案例分享 | 使用TDLAS的开路水汽分析仪测量蒸散发通量

本实验成果发布于EGU General Assembly 2023

The relevant paper was published in EGU General Assembly 2023

HT1800水汽开路分析仪Open-path Hygrometer

• 引言

水汽通量对于干旱监测和灌溉管理至关重要。它也是环境评估和生态系统建模的关键参数。

我们之前介绍了一种基于可调谐二极管激光器（TDLAS）的开路水汽分析仪（HT1800，宁波海尔欣光电科技有限公司），适用于涡动相关（EC）法测量水汽通量。

考虑到EC测量的光谱效应校正，我们准备了两台HT1800水汽分析仪进行现场实验。其中一台配备了近1392纳米的红外激光器，另一台配备了近1877纳米的激光器。

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.

• 激光源和吸收线选择

激光源采用垂直腔面发射激光器（VCSEL），为一种功耗低、性价比高的光源。

1392纳米吸收线：TDLAS技术用于水汽检测中最常用的波长之一。

1877纳米吸收线：仿真和实验结果均发现其吸收线形变化较小，与温度的依赖关系较弱。

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

• 现场部署

地点：中国苏州市农业科学院（31°27'09.205''N，120°25'33.222‘’E）

时期1（图a）：

时间：2022年5月7日至16日

风速仪：METEK© u-Sonic3 Cage MP

分析仪1：HT1800（1877纳米）

分析仪2：LI-COR© LI-7500RS

时期2（图b）：

时间：2022年9月10日至10月5日

风速仪：Campbell© CSAT-3

分析仪1：HT1800（1392纳米）

分析仪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

• 结论

我们通过现场部署调查了HT1800在测量水汽通量方面的性能。与另外两台商用分析仪的比较结果表明高度一致性。

采用1392纳米激光源的分析仪由于温度漂移而需要更高的光谱学校正率。然而，经校正后的数据与成熟分析仪的测量结果高度一致。

考虑到其便捷性，本研究证明了基于可调谐二极管激光器的1392纳米激光分析仪可以作为一种经济实惠的解决方案，用于精确测量水汽通量。

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.

• 参考文献：

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.