Measurement report: Radiative efficiencies of (CF<sub>3</sub>)<sub>2</sub>CFCN, CF<sub>3</sub>OCFCF<sub>2</sub>, and CF<sub>3</sub>OCF<sub>2</sub>CF<sub>3</sub>
<p>Absorption cross sections of emerging greenhouse gases (GHGs) were measured to estimate the radiative efficiency using high-resolution Fourier transform infrared spectroscopy (HR-FTIR). For quantitative spectroscopy, the Beer–Lambert parameters of absorber pressure, temperature, and optical...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/4489/2023/acp-23-4489-2023.pdf |
| Summary: | <p>Absorption cross sections of emerging greenhouse gases (GHGs) were measured to estimate the radiative efficiency using
high-resolution Fourier transform infrared spectroscopy (HR-FTIR). For
quantitative spectroscopy, the Beer–Lambert parameters of absorber
pressure, temperature, and optical path length (OPL) were accurately
determined to be traceable to the primary standards. The OPL of the
multipass cell mounted on the HR-FTIR spectrometer was spectroscopically
calibrated. A ratio of the averaged N<span class="inline-formula"><sub>2</sub></span>O absorptions was found to be in
the range of 2217.4–2219.0 cm<span class="inline-formula"><sup>−1</sup></span>, with a spectral resolution of 0.026 cm<span class="inline-formula"><sup>−1</sup></span>, yielding a ratio of OPLs between the multipass cell and reference cell. This cell-to-cell comparison method is free from the
uncertainty of the referring line strength, which reduced the calibration uncertainty compared with the direct line-strength referring method. With
the OPL-calibrated multipass cell (3.169 <span class="inline-formula">±</span> 0.079 m), the absorption
cross sections were measured at low absorber pressures with a spectral resolution of 2 cm<span class="inline-formula"><sup>−1</sup></span>, integrated at 10 cm<span class="inline-formula"><sup>−1</sup></span> intervals, and
multiplied by the new narrow band model to yield the radiative efficiencies.
The radiative efficiency values of CF<span class="inline-formula"><sub>4</sub></span>, SF<span class="inline-formula"><sub>6</sub></span>, and NF<span class="inline-formula"><sub>3</sub></span> were
evaluated to be 0.085 <span class="inline-formula">±</span> 0.002, 0.573 <span class="inline-formula">±</span> 0.016, and 0.195 <span class="inline-formula">±</span> 0.008 W m<span class="inline-formula"><sup>−2</sup></span> ppb<span class="inline-formula"><sup>−1</sup></span>, respectively, which are consistent with
previously reported values. For the emerging GHGs, the radiative efficiency
values were determined to be 0.201 <span class="inline-formula">±</span> 0.008 W m<span class="inline-formula"><sup>−2</sup></span> ppb<span class="inline-formula"><sup>−1</sup></span> for
heptafluoroisobutyronitrile (CF<span class="inline-formula"><sub>3</sub></span>)<span class="inline-formula"><sub>2</sub></span>CFCN; commercially referred to
as <i>Novec-4710</i>), 0.328 <span class="inline-formula">±</span> 0.013 W m<span class="inline-formula"><sup>−2</sup></span> ppb<span class="inline-formula"><sup>−1</sup></span> for perfluoro methyl vinyl
ether (CF<span class="inline-formula"><sub>3</sub></span>OCFCF<span class="inline-formula"><sub>2</sub></span>; PMVE), and 0.544 <span class="inline-formula">±</span> 0.022 W m<span class="inline-formula"><sup>−2</sup></span> ppb<span class="inline-formula"><sup>−1</sup></span> for 1,1,1,2,2-pentafluoro-2-(trifluoromethoxy)ethane
(CF<span class="inline-formula"><sub>3</sub></span>OCF<span class="inline-formula"><sub>2</sub></span>CF<span class="inline-formula"><sub>3</sub></span>; PFMEE).</p> |
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| ISSN: | 1680-7316 1680-7324 |