Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes

Due to limited water vapor measurements, vapor isotopes have been traditionally estimated under the assumption of isotopic equilibrium between rain and vapor below cloud base. However, recent advancements in analytical instruments allow more vapor isotopic measurements that have challenged this assu...

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Main Authors: He, Shaoneng, Jackisch, Dominik, Feng, Lujia, Samanta, Dhrubajyoti, Wang, Xianfeng, Goodkin, Nathalie F.
Other Authors: Asian School of the Environment
Format: Article
Language:English
Published: 2025
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Online Access:https://hdl.handle.net/10356/182099
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1820992025-01-13T15:30:49Z Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes He, Shaoneng Jackisch, Dominik Feng, Lujia Samanta, Dhrubajyoti Wang, Xianfeng Goodkin, Nathalie F. Asian School of the Environment Earth Observatory of Singapore Earth and Environmental Sciences Below-cloud processes Rain evaporation Due to limited water vapor measurements, vapor isotopes have been traditionally estimated under the assumption of isotopic equilibrium between rain and vapor below cloud base. However, recent advancements in analytical instruments allow more vapor isotopic measurements that have challenged this assumption. To enhance our understanding of rain-vapor interactions below cloud base in tropical regions, we established an automated system to measure rain and vapor isotopes simultaneously and continuously in real time at minute intervals in Singapore. Among 324 rain events monitored from 2016 to 2019, 81% exhibited a substantial departure of rain and vapor isotopes from the expected equilibrium. This departure suggests that raindrop evaporation plays a larger role in determining their isotopes. The conclusion is supported by the generally lower slopes of the local meteoric water line. Seasonal variations in rain event characteristics indicate changing influences of rain-vapor interactions: during monsoons, more frequent heavy rainfall maintains relatively high humidity below cloud base, favoring rain-vapor isotopic equilibrium, whereas during inter-monsoons, more light rain events lead to pronounced rain evaporation and larger isotopic differences. Furthermore, rain-vapor interactions below cloud base significantly modulated their isotope evolution during individual events. As events progressed, reduced humidity favored evaporation, increasing rain isotope values and decreasing its d-excess, whereas vapor isotope values decreased and its d-excess increased. Our study introduces a new approach to capturing real-time high-resolution rain and vapor isotopes at minute intervals to understand the dynamics of rain-vapor interactions below cloud base. Findings underscore the crucial role of these interactions in influencing rain and vapor isotopes during tropical rain events. Ministry of Education (MOE) National Research Foundation (NRF) Published version The authors gratefully acknowledge the financial support provided by the Singapore Ministry of Education (Grant MOE‐MOET2EP10121‐0008). This research is also supported by the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative. 2025-01-07T08:01:12Z 2025-01-07T08:01:12Z 2024 Journal Article He, S., Jackisch, D., Feng, L., Samanta, D., Wang, X. & Goodkin, N. F. (2024). Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes. Journal of Geophysical Research: Atmospheres, 129(22). https://dx.doi.org/10.1029/2023JD040084 2169-897X https://hdl.handle.net/10356/182099 10.1029/2023JD040084 2-s2.0-85208957939 22 129 en MOE‐MOET2EP10121‐0008 Journal of Geophysical Research: Atmospheres © 2024 American Geophysical Union. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the copyright holder. The Version of Record is available online at http://doi.org/10.1029/2023JD040084 application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Earth and Environmental Sciences
Below-cloud processes
Rain evaporation
spellingShingle Earth and Environmental Sciences
Below-cloud processes
Rain evaporation
He, Shaoneng
Jackisch, Dominik
Feng, Lujia
Samanta, Dhrubajyoti
Wang, Xianfeng
Goodkin, Nathalie F.
Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes
description Due to limited water vapor measurements, vapor isotopes have been traditionally estimated under the assumption of isotopic equilibrium between rain and vapor below cloud base. However, recent advancements in analytical instruments allow more vapor isotopic measurements that have challenged this assumption. To enhance our understanding of rain-vapor interactions below cloud base in tropical regions, we established an automated system to measure rain and vapor isotopes simultaneously and continuously in real time at minute intervals in Singapore. Among 324 rain events monitored from 2016 to 2019, 81% exhibited a substantial departure of rain and vapor isotopes from the expected equilibrium. This departure suggests that raindrop evaporation plays a larger role in determining their isotopes. The conclusion is supported by the generally lower slopes of the local meteoric water line. Seasonal variations in rain event characteristics indicate changing influences of rain-vapor interactions: during monsoons, more frequent heavy rainfall maintains relatively high humidity below cloud base, favoring rain-vapor isotopic equilibrium, whereas during inter-monsoons, more light rain events lead to pronounced rain evaporation and larger isotopic differences. Furthermore, rain-vapor interactions below cloud base significantly modulated their isotope evolution during individual events. As events progressed, reduced humidity favored evaporation, increasing rain isotope values and decreasing its d-excess, whereas vapor isotope values decreased and its d-excess increased. Our study introduces a new approach to capturing real-time high-resolution rain and vapor isotopes at minute intervals to understand the dynamics of rain-vapor interactions below cloud base. Findings underscore the crucial role of these interactions in influencing rain and vapor isotopes during tropical rain events.
author2 Asian School of the Environment
author_facet Asian School of the Environment
He, Shaoneng
Jackisch, Dominik
Feng, Lujia
Samanta, Dhrubajyoti
Wang, Xianfeng
Goodkin, Nathalie F.
format Article
author He, Shaoneng
Jackisch, Dominik
Feng, Lujia
Samanta, Dhrubajyoti
Wang, Xianfeng
Goodkin, Nathalie F.
author_sort He, Shaoneng
title Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes
title_short Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes
title_full Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes
title_fullStr Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes
title_full_unstemmed Uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes
title_sort uncovering below cloud rain‐vapor interactions during tropical rain events through simultaneous and continuous real‐time monitoring of rain and vapor isotopes
publishDate 2025
url https://hdl.handle.net/10356/182099
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