High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques
<p>Carbon dioxide and oxygen are tightly coupled in land biosphere <span class="inline-formula">CO<sub>2</sub></span>–<span class="inline-formula">O<sub>2</sub></span> exchange processes, whereas they are not coupled in oceani...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-12-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/12/6803/2019/amt-12-6803-2019.pdf |
| _version_ | 1818510841400524800 |
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| author | T. A. Berhanu T. A. Berhanu J. Hoffnagle C. Rella D. Kimhak P. Nyfeler M. Leuenberger |
| author_facet | T. A. Berhanu T. A. Berhanu J. Hoffnagle C. Rella D. Kimhak P. Nyfeler M. Leuenberger |
| author_sort | T. A. Berhanu |
| collection | DOAJ |
| description | <p>Carbon dioxide and oxygen are tightly coupled in land biosphere <span class="inline-formula">CO<sub>2</sub></span>–<span class="inline-formula">O<sub>2</sub></span> exchange processes, whereas they are not coupled in oceanic exchange.
For this reason, atmospheric oxygen measurements can be used to constrain
the global carbon cycle, especially oceanic uptake. However, accurately
quantifying small (<span class="inline-formula">∼1</span>–100 ppm) variations in <span class="inline-formula">O<sub>2</sub></span> is
analytically challenging due to the very large atmospheric background which
constitutes about 20.9 % (<span class="inline-formula">∼209 500</span> ppm) of atmospheric air.
Here we present a detailed description of a newly
developed high-precision oxygen mixing ratio and isotopic composition
analyzer (Picarro G2207) that is based on cavity ring-down spectroscopy
(CRDS) as well as to its operating
principles; we also demonstrate comprehensive laboratory and field studies using the abovementioned instrument. From the laboratory tests, we calculated a short-term precision
(standard error of 1 min <span class="inline-formula">O<sub>2</sub></span> mixing ratio measurements) of
< 1 ppm for this analyzer based on measurements of eight standard
gases analyzed for 2 h, respectively. In contrast to the currently
existing techniques, the instrument has an excellent long-term stability;
therefore, calibration every 12 h is sufficient to get an overall
uncertainty of < 5 ppm. Measurements of ambient air were also
conducted at the Jungfraujoch high-altitude research station and the
Beromünster tall tower in Switzerland. At both sites, we observed
opposing and diurnally varying <span class="inline-formula">CO<sub>2</sub></span> and <span class="inline-formula">O<sub>2</sub></span> profiles due to
different processes such as combustion, photosynthesis, and respiration.
Based on the combined measurements at Beromünster tower, we determined
height-dependent <span class="inline-formula">O<sub>2</sub>:CO<sub>2</sub></span> oxidation ratios varying between <span class="inline-formula">−0.98</span> and
<span class="inline-formula">−1.60</span>; these ratios increased with the height of the tower inlet, possibly due to
different source contributions such as natural gas combustion, which has a high
oxidation ratio, and biological processes, which have oxidation ratios that are relatively lower.</p> |
| first_indexed | 2024-12-10T23:25:38Z |
| format | Article |
| id | doaj.art-e07f75f9c04742978df20046b5fcb9de |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-10T23:25:38Z |
| publishDate | 2019-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-e07f75f9c04742978df20046b5fcb9de2022-12-22T01:29:36ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482019-12-01126803682610.5194/amt-12-6803-2019High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniquesT. A. Berhanu0T. A. Berhanu1J. Hoffnagle2C. Rella3D. Kimhak4P. Nyfeler5M. Leuenberger6Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandPicarro Inc., 3105 Patrick Henry Drive, Santa Clara, CA, USAPicarro Inc., 3105 Patrick Henry Drive, Santa Clara, CA, USAPicarro Inc., 3105 Patrick Henry Drive, Santa Clara, CA, USAPicarro Inc., 3105 Patrick Henry Drive, Santa Clara, CA, USAClimate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandClimate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland<p>Carbon dioxide and oxygen are tightly coupled in land biosphere <span class="inline-formula">CO<sub>2</sub></span>–<span class="inline-formula">O<sub>2</sub></span> exchange processes, whereas they are not coupled in oceanic exchange. For this reason, atmospheric oxygen measurements can be used to constrain the global carbon cycle, especially oceanic uptake. However, accurately quantifying small (<span class="inline-formula">∼1</span>–100 ppm) variations in <span class="inline-formula">O<sub>2</sub></span> is analytically challenging due to the very large atmospheric background which constitutes about 20.9 % (<span class="inline-formula">∼209 500</span> ppm) of atmospheric air. Here we present a detailed description of a newly developed high-precision oxygen mixing ratio and isotopic composition analyzer (Picarro G2207) that is based on cavity ring-down spectroscopy (CRDS) as well as to its operating principles; we also demonstrate comprehensive laboratory and field studies using the abovementioned instrument. From the laboratory tests, we calculated a short-term precision (standard error of 1 min <span class="inline-formula">O<sub>2</sub></span> mixing ratio measurements) of < 1 ppm for this analyzer based on measurements of eight standard gases analyzed for 2 h, respectively. In contrast to the currently existing techniques, the instrument has an excellent long-term stability; therefore, calibration every 12 h is sufficient to get an overall uncertainty of < 5 ppm. Measurements of ambient air were also conducted at the Jungfraujoch high-altitude research station and the Beromünster tall tower in Switzerland. At both sites, we observed opposing and diurnally varying <span class="inline-formula">CO<sub>2</sub></span> and <span class="inline-formula">O<sub>2</sub></span> profiles due to different processes such as combustion, photosynthesis, and respiration. Based on the combined measurements at Beromünster tower, we determined height-dependent <span class="inline-formula">O<sub>2</sub>:CO<sub>2</sub></span> oxidation ratios varying between <span class="inline-formula">−0.98</span> and <span class="inline-formula">−1.60</span>; these ratios increased with the height of the tower inlet, possibly due to different source contributions such as natural gas combustion, which has a high oxidation ratio, and biological processes, which have oxidation ratios that are relatively lower.</p>https://www.atmos-meas-tech.net/12/6803/2019/amt-12-6803-2019.pdf |
| spellingShingle | T. A. Berhanu T. A. Berhanu J. Hoffnagle C. Rella D. Kimhak P. Nyfeler M. Leuenberger High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques Atmospheric Measurement Techniques |
| title | High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques |
| title_full | High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques |
| title_fullStr | High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques |
| title_full_unstemmed | High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques |
| title_short | High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques |
| title_sort | high precision atmospheric oxygen measurement comparisons between a newly built crds analyzer and existing measurement techniques |
| url | https://www.atmos-meas-tech.net/12/6803/2019/amt-12-6803-2019.pdf |
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