Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer
The reliable observation and accurate estimates of land–atmosphere water vapor (H<sub>2</sub>O) flux is essential for ecosystem management and the development of Earth system models. Currently, the most direct measurement method for H<sub>2</sub>O flux is eddy covariance (EC)...
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| Format: | Article |
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MDPI AG
2024-01-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/16/2/307 |
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| author | Kai Wang Li Huang Jingting Zhang Xiaojie Zhen Linlin Shi Ting-Jung Lin Xunhua Zheng Yin Wang |
| author_facet | Kai Wang Li Huang Jingting Zhang Xiaojie Zhen Linlin Shi Ting-Jung Lin Xunhua Zheng Yin Wang |
| author_sort | Kai Wang |
| collection | DOAJ |
| description | The reliable observation and accurate estimates of land–atmosphere water vapor (H<sub>2</sub>O) flux is essential for ecosystem management and the development of Earth system models. Currently, the most direct measurement method for H<sub>2</sub>O flux is eddy covariance (EC), which depends on the development of fast-response H<sub>2</sub>O sensors. In this study, we presented a cost-efficient open-path H<sub>2</sub>O analyzer (model: HT1800) based on the tunable diode laser absorption spectroscopy (TDLAS) technique, and investigated its applicability for measuring atmospheric turbulent flux of H<sub>2</sub>O using the EC method. We prepared two HT1800 analyzers with lasers that operate at wavelengths of 1392 nm and 1877 nm, respectively. The field performance of the two analyzers was evaluated through inter-comparative experiments with LI-7500RS and IRGASON, two of the most commonly used H<sub>2</sub>O analyzers in the EC community. Water vapor densities measured by the three types of analyzers had high overall agreement with the reference sensor; however, they all experienced drift. The mean density drifts of HT1800, LI-7500 and IRGASON were 3.7–5.2%, 4.0% and 3.8%, respectively. Even so, the half-hourly H<sub>2</sub>O fluxes measured by HT1800 were highly consistent with those by LI-7500RS and IRGASON (with a difference of less than 2%), suggesting that HT1800 can obtain H<sub>2</sub>O fluxes with high confidence. The HT1800 was also proved to be suitable for EC application in terms of data availability, flux detection limit and response to the high-frequency turbulent variation. Furthermore, we investigated how the spectroscopic effect influences the measurements of H<sub>2</sub>O density and flux. Despite the fact that the 1392 nm laser was much more susceptible to the spectroscopic effect, the fluxes after correcting for this bias showed excellent agreement with the IRGASON fluxes. Considering the cost advantage in laser and photodetector, the HT1800 analyzer using a 1392 nm infrared laser is a promising and economical solution for EC measurement studies of water vapor. |
| first_indexed | 2024-03-08T10:32:24Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-08T10:32:24Z |
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| series | Water |
| spelling | doaj.art-51a9ee56aaa74ba5b72ee9e02fe2c5e22024-01-26T18:51:55ZengMDPI AGWater2073-44412024-01-0116230710.3390/w16020307Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas AnalyzerKai Wang0Li Huang1Jingting Zhang2Xiaojie Zhen3Linlin Shi4Ting-Jung Lin5Xunhua Zheng6Yin Wang7State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaDepartment of Electrical and Electronic Engineering (EEE), University of Nottingham Ningbo China, Ningbo 315100, ChinaDepartment of Electrical and Electronic Engineering (EEE), University of Nottingham Ningbo China, Ningbo 315100, ChinaJiangsu Tynoo Corporation, Wuxi 214135, ChinaInstitute of Agricultural Sciences in Taihu Lake Region of Jiangsu, Suzhou Academy of Agricultural Sciences, Suzhou 215105, ChinaDepartment of Electrical and Electronic Engineering (EEE), University of Nottingham Ningbo China, Ningbo 315100, ChinaState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaHealthyPhoton Technology Co., Ltd., Ningbo 315042, ChinaThe reliable observation and accurate estimates of land–atmosphere water vapor (H<sub>2</sub>O) flux is essential for ecosystem management and the development of Earth system models. Currently, the most direct measurement method for H<sub>2</sub>O flux is eddy covariance (EC), which depends on the development of fast-response H<sub>2</sub>O sensors. In this study, we presented a cost-efficient open-path H<sub>2</sub>O analyzer (model: HT1800) based on the tunable diode laser absorption spectroscopy (TDLAS) technique, and investigated its applicability for measuring atmospheric turbulent flux of H<sub>2</sub>O using the EC method. We prepared two HT1800 analyzers with lasers that operate at wavelengths of 1392 nm and 1877 nm, respectively. The field performance of the two analyzers was evaluated through inter-comparative experiments with LI-7500RS and IRGASON, two of the most commonly used H<sub>2</sub>O analyzers in the EC community. Water vapor densities measured by the three types of analyzers had high overall agreement with the reference sensor; however, they all experienced drift. The mean density drifts of HT1800, LI-7500 and IRGASON were 3.7–5.2%, 4.0% and 3.8%, respectively. Even so, the half-hourly H<sub>2</sub>O fluxes measured by HT1800 were highly consistent with those by LI-7500RS and IRGASON (with a difference of less than 2%), suggesting that HT1800 can obtain H<sub>2</sub>O fluxes with high confidence. The HT1800 was also proved to be suitable for EC application in terms of data availability, flux detection limit and response to the high-frequency turbulent variation. Furthermore, we investigated how the spectroscopic effect influences the measurements of H<sub>2</sub>O density and flux. Despite the fact that the 1392 nm laser was much more susceptible to the spectroscopic effect, the fluxes after correcting for this bias showed excellent agreement with the IRGASON fluxes. Considering the cost advantage in laser and photodetector, the HT1800 analyzer using a 1392 nm infrared laser is a promising and economical solution for EC measurement studies of water vapor.https://www.mdpi.com/2073-4441/16/2/307water vaporfluxopen-path analyzerTDLASeddy covariance |
| spellingShingle | Kai Wang Li Huang Jingting Zhang Xiaojie Zhen Linlin Shi Ting-Jung Lin Xunhua Zheng Yin Wang Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer Water water vapor flux open-path analyzer TDLAS eddy covariance |
| title | Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer |
| title_full | Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer |
| title_fullStr | Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer |
| title_full_unstemmed | Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer |
| title_short | Measuring Turbulent Water Vapor Fluxes Using a Tunable Diode Laser-Based Open-Path Gas Analyzer |
| title_sort | measuring turbulent water vapor fluxes using a tunable diode laser based open path gas analyzer |
| topic | water vapor flux open-path analyzer TDLAS eddy covariance |
| url | https://www.mdpi.com/2073-4441/16/2/307 |
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