Absorption instruments inter-comparison campaign at the Arctic Pallas station
<p>Aerosol light absorption was measured during a 1-month field campaign in June–July 2019 at the Pallas Global Atmospheric Watch (GAW) station in northern Finland. Very low aerosol concentrations prevailed during the campaign, which posed a challenge for the instruments' detection capabi...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-08-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/14/5397/2021/amt-14-5397-2021.pdf |
| _version_ | 1831650548012548096 |
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| author | E. Asmi J. Backman H. Servomaa A. Virkkula M. I. Gini K. Eleftheriadis T. Müller S. Ohata S. Ohata Y. Kondo A. Hyvärinen |
| author_facet | E. Asmi J. Backman H. Servomaa A. Virkkula M. I. Gini K. Eleftheriadis T. Müller S. Ohata S. Ohata Y. Kondo A. Hyvärinen |
| author_sort | E. Asmi |
| collection | DOAJ |
| description | <p>Aerosol light absorption was measured during a 1-month field campaign in June–July 2019 at the Pallas Global Atmospheric Watch (GAW) station in northern Finland. Very low aerosol concentrations prevailed during the campaign, which posed a challenge for the instruments' detection capabilities. The campaign provided a real-world test for different absorption measurement techniques supporting the goals of the European Metrology Programme for Innovation and Research (EMPIR) Black Carbon (BC) project in developing aerosol absorption standard and reference methods. In this study we compare the results from five filter-based absorption techniques – aethalometer models AE31 and AE33, a particle soot absorption photometer (PSAP), a multi-angle absorption photometer (MAAP), and a continuous soot monitoring system (COSMOS) – and from one indirect technique called extinction minus scattering (EMS). The ability of the filter-based techniques was shown to be adequate to measure aerosol light absorption coefficients down to around 0.01 <span class="inline-formula">Mm<sup>−1</sup></span> levels when data were averaged to 1–2 h. The hourly averaged atmospheric absorption measured by the reference MAAP was 0.09 <span class="inline-formula">Mm<sup>−1</sup></span> (at a wavelength of 637 nm). When data were averaged for <span class="inline-formula">>1</span> h, the filter-based methods agreed to around 40 %. COSMOS systematically measured the lowest absorption coefficient values, which was expected due to the sample pre-treatment in the COSMOS inlet. PSAP showed the best linear correlation with MAAP (<span class="inline-formula">slope=0.95</span>, <span class="inline-formula"><i>R</i><sup>2</sup>=0.78</span>), followed by AE31 (<span class="inline-formula">slope=0.93</span>). A scattering correction applied to PSAP data improved the data accuracy despite the added noise. However, at very high scattering values the correction led to an underestimation of the absorption. The AE31 data had the highest noise and the correlation with MAAP was the lowest (<span class="inline-formula"><i>R</i><sup>2</sup>=0.65</span>). Statistically the best linear correlations with MAAP were obtained for AE33 and COSMOS (<span class="inline-formula"><i>R</i><sup>2</sup></span> close to 1), but the biases at around the zero values led to slopes clearly below 1. The sample pre-treatment in the COSMOS instrument resulted in the lowest fitted slope. In contrast to the filter-based techniques, the indirect EMS method was not adequate to measure the low absorption values found at the Pallas site. The lowest absorption at which the EMS signal could be distinguished from the noise was <span class="inline-formula">>0.1</span> <span class="inline-formula">Mm<sup>−1</sup></span> at 1–2 h averaging times. The mass absorption cross section (MAC) value measured at a range 0–0.3 <span class="inline-formula">Mm<sup>−1</sup></span> was calculated using the MAAP and a single particle soot photometer (SP2), resulting in a MAC value of <span class="inline-formula">16.0±5.7</span> <span class="inline-formula">m<sup>2</sup> g<sup>−1</sup></span>. Overall, our results demonstrate the challenges encountered in the aerosol absorption measurements in pristine environments and provide some useful guidelines for instrument selection and measurement practices. We highlight the need for a calibrated transfer standard for better inter-comparability of the absorption results.</p> |
| first_indexed | 2024-12-19T15:11:51Z |
| format | Article |
| id | doaj.art-e87ee00b4aac44f0b0ea90561d047508 |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-19T15:11:51Z |
| publishDate | 2021-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-e87ee00b4aac44f0b0ea90561d0475082022-12-21T20:16:17ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482021-08-01145397541310.5194/amt-14-5397-2021Absorption instruments inter-comparison campaign at the Arctic Pallas stationE. Asmi0J. Backman1H. Servomaa2A. Virkkula3M. I. Gini4K. Eleftheriadis5T. Müller6S. Ohata7S. Ohata8Y. Kondo9A. Hyvärinen10Finnish Meteorological Institute, Helsinki, FinlandFinnish Meteorological Institute, Helsinki, FinlandFinnish Meteorological Institute, Helsinki, FinlandFinnish Meteorological Institute, Helsinki, FinlandEnvironmental Radioactivity Laboratory, INRaSTES, NCSR Demokritos, Athens, GreeceEnvironmental Radioactivity Laboratory, INRaSTES, NCSR Demokritos, Athens, GreeceLeibniz Institute for Tropospheric Research e.V. (TROPOS), Leipzig, GermanyInstitute for Space–Earth Environmental Research, Nagoya University, Nagoya, Aichi, JapanInstitute for Advanced Research, Nagoya University, Nagoya, Aichi, JapanNational Institute of Polar Research, Tachikawa, JapanFinnish Meteorological Institute, Helsinki, Finland<p>Aerosol light absorption was measured during a 1-month field campaign in June–July 2019 at the Pallas Global Atmospheric Watch (GAW) station in northern Finland. Very low aerosol concentrations prevailed during the campaign, which posed a challenge for the instruments' detection capabilities. The campaign provided a real-world test for different absorption measurement techniques supporting the goals of the European Metrology Programme for Innovation and Research (EMPIR) Black Carbon (BC) project in developing aerosol absorption standard and reference methods. In this study we compare the results from five filter-based absorption techniques – aethalometer models AE31 and AE33, a particle soot absorption photometer (PSAP), a multi-angle absorption photometer (MAAP), and a continuous soot monitoring system (COSMOS) – and from one indirect technique called extinction minus scattering (EMS). The ability of the filter-based techniques was shown to be adequate to measure aerosol light absorption coefficients down to around 0.01 <span class="inline-formula">Mm<sup>−1</sup></span> levels when data were averaged to 1–2 h. The hourly averaged atmospheric absorption measured by the reference MAAP was 0.09 <span class="inline-formula">Mm<sup>−1</sup></span> (at a wavelength of 637 nm). When data were averaged for <span class="inline-formula">>1</span> h, the filter-based methods agreed to around 40 %. COSMOS systematically measured the lowest absorption coefficient values, which was expected due to the sample pre-treatment in the COSMOS inlet. PSAP showed the best linear correlation with MAAP (<span class="inline-formula">slope=0.95</span>, <span class="inline-formula"><i>R</i><sup>2</sup>=0.78</span>), followed by AE31 (<span class="inline-formula">slope=0.93</span>). A scattering correction applied to PSAP data improved the data accuracy despite the added noise. However, at very high scattering values the correction led to an underestimation of the absorption. The AE31 data had the highest noise and the correlation with MAAP was the lowest (<span class="inline-formula"><i>R</i><sup>2</sup>=0.65</span>). Statistically the best linear correlations with MAAP were obtained for AE33 and COSMOS (<span class="inline-formula"><i>R</i><sup>2</sup></span> close to 1), but the biases at around the zero values led to slopes clearly below 1. The sample pre-treatment in the COSMOS instrument resulted in the lowest fitted slope. In contrast to the filter-based techniques, the indirect EMS method was not adequate to measure the low absorption values found at the Pallas site. The lowest absorption at which the EMS signal could be distinguished from the noise was <span class="inline-formula">>0.1</span> <span class="inline-formula">Mm<sup>−1</sup></span> at 1–2 h averaging times. The mass absorption cross section (MAC) value measured at a range 0–0.3 <span class="inline-formula">Mm<sup>−1</sup></span> was calculated using the MAAP and a single particle soot photometer (SP2), resulting in a MAC value of <span class="inline-formula">16.0±5.7</span> <span class="inline-formula">m<sup>2</sup> g<sup>−1</sup></span>. Overall, our results demonstrate the challenges encountered in the aerosol absorption measurements in pristine environments and provide some useful guidelines for instrument selection and measurement practices. We highlight the need for a calibrated transfer standard for better inter-comparability of the absorption results.</p>https://amt.copernicus.org/articles/14/5397/2021/amt-14-5397-2021.pdf |
| spellingShingle | E. Asmi J. Backman H. Servomaa A. Virkkula M. I. Gini K. Eleftheriadis T. Müller S. Ohata S. Ohata Y. Kondo A. Hyvärinen Absorption instruments inter-comparison campaign at the Arctic Pallas station Atmospheric Measurement Techniques |
| title | Absorption instruments inter-comparison campaign at the Arctic Pallas station |
| title_full | Absorption instruments inter-comparison campaign at the Arctic Pallas station |
| title_fullStr | Absorption instruments inter-comparison campaign at the Arctic Pallas station |
| title_full_unstemmed | Absorption instruments inter-comparison campaign at the Arctic Pallas station |
| title_short | Absorption instruments inter-comparison campaign at the Arctic Pallas station |
| title_sort | absorption instruments inter comparison campaign at the arctic pallas station |
| url | https://amt.copernicus.org/articles/14/5397/2021/amt-14-5397-2021.pdf |
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