 O Avg with δ 18 O Init is much higher than that with Δδ, suggesting that convective activities prior to events have more control over δ‐value than on‐site convective activities. The d‐excess of events also varies considerably in response to the seasonal variation in moisture sources. A 2‐month running mean analysis of δ 18 O reveals clear seasonal and interannual variability. Seasonal variability is associated with the meridional movement of the Intertropical Convergence Zone and evolution of the Asian monsoon. El Niño–Southern Oscillation is a likely driver of interannual variability. During 2015–2016, the strongest El Niño year in recorded history, the majority of events have a δ 18 O value higher than the weighted average ...