Differences in microphysical properties of cirrus at high and mid-latitudes
<p>Despite their proven importance for the atmospheric radiative energy budget, the effect of cirrus on climate and the magnitude of their modification by human activity is not well quantified. Besides anthropogenic pollution sources on the ground, aviation has a large local effect on cirrus m...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-10-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/13167/2023/acp-23-13167-2023.pdf |
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| author | E. De La Torre Castro E. De La Torre Castro E. De La Torre Castro T. Jurkat-Witschas A. Afchine V. Grewe V. Grewe V. Hahn V. Hahn S. Kirschler S. Kirschler M. Krämer M. Krämer J. Lucke J. Lucke N. Spelten H. Wernli M. Zöger C. Voigt C. Voigt |
| author_facet | E. De La Torre Castro E. De La Torre Castro E. De La Torre Castro T. Jurkat-Witschas A. Afchine V. Grewe V. Grewe V. Hahn V. Hahn S. Kirschler S. Kirschler M. Krämer M. Krämer J. Lucke J. Lucke N. Spelten H. Wernli M. Zöger C. Voigt C. Voigt |
| author_sort | E. De La Torre Castro |
| collection | DOAJ |
| description | <p>Despite their proven importance for the atmospheric radiative energy budget, the effect of cirrus on climate and the magnitude of their modification by human activity is not well quantified. Besides anthropogenic pollution sources on the ground, aviation has a large local effect on cirrus microphysical and radiative properties via the formation of contrails and their transition to contrail cirrus. To investigate the anthropogenic influence on natural cirrus, we compare the microphysical properties of cirrus measured at mid-latitude (ML) regions (<span class="inline-formula"><60</span><span class="inline-formula"><sup>∘</sup></span> N) that are often affected by aviation and pollution with cirrus measured in the same season in comparatively pristine high latitudes (HLs; <span class="inline-formula">≥60</span><span class="inline-formula"><sup>∘</sup></span> N). The number concentration, effective diameter, and ice water content of the observed cirrus are derived from in situ measurements covering ice crystal sizes between 2 and 6400 <span class="inline-formula">µm</span> collected during the CIRRUS-HL campaign (Cirrus in High Latitudes) in June and July 2021. We analyse the dependence of cirrus microphysical properties on altitude and latitude and demonstrate that the median ice number concentration is an order of magnitude larger in the measured mid-latitude cirrus, with 0.0086 <span class="inline-formula">cm<sup>−3</sup></span>, compared to the high-latitude cirrus, with 0.001 <span class="inline-formula">cm<sup>−3</sup></span>. Ice crystals in mid-latitude cirrus are on average smaller than in high-latitude cirrus, with a median effective diameter of 165 <span class="inline-formula">µm</span> compared to 210 <span class="inline-formula">µm</span>, and the median ice water content in mid-latitude cirrus is higher (0.0033 <span class="inline-formula">g m<sup>−3</sup></span>) than in high-latitude cirrus (0.0019 <span class="inline-formula">g m<sup>−3</sup></span>). In order to investigate the cirrus properties in relation to the region of formation, we combine the airborne observations with 10 d backward trajectories to identify the location of cirrus formation and the cirrus type, i.e. in situ or liquid origin cirrus, depending on whether there is only ice or also liquid water present in the cirrus history, respectively. The cirrus formed and measured at mid-latitudes (M–M) have a particularly high ice number concentration and low effective diameter. This is very likely a signature of contrails and contrail cirrus, which is often observed in the in situ origin cirrus type. In contrast, the largest effective diameter and lowest number concentration were found in the cirrus formed and measured at high latitudes (H–H) along with the highest relative humidity over ice (<span class="inline-formula">RH<sub>i</sub></span>). On average, in-cloud <span class="inline-formula">RH<sub>i</sub></span> was above saturation in all cirrus. While most of the H–H cirrus were of an in situ origin, the cirrus formed at mid-latitudes and measured at high latitudes (M–H) were mainly of liquid origin. A pristine Arctic background atmosphere with relatively low ice nuclei availability and the extended growth of few nucleated ice crystals may explain the observed <span class="inline-formula">RH<sub>i</sub></span> and size distributions. The M–H cirrus are a mixture of the properties of M–M and H–H cirrus (preserving some of the initial properties acquired at mid-latitudes and transforming under Arctic atmospheric conditions). Our analyses indicate that part of the cirrus found at high latitudes is actually formed at mid-latitudes and therefore affected by mid-latitude air masses, which have a greater anthropogenic influence.</p> |
| first_indexed | 2024-03-11T17:40:25Z |
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| id | doaj.art-ffca93cdc62945b088acb2cfca8aa5dc |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-03-11T17:40:25Z |
| publishDate | 2023-10-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-ffca93cdc62945b088acb2cfca8aa5dc2023-10-18T14:13:14ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242023-10-0123131671318910.5194/acp-23-13167-2023Differences in microphysical properties of cirrus at high and mid-latitudesE. De La Torre Castro0E. De La Torre Castro1E. De La Torre Castro2T. Jurkat-Witschas3A. Afchine4V. Grewe5V. Grewe6V. Hahn7V. Hahn8S. Kirschler9S. Kirschler10M. Krämer11M. Krämer12J. Lucke13J. Lucke14N. Spelten15H. Wernli16M. Zöger17C. Voigt18C. Voigt19Institute of Atmospheric Physics, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyInstitute of Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyFaculty of Aerospace Engineering, Delft University of Technology, Delft, the NetherlandsInstitute of Atmospheric Physics, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyInstitute for Energy and Climate Research, Research Center Jülich, Jülich, GermanyInstitute of Atmospheric Physics, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyFaculty of Aerospace Engineering, Delft University of Technology, Delft, the NetherlandsInstitute of Atmospheric Physics, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyInstitute of Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyInstitute of Atmospheric Physics, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyInstitute of Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyInstitute of Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, GermanyInstitute for Energy and Climate Research, Research Center Jülich, Jülich, GermanyInstitute of Atmospheric Physics, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyFaculty of Aerospace Engineering, Delft University of Technology, Delft, the NetherlandsInstitute for Energy and Climate Research, Research Center Jülich, Jülich, GermanyInstitute for Atmospheric and Climate Science, ETH Zürich, Zurich, SwitzerlandInstitute for Flight Experiments, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyInstitute of Atmospheric Physics, German Aerospace Center, DLR, Oberpfaffenhofen, GermanyInstitute of Atmospheric Physics, Johannes Gutenberg University Mainz, Mainz, Germany<p>Despite their proven importance for the atmospheric radiative energy budget, the effect of cirrus on climate and the magnitude of their modification by human activity is not well quantified. Besides anthropogenic pollution sources on the ground, aviation has a large local effect on cirrus microphysical and radiative properties via the formation of contrails and their transition to contrail cirrus. To investigate the anthropogenic influence on natural cirrus, we compare the microphysical properties of cirrus measured at mid-latitude (ML) regions (<span class="inline-formula"><60</span><span class="inline-formula"><sup>∘</sup></span> N) that are often affected by aviation and pollution with cirrus measured in the same season in comparatively pristine high latitudes (HLs; <span class="inline-formula">≥60</span><span class="inline-formula"><sup>∘</sup></span> N). The number concentration, effective diameter, and ice water content of the observed cirrus are derived from in situ measurements covering ice crystal sizes between 2 and 6400 <span class="inline-formula">µm</span> collected during the CIRRUS-HL campaign (Cirrus in High Latitudes) in June and July 2021. We analyse the dependence of cirrus microphysical properties on altitude and latitude and demonstrate that the median ice number concentration is an order of magnitude larger in the measured mid-latitude cirrus, with 0.0086 <span class="inline-formula">cm<sup>−3</sup></span>, compared to the high-latitude cirrus, with 0.001 <span class="inline-formula">cm<sup>−3</sup></span>. Ice crystals in mid-latitude cirrus are on average smaller than in high-latitude cirrus, with a median effective diameter of 165 <span class="inline-formula">µm</span> compared to 210 <span class="inline-formula">µm</span>, and the median ice water content in mid-latitude cirrus is higher (0.0033 <span class="inline-formula">g m<sup>−3</sup></span>) than in high-latitude cirrus (0.0019 <span class="inline-formula">g m<sup>−3</sup></span>). In order to investigate the cirrus properties in relation to the region of formation, we combine the airborne observations with 10 d backward trajectories to identify the location of cirrus formation and the cirrus type, i.e. in situ or liquid origin cirrus, depending on whether there is only ice or also liquid water present in the cirrus history, respectively. The cirrus formed and measured at mid-latitudes (M–M) have a particularly high ice number concentration and low effective diameter. This is very likely a signature of contrails and contrail cirrus, which is often observed in the in situ origin cirrus type. In contrast, the largest effective diameter and lowest number concentration were found in the cirrus formed and measured at high latitudes (H–H) along with the highest relative humidity over ice (<span class="inline-formula">RH<sub>i</sub></span>). On average, in-cloud <span class="inline-formula">RH<sub>i</sub></span> was above saturation in all cirrus. While most of the H–H cirrus were of an in situ origin, the cirrus formed at mid-latitudes and measured at high latitudes (M–H) were mainly of liquid origin. A pristine Arctic background atmosphere with relatively low ice nuclei availability and the extended growth of few nucleated ice crystals may explain the observed <span class="inline-formula">RH<sub>i</sub></span> and size distributions. The M–H cirrus are a mixture of the properties of M–M and H–H cirrus (preserving some of the initial properties acquired at mid-latitudes and transforming under Arctic atmospheric conditions). Our analyses indicate that part of the cirrus found at high latitudes is actually formed at mid-latitudes and therefore affected by mid-latitude air masses, which have a greater anthropogenic influence.</p>https://acp.copernicus.org/articles/23/13167/2023/acp-23-13167-2023.pdf |
| spellingShingle | E. De La Torre Castro E. De La Torre Castro E. De La Torre Castro T. Jurkat-Witschas A. Afchine V. Grewe V. Grewe V. Hahn V. Hahn S. Kirschler S. Kirschler M. Krämer M. Krämer J. Lucke J. Lucke N. Spelten H. Wernli M. Zöger C. Voigt C. Voigt Differences in microphysical properties of cirrus at high and mid-latitudes Atmospheric Chemistry and Physics |
| title | Differences in microphysical properties of cirrus at high and mid-latitudes |
| title_full | Differences in microphysical properties of cirrus at high and mid-latitudes |
| title_fullStr | Differences in microphysical properties of cirrus at high and mid-latitudes |
| title_full_unstemmed | Differences in microphysical properties of cirrus at high and mid-latitudes |
| title_short | Differences in microphysical properties of cirrus at high and mid-latitudes |
| title_sort | differences in microphysical properties of cirrus at high and mid latitudes |
| url | https://acp.copernicus.org/articles/23/13167/2023/acp-23-13167-2023.pdf |
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