Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experiments
<p>Atmospheric aerosol particles are the precondition for the formation of cloud droplets and therefore have large influence on the microphysical and radiative properties of clouds. In this work, four different methods to derive or measure number concentrations of cloud condensation nuclei (CC...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2020-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/20/8787/2020/acp-20-8787-2020.pdf |
| _version_ | 1818068144066920448 |
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| author | C. Genz C. Genz C. Genz R. Schrödner B. Heinold S. Henning H. Baars G. Spindler I. Tegen |
| author_facet | C. Genz C. Genz C. Genz R. Schrödner B. Heinold S. Henning H. Baars G. Spindler I. Tegen |
| author_sort | C. Genz |
| collection | DOAJ |
| description | <p>Atmospheric aerosol particles are the precondition for the formation of cloud droplets and therefore have large influence on the microphysical and radiative properties of clouds. In this work, four different methods to derive or measure number concentrations of cloud condensation nuclei (CCN) were analyzed and compared for present-day aerosol conditions: (i) a model parameterization based on simulated particle concentrations, (ii) the same parameterization based on gravimetrical particle measurements, (iii) direct CCN measurements with a CCN counter, and (iv) lidar-derived and in situ measured vertical CCN profiles. In order to allow for sensitivity studies of the anthropogenic impact, a scenario to estimate the maximum CCN concentration under peak aerosol conditions of the mid-1980s in Europe was developed as well. In general, the simulations are in good agreement with the observations. At ground level, average values between 0.7 and <span class="inline-formula">1.5×10<sup>9</sup></span> <span class="inline-formula">CCN m<sup>−3</sup></span> at a supersaturation of 0.2 % were found with the different methods under present-day conditions. The discrimination of the chemical species revealed an almost equal contribution of ammonium sulfate and ammonium nitrate to the total number of CCN for present-day conditions. This was not the case for the peak aerosol scenario, in which it was assumed that no ammonium nitrate was formed while large amounts of sulfate were present, consuming all available ammonia during ammonium sulfate formation. The CCN number concentration at five different supersaturation values has been compared to the measurements. The discrepancies between model and in situ observations were lowest for the lowest (0.1 %) and highest supersaturations (0.7 %). For supersaturations between 0.3 % and 0.5 %, the model overestimated the potentially activated particle fraction by around 30 %. By comparing the simulation with observed profiles, the vertical distribution of the CCN concentration was found to be overestimated by up to a factor of 2 in the boundary layer. The analysis of the modern (year 2013) and the peak aerosol scenario (expected to be representative of the mid-1980s over Europe) resulted in a scaling factor, which was defined as the quotient of the average vertical profile of the peak aerosol and present-day CCN concentration. This factor was found to be around 2 close to the ground, increasing to around 3.5 between 2 and 5 <span class="inline-formula">km</span> and approaching 1 (i.e., no difference between present-day and peak aerosol conditions) with further increasing height.</p> |
| first_indexed | 2024-12-10T15:34:54Z |
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| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-10T15:34:54Z |
| publishDate | 2020-07-01 |
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| spelling | doaj.art-fedbda177cbb4826b355ad97b9aa0f962022-12-22T01:43:16ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242020-07-01208787880610.5194/acp-20-8787-2020Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experimentsC. Genz0C. Genz1C. Genz2R. Schrödner3B. Heinold4S. Henning5H. Baars6G. Spindler7I. Tegen8Leibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Germanynow at: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04317 Leipzig, Germanypreviously published under the name Christa EnglerLeibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, GermanyLeibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, GermanyLeibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, GermanyLeibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, GermanyLeibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, GermanyLeibniz Institute for Tropospheric Research (TROPOS), Permoserstraße 15, 04318 Leipzig, Germany<p>Atmospheric aerosol particles are the precondition for the formation of cloud droplets and therefore have large influence on the microphysical and radiative properties of clouds. In this work, four different methods to derive or measure number concentrations of cloud condensation nuclei (CCN) were analyzed and compared for present-day aerosol conditions: (i) a model parameterization based on simulated particle concentrations, (ii) the same parameterization based on gravimetrical particle measurements, (iii) direct CCN measurements with a CCN counter, and (iv) lidar-derived and in situ measured vertical CCN profiles. In order to allow for sensitivity studies of the anthropogenic impact, a scenario to estimate the maximum CCN concentration under peak aerosol conditions of the mid-1980s in Europe was developed as well. In general, the simulations are in good agreement with the observations. At ground level, average values between 0.7 and <span class="inline-formula">1.5×10<sup>9</sup></span> <span class="inline-formula">CCN m<sup>−3</sup></span> at a supersaturation of 0.2 % were found with the different methods under present-day conditions. The discrimination of the chemical species revealed an almost equal contribution of ammonium sulfate and ammonium nitrate to the total number of CCN for present-day conditions. This was not the case for the peak aerosol scenario, in which it was assumed that no ammonium nitrate was formed while large amounts of sulfate were present, consuming all available ammonia during ammonium sulfate formation. The CCN number concentration at five different supersaturation values has been compared to the measurements. The discrepancies between model and in situ observations were lowest for the lowest (0.1 %) and highest supersaturations (0.7 %). For supersaturations between 0.3 % and 0.5 %, the model overestimated the potentially activated particle fraction by around 30 %. By comparing the simulation with observed profiles, the vertical distribution of the CCN concentration was found to be overestimated by up to a factor of 2 in the boundary layer. The analysis of the modern (year 2013) and the peak aerosol scenario (expected to be representative of the mid-1980s over Europe) resulted in a scaling factor, which was defined as the quotient of the average vertical profile of the peak aerosol and present-day CCN concentration. This factor was found to be around 2 close to the ground, increasing to around 3.5 between 2 and 5 <span class="inline-formula">km</span> and approaching 1 (i.e., no difference between present-day and peak aerosol conditions) with further increasing height.</p>https://www.atmos-chem-phys.net/20/8787/2020/acp-20-8787-2020.pdf |
| spellingShingle | C. Genz C. Genz C. Genz R. Schrödner B. Heinold S. Henning H. Baars G. Spindler I. Tegen Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experiments Atmospheric Chemistry and Physics |
| title | Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experiments |
| title_full | Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experiments |
| title_fullStr | Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experiments |
| title_full_unstemmed | Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experiments |
| title_short | Estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the HOPE experiments |
| title_sort | estimation of cloud condensation nuclei number concentrations and comparison to in situ and lidar observations during the hope experiments |
| url | https://www.atmos-chem-phys.net/20/8787/2020/acp-20-8787-2020.pdf |
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