Open-path cell for online measurement of atmospheric H2O and CO2 fluxes

Tế bào nhiều đường dẫn mở giúp đo trực tuyến các thông lượng H2O và CO2 trong khí quyển

Photograph of the TDLAS sensor and diagram of the open-path TDLAS system used to measure H in the atmosphere2O and CO2 concentration. Credit: Gu Mingsi

According to a study published in fast opticsA research team from the Hefei Institute of Physical Sciences of the Chinese Academy of Sciences has proposed a new design for online measurement of atmospheric H.2O and CO2 flux.

“We designed an open and pollution-resistant multipath cell, and applied it on a tunable diode laser absorption spectrophotometer sensor,” said Professor Gao Xiaoming, who led the research team. correction (TDLAS)”.

The new gas analyzer exhibits good consistency with commercial instruments and its accuracy is comparable.

One of the most important ways to reduce greenhouse gas concentration is to store carbon in soil and vegetation. Scientists propose to use turbulent vortices created by airflow to measure greenhouse gas emissions.

  • Open-path cell for online measurement of atmospheric H2O and CO2 fluxes

    Installation snapshot and comparison of field measurements obtained using TDLAS and LI-7500 over 24 hours. Credit: Gu Mingsi

  • Open-path cell for online measurement of atmospheric H2O and CO2 fluxes

    Compare (a) CO2 flux and (b) H2O flux for about a month. Credit: Gu Mingsi

The instrument based on tunable laser absorption spectroscopy combined with vortex covariance technology has many advantages including high sensitivity, high precision and fast response. There are two airway methods for measuring air flow: open path and closed path. However, the traditional open multipath cell is not suitable because its optical path is exposed to the air, causing the coating of the lens to corrode in the atmosphere.

Different from the traditional multi-path cells, this new anti-pollution open multi-path cell mainly consists of two planar-convex mirrors coated on a convex surface.

“It’s covered on the back,” Gao said. “The design does not allow direct contact between the lens coating and the air, which is why it is anti-pollution.”

This design effectively avoids contamination and corrosion of the lens film by the external environment. When it is applied to atmospheric CO flux monitoring equipment2 and THEY2O, the long-term stability and durability of the open path system are improved.

Open-path cell for online measurement of atmospheric H2O and CO2 fluxes

The researchers set up a homemade instrument for a comparative observational experiment. Credit: by Gu Mingsi

The design was further demonstrated in a field comparative observation experiment on CO .2 and THEY2O flux of the cropland ecosystem according to the wheat season. The results are in good agreement with those obtained using commercial equipment based on non-dispersive infrared.

“We see strong application prospects for flush measurements in any ecosystem,” said Gao.

More information:
Mingsi Gu et al., Open-path anti-pollution multidimensional cell-based TDLAS sensor for on-line measurement of atmospheric H2O and CO2 fluxes, fast optics (2022). DOI: 10.1364/OE.474070

quote: Open-path cell for online measurements of atmospheric H2O and CO2 fluxes (2022, December 7) retrieved December 8, 2022 from -open-path-multi-pass-cell -atmosphere-h2o.html

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