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Title: Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent
Authors: He, Shaoneng
Jackisc, Dominik
Samanta, Dhrubajyoti
Kho, Phyllis Yu Yi
Liu, Guangxin
Wang, Xianfeng
Goodkin, Nathalie Fairbank
Keywords: Social sciences::Geography::Environmental sciences
Issue Date: 2021
Source: He, S., Jackisc, D., Samanta, D., Kho, P. Y. Y., Liu, G., Wang, X. & Goodkin, N. F. (2021). Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent. Journal of Geophysical Research: Atmospheres, 126(4), e2020JD033418-.
Project: NRF2017NRF-NSFC001-047 
CRP Code: F31004 
Journal: Journal of Geophysical Research: Atmospheres 
Abstract: Monthly precipitation samples from Singapore were collected between 2013 and 2019 for stable isotope analysis to further our understanding of the drivers of tropical precipitation isotopes, in particular, 17O-excess. d18O ranges from -11.34‰ to -2.34‰, with a low correlation to rainfall (r=-0.31, p=0.014), suggesting a weak amount effect. d-excess is relatively consistent and has an average value of 10.89±3.45‰. Compared to high-latitude regions, 17O-excess in our samples generally falls in a narrower range from 2 to 47 per meg with an average of 21±11 per meg. Moreover, 17O-excess shows strong periodic variability; spectral analysis reveals 3-month, 6-month and 2.7-year periodicities, likely corresponding to intra-seasonal oscillations, monsoons and the El Niño–Southern Oscillation (ENSO), respectively. In contrast, d-excess shows no clear periodicities. Although spectral analysis only identifies 6-month periodicity in the d18O time series, d18O tracks the Nino3.4 sea surface temperature variability; the average d18O value (-5.2‰) is higher during El Niño years than ENSO neutral years (-7.6‰). Therefore, regional convection associated with monsoons and ENSO has different impacts on d18O, d-excess and 17O-excess. 17O-excess and d-excess are anti-correlated, and do not relate to the relative humidity in moisture source regions. Extremely low humidity and drought conditions in moisture source regions would be required to account for high 17O-excess. Processes during transport and precipitation likely modify these two parameters, especially 17O-excess, which no longer record humidity conditions of moisture source regions. Our findings will be useful for further modeling studies to identify physical processes during convection that alter d-excess and 17O-excess.
ISSN: 2169-897X
DOI: 10.1029/2020JD033418
Rights: © 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Fulltext Permission: open
Fulltext Availability: With Fulltext
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