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使用TDLAS的開路水汽分析儀測量蒸散發(fā)通量
本實(shí)驗(yàn)成果發(fā)布于EGU General Assembly 2023
The relevant paper was published in EGU General Assembly 2023
HT1800水汽開路分析儀
Open-path Hygrometer
Open-path Hygrometer
01實(shí)驗(yàn)背景：
水汽通量對(duì)于干旱監(jiān)測和灌溉管理至關(guān)重要。它也是環(huán)境評(píng)估和生態(tài)系統(tǒng)建模的關(guān)鍵參數(shù)。
我們之前介紹了一種基于可調(diào)諧二極管激光器(TDLAS)的開路水汽分析儀(HT1800，寧波海爾欣光電科技有限公司)，適用于渦動(dòng)相關(guān)(EC)法測量水汽通量。
考慮到EC測量的光譜效應(yīng)校正，我們準(zhǔn)備了兩臺(tái)HT1800水蒸氣分析儀進(jìn)行現(xiàn)場實(shí)驗(yàn)。其中一臺(tái)配備了近1392納米的紅外激光器，另一臺(tái)配備了近1877納米的激光器。
Introduction
Water vapor flux is essential for drought monitoring and irrigation management. It is also a key parameter for environmental assessment and ecosystem modeling.
We have earlier presented a TDLAS-based open-path water vapor analyzer (HT1800, HealthyPhoton Co., Ltd.), which is suitable for eddy covariance (EC) measurement of water vapor flux.
Considering spectroscopic effect correction for EC measurement, we prepared two HT1800 water vapor analyzers for field experiments. One is equipped with an infrared laser operating near 1392 nm, and the other near 1877 nm.
02激光源和吸收線選擇：
激光源采用垂直腔面發(fā)射激光器(VCSEL)，為一種功耗低、性價(jià)比高的光源。
1392納米吸收線：TDLAS技術(shù)用于水汽檢測中常用的波長之一。
1877納米吸收線：仿真和實(shí)驗(yàn)結(jié)果均發(fā)現(xiàn)其吸收線形變化較小，與溫度的依賴關(guān)系較弱。
Laser source and absorption line selection
Vertical cavity surface emitting laser (VCSEL): low-power consumption and cost-effective light source
1392nm: one of the most used for TDLAS detection of water vapor
1877nm: found to have less temperature-dependent absorption lineshape variations
03現(xiàn)場部署：
地點(diǎn)：
中國蘇州市農(nóng)業(yè)科學(xué)院(31°27'09.205''N，120°25'33.222‘’E)
時(shí)期1(圖a)：
• 時(shí)間：2022年5月7日至16日
• 風(fēng)速儀：METEK© u-Sonic3 Cage MP
• 分析儀1：HT1800(1877納米)
• 分析儀2：LI-COR© LI-7500RS
時(shí)期2(圖b)：
• 時(shí)間：2022年9月10日至10月5日
• 風(fēng)速儀：Campbell© CSAT-3
• 分析儀1：HT1800(1392納米)
• 分析儀2：Campbell© EC150
Field deployment
Site:
Suzhou Academy of Agricultural Sciences of China. (31°27'09.205''N, 120°25'33.222‘’E)
Period 1 (figure a):
Time: May 7−16, 2022
Anemometer: METEK© u-Sonic3 Cage MP
Analyzer 1: HT1800 (1877nm)
Analyzer 2: LI-COR© LI-7500RS
Period 2 (figure b):
Time: September 10−October 5, 2022
Anemometer: Campbell© CSAT-3
Analyzer 1: HT1800 (1392nm)
Analyzer 2: Campbell© EC150
結(jié)論
我們通過現(xiàn)場部署調(diào)查了HT1800在測量水蒸氣通量方面的性能。與另外兩臺(tái)商用分析儀的比較結(jié)果表明高度一致性。
采用1392納米激光源的分析儀由于溫度漂移而需要更高的光譜學(xué)校正率。然而，經(jīng)校正后的數(shù)據(jù)與成熟分析儀的測量結(jié)果高度一致。
考慮到其便捷性，本研究證明了基于可調(diào)諧二極管激光器的1392納米激光分析儀可以作為一種經(jīng)濟(jì)實(shí)惠的解決方案，用于精確測量水蒸氣通量。
Conclusions
We investigated the HT1800 performance of measuring water vapor flux through field deployment. The comparisons with another two commercial analyzers showed high consistency.
The analyzer with a 1392nm laser source leads to a higher spectroscopic correction rate due to temperature drift. However, the corrected data showed a high degree of agreement with the measurements from a mature analyzer.
Considering its convenient availability, this work demonstrated that a TDLAS-based analyzer with a 1392nm laser could be used as a cost-effective solution to measure water vapor flux precisely.
參考文獻(xiàn)：
Ting-Jung Lin, Kai Wang, Yin Wang, Zhimei Liu, Xiaojie Zhen, Xiaohua Zhang, Li Huang, Jingting Zhang, and Xunhua Zheng, “Measuring evapotranspiration fluxes using a tunable diode laser-based open-path water vapor analyzer”, EGU General Assembly 2023, EGU23-4030, 2023.