Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent

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=...

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Main Authors: He, Shaoneng, Jackisc, Dominik, Samanta, Dhrubajyoti, Kho, Phyllis Yu Yi, Liu, Guangxin, Wang, Xianfeng, Goodkin, Nathalie Fairbank
Other Authors: Asian School of the Environment
Format: Article
Language:English
Published: 2021
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Online Access:https://hdl.handle.net/10356/149075
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spelling sg-ntu-dr.10356-1490752021-05-29T20:11:03Z Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent He, Shaoneng Jackisc, Dominik Samanta, Dhrubajyoti Kho, Phyllis Yu Yi Liu, Guangxin Wang, Xianfeng Goodkin, Nathalie Fairbank Asian School of the Environment Earth Observatory of Singapore Social sciences::Geography::Environmental sciences Monthly Precipitation Moisture Source Humidity Stable Isotopes 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. Ministry of Education (MOE) National Research Foundation (NRF) Published version This research is supported by the National Research Foundation Singapore and the Singapore Ministry of Educa-tion under the Research Centres of Excellence initiative. It comprises Earth Observatory of Singapore contribution no. 273. The partial financial support is provided by the NRF-NSFC joint grant (NRF2017NRF-NSFC001-047 to X.W.). This research is also the part of IAEA Coordinated Research Project (CRP Code: F31004) on “Stable isotopes in precipitation and paleoclimatic archives in tropical areas to improve regional hydrological and climatic impact model” with IAEA Research Agreement No. 17980. 2021-05-25T01:03:28Z 2021-05-25T01:03:28Z 2021 Journal Article 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-. https://dx.doi.org/10.1029/2020JD033418 2169-897X https://hdl.handle.net/10356/149075 10.1029/2020JD033418 4 126 e2020JD033418 en NRF2017NRF-NSFC001-047 CRP Code: F31004 Journal of Geophysical Research: Atmospheres © 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. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Social sciences::Geography::Environmental sciences
Monthly Precipitation
Moisture Source Humidity
Stable Isotopes
spellingShingle Social sciences::Geography::Environmental sciences
Monthly Precipitation
Moisture Source Humidity
Stable Isotopes
He, Shaoneng
Jackisc, Dominik
Samanta, Dhrubajyoti
Kho, Phyllis Yu Yi
Liu, Guangxin
Wang, Xianfeng
Goodkin, Nathalie Fairbank
Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent
description 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.
author2 Asian School of the Environment
author_facet Asian School of the Environment
He, Shaoneng
Jackisc, Dominik
Samanta, Dhrubajyoti
Kho, Phyllis Yu Yi
Liu, Guangxin
Wang, Xianfeng
Goodkin, Nathalie Fairbank
format Article
author He, Shaoneng
Jackisc, Dominik
Samanta, Dhrubajyoti
Kho, Phyllis Yu Yi
Liu, Guangxin
Wang, Xianfeng
Goodkin, Nathalie Fairbank
author_sort He, Shaoneng
title Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent
title_short Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent
title_full Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent
title_fullStr Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent
title_full_unstemmed Understanding tropical convection through triple oxygen isotopes of precipitation from the Maritime Continent
title_sort understanding tropical convection through triple oxygen isotopes of precipitation from the maritime continent
publishDate 2021
url https://hdl.handle.net/10356/149075
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