Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations
The accurate measurement of greenhouse gas emissions is a challenge for atmospheric science. Long-range open-path sensors are flexible enough to be applied to a variety of complex emission sources, and single devices are often used to measure both high and low path-integrated concentrations. As this...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-02-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/11/2/184 |
| _version_ | 1819213001851404288 |
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| author | Zachary J. DeBruyn Claudia Wagner-Riddle Andrew VanderZaag |
| author_facet | Zachary J. DeBruyn Claudia Wagner-Riddle Andrew VanderZaag |
| author_sort | Zachary J. DeBruyn |
| collection | DOAJ |
| description | The accurate measurement of greenhouse gas emissions is a challenge for atmospheric science. Long-range open-path sensors are flexible enough to be applied to a variety of complex emission sources, and single devices are often used to measure both high and low path-integrated concentrations. As this technology develops, it is important to examine potential sources of inaccuracy. A GasFinder3 open-path laser was tested with a range of path-integrated concentrations from 11.7 to 182 ppm∙m CH<sub>4</sub> using certified standard gases. The measured path-integrated concentrations had a positive bias which was higher than 10% at low path-integrated concentrations (<50 ppm∙m) with a declining trend expected to be under 2% at 200 ppm∙m. A linear equation was used to correct the measured path-integrated concentrations to fit the expected values. After correction, the average bias was reduced to −0.36% and there was no relationship with path-integrated concentration. A relative bias less than ±3% was achieved above ca. 150 ppm∙m with or without calibration. Measurement campaigns may reduce error by increasing path lengths to maximize path-integrated concentration. When low path-integrated concentrations are expected, calibration over the expected range is beneficial. |
| first_indexed | 2024-12-23T06:51:55Z |
| format | Article |
| id | doaj.art-c7461a9b56e74c13be3bc35bae107ce2 |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-12-23T06:51:55Z |
| publishDate | 2020-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-c7461a9b56e74c13be3bc35bae107ce22022-12-21T17:56:25ZengMDPI AGAtmosphere2073-44332020-02-0111218410.3390/atmos11020184atmos11020184Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane ConcentrationsZachary J. DeBruyn0Claudia Wagner-Riddle1Andrew VanderZaag2Former Graduate Student at School of Environmental Sciences, University of Guelph, 50 Stone Road E, Guelph, ON N1G2W1, CanadaSchool of Environmental Sciences, University of Guelph, 50 Stone Road E, Guelph, ON N1G2W1, CanadaOttawa Research and Development Centre, Science and Technology Branch, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A0C6, CanadaThe accurate measurement of greenhouse gas emissions is a challenge for atmospheric science. Long-range open-path sensors are flexible enough to be applied to a variety of complex emission sources, and single devices are often used to measure both high and low path-integrated concentrations. As this technology develops, it is important to examine potential sources of inaccuracy. A GasFinder3 open-path laser was tested with a range of path-integrated concentrations from 11.7 to 182 ppm∙m CH<sub>4</sub> using certified standard gases. The measured path-integrated concentrations had a positive bias which was higher than 10% at low path-integrated concentrations (<50 ppm∙m) with a declining trend expected to be under 2% at 200 ppm∙m. A linear equation was used to correct the measured path-integrated concentrations to fit the expected values. After correction, the average bias was reduced to −0.36% and there was no relationship with path-integrated concentration. A relative bias less than ±3% was achieved above ca. 150 ppm∙m with or without calibration. Measurement campaigns may reduce error by increasing path lengths to maximize path-integrated concentration. When low path-integrated concentrations are expected, calibration over the expected range is beneficial.https://www.mdpi.com/2073-4433/11/2/184open-path lasermethanepath-integrated concentrationgasfinder3 |
| spellingShingle | Zachary J. DeBruyn Claudia Wagner-Riddle Andrew VanderZaag Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations Atmosphere open-path laser methane path-integrated concentration gasfinder3 |
| title | Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations |
| title_full | Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations |
| title_fullStr | Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations |
| title_full_unstemmed | Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations |
| title_short | Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations |
| title_sort | assessment of open path spectrometer accuracy at low path integrated methane concentrations |
| topic | open-path laser methane path-integrated concentration gasfinder3 |
| url | https://www.mdpi.com/2073-4433/11/2/184 |
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