Atmospheric CO2 measurement using dispersive Infrared Spectroscopy with a scanning Fabry-Perot Interferometer Sensor
Research output: Chapters, Conference Papers, Creative and Literary Works › RGC 32 - Refereed conference paper (with host publication) › peer-review
Author(s)
Related Research Unit(s)
Detail(s)
Original language | English |
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Title of host publication | EGU General Assembly 2014 |
Place of Publication | Munich |
Publisher | European Geosciences Union |
Publication status | Published - Apr 2014 |
Publication series
Name | Geophysical Research Abstracts (GRA) |
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Volume | 16 |
ISSN (electronic) | 1607-7962 |
Conference
Title | European Geosciences Union General Assembly 2014 |
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Place | Australia |
City | Vienna |
Period | 27 April - 2 May 2014 |
Link(s)
Document Link | Links
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Permanent Link | https://scholars.cityu.edu.hk/en/publications/publication(47d2b8e8-4e47-4065-a989-252c317f9d1d).html |
Abstract
A novel infrared absorption spectroscopic based measurement technique was developed for atmospheric CO2 measurement by using a new scanning Febry-Pérot interferometer sensor. The sensor measures the optical spectra in the mid infrared (3900nm to 5220nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO2 absorption band (∼4280 nm) and sampling resolution of 20 nm. The CO2 concentration is determined from the measured optical absorption spectra by fitting it to the CO2 reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H2O), was taken out by including their reference spectra in the fit as well. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented.
A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO2 measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO2 measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO2 analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. A CO2 episode observed during the measurement period was analysis by the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Result shows the air mass was recirculated in the region which indicates that the CO2 episode may result from the accumulation of local emissions. A pronounced bimodal CO2 diurnal profile was observed indicating the CO2 concentration is mainly related to the increase in traffic load during the rush hours.
A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO2 measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO2 measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO2 analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. A CO2 episode observed during the measurement period was analysis by the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Result shows the air mass was recirculated in the region which indicates that the CO2 episode may result from the accumulation of local emissions. A pronounced bimodal CO2 diurnal profile was observed indicating the CO2 concentration is mainly related to the increase in traffic load during the rush hours.
Citation Format(s)
Atmospheric CO2 measurement using dispersive Infrared Spectroscopy with a scanning Fabry-Perot Interferometer Sensor. / Chan, Ka Lok; Ning, Zhi; Westerdahl, Dane et al.
EGU General Assembly 2014. Munich: European Geosciences Union, 2014. EGU2014-2937 (Geophysical Research Abstracts (GRA); Vol. 16).
EGU General Assembly 2014. Munich: European Geosciences Union, 2014. EGU2014-2937 (Geophysical Research Abstracts (GRA); Vol. 16).
Research output: Chapters, Conference Papers, Creative and Literary Works › RGC 32 - Refereed conference paper (with host publication) › peer-review