One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensity

<p>Atmospheric water vapor stable isotopes are crucial for understanding hydrological cycle processes under climate change. This study presents the results from a year-long in situ monitoring of atmospheric water vapor stable isotopes (<span class="inline-formula"><i>δ<...

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Main Authors: Y. Wu, J. Gao, A. Zhao, X. Niu, Y. Liu, D. Ratnasekera, T. P. Gamage, A. H. R. Samantha
Format: Article
Language:English
Published: Copernicus Publications 2025-04-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/25/4013/2025/acp-25-4013-2025.pdf
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author Y. Wu
Y. Wu
J. Gao
J. Gao
A. Zhao
X. Niu
Y. Liu
Y. Liu
D. Ratnasekera
D. Ratnasekera
T. P. Gamage
A. H. R. Samantha
author_facet Y. Wu
Y. Wu
J. Gao
J. Gao
A. Zhao
X. Niu
Y. Liu
Y. Liu
D. Ratnasekera
D. Ratnasekera
T. P. Gamage
A. H. R. Samantha
author_sort Y. Wu
collection DOAJ
description <p>Atmospheric water vapor stable isotopes are crucial for understanding hydrological cycle processes under climate change. This study presents the results from a year-long in situ monitoring of atmospheric water vapor stable isotopes (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O, <span class="inline-formula"><i>δ</i></span>D) at Matara, Sri Lanka, from March 2020 to February 2021 to assess how oceanic sources and moisture transport influence coastal atmospheric moisture isotopic composition. We identified clear seasonal patterns in the isotopic composition, with <span class="inline-formula"><i>δ</i><sup>18</sup></span>O, <span class="inline-formula"><i>δ</i></span>D, and d-excess showing substantial variation between the southwest and northeast monsoon periods. The primary moisture sources were the Arabian Sea and the Indian Ocean during the southwest monsoon (May to September), characterized by small amplitude fluctuations of <span class="inline-formula"><i>δ</i><sup>18</sup></span>O (<span class="inline-formula">−</span>20.4 ‰ to <span class="inline-formula">−</span>9.1 ‰). During the northeast monsoon, the northern Bay of Bengal, the Indian subcontinent, and Southeast Asia were primary moisture sources, resulting in large-amplitude fluctuations in <span class="inline-formula"><i>δ</i><sup>18</sup></span>O (<span class="inline-formula">−</span>23.9 ‰ to <span class="inline-formula">−</span>7.5 ‰) and higher d-excess values (up to 25 ‰). The study also identified significant influences of sea surface temperature and sea surface relative humidity on the isotopic composition of water vapor. Additionally, we could use outgoing longwave radiation (OLR) to gauge the intensity of convective activity. Observational periods with low OLR, indicative of stronger and deeper convection, were associated with air masses that were more depleted in <span class="inline-formula"><i>δ</i><sup>18</sup></span>O than periods with high OLR. These findings facilitate a better understanding of how the monsoon and local meteorological conditions affect water vapor isotope compositions in tropical regions. Furthermore, the new dataset will enable us to improve water vapor isotopic modeling and projections of atmospheric processes in coastal regions.</p>
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spelling doaj-art-78eb2ebdf8e743e0af96bf52d336caf62025-08-20T03:17:28ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-04-01254013403310.5194/acp-25-4013-2025One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensityY. Wu0Y. Wu1J. Gao2J. Gao3A. Zhao4X. Niu5Y. Liu6Y. Liu7D. Ratnasekera8D. Ratnasekera9T. P. Gamage10A. H. R. Samantha11State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaState Key Laboratory of Tibetan Plateau Earth System, Resources and Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, ChinaLanzhou University, Lanzhou 733000, ChinaState Key Laboratory of Tibetan Plateau Earth System, Resources and Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, ChinaState Key Laboratory of Tibetan Plateau Earth System, Resources and Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, ChinaState Key Laboratory of Tibetan Plateau Earth System, Resources and Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaChina-Sri Lanka Joint Center for Education and Research, Guangzhou 510301, ChinaDepartment of Agricultural Biology, Faculty of Agriculture, University of Ruhuna, Matara 81000, Sri LankaFaculty of Fisheries and Marine Sciences & Technology, University of Ruhuna, Matara 81000, Sri LankaFaculty of Fisheries and Marine Sciences & Technology, University of Ruhuna, Matara 81000, Sri Lanka<p>Atmospheric water vapor stable isotopes are crucial for understanding hydrological cycle processes under climate change. This study presents the results from a year-long in situ monitoring of atmospheric water vapor stable isotopes (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O, <span class="inline-formula"><i>δ</i></span>D) at Matara, Sri Lanka, from March 2020 to February 2021 to assess how oceanic sources and moisture transport influence coastal atmospheric moisture isotopic composition. We identified clear seasonal patterns in the isotopic composition, with <span class="inline-formula"><i>δ</i><sup>18</sup></span>O, <span class="inline-formula"><i>δ</i></span>D, and d-excess showing substantial variation between the southwest and northeast monsoon periods. The primary moisture sources were the Arabian Sea and the Indian Ocean during the southwest monsoon (May to September), characterized by small amplitude fluctuations of <span class="inline-formula"><i>δ</i><sup>18</sup></span>O (<span class="inline-formula">−</span>20.4 ‰ to <span class="inline-formula">−</span>9.1 ‰). During the northeast monsoon, the northern Bay of Bengal, the Indian subcontinent, and Southeast Asia were primary moisture sources, resulting in large-amplitude fluctuations in <span class="inline-formula"><i>δ</i><sup>18</sup></span>O (<span class="inline-formula">−</span>23.9 ‰ to <span class="inline-formula">−</span>7.5 ‰) and higher d-excess values (up to 25 ‰). The study also identified significant influences of sea surface temperature and sea surface relative humidity on the isotopic composition of water vapor. Additionally, we could use outgoing longwave radiation (OLR) to gauge the intensity of convective activity. Observational periods with low OLR, indicative of stronger and deeper convection, were associated with air masses that were more depleted in <span class="inline-formula"><i>δ</i><sup>18</sup></span>O than periods with high OLR. These findings facilitate a better understanding of how the monsoon and local meteorological conditions affect water vapor isotope compositions in tropical regions. Furthermore, the new dataset will enable us to improve water vapor isotopic modeling and projections of atmospheric processes in coastal regions.</p>https://acp.copernicus.org/articles/25/4013/2025/acp-25-4013-2025.pdf
spellingShingle Y. Wu
Y. Wu
J. Gao
J. Gao
A. Zhao
X. Niu
Y. Liu
Y. Liu
D. Ratnasekera
D. Ratnasekera
T. P. Gamage
A. H. R. Samantha
One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensity
Atmospheric Chemistry and Physics
title One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensity
title_full One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensity
title_fullStr One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensity
title_full_unstemmed One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensity
title_short One-year continuous observations of near-surface atmospheric water vapor stable isotopes at Matara, Sri Lanka, reveal a strong link to moisture sources and convective intensity
title_sort one year continuous observations of near surface atmospheric water vapor stable isotopes at matara sri lanka reveal a strong link to moisture sources and convective intensity
url https://acp.copernicus.org/articles/25/4013/2025/acp-25-4013-2025.pdf
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