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Plane, JMC orcid.org/0000-0003-3648-6893, Feng, W orcid.org/0000-0002-9907-9120, Carlos Gómez Martín, J et al. (2 more authors) (2018) A new model of meteoric calcium in the mesosphere and lower thermosphere. Atmospheric Chemistry and Physics, 18 (20). pp. 14799-14811. ISSN 1680-7316
Abstract
Meteoric ablation produces layers of metal atoms in the mesosphere and lower thermosphere (MLT). It has been known for more than 30 years that the Ca atom layer is depleted by over 2 orders of magnitude compared with Na, despite these elements having nearly the same elemental abundance in chondritic meteorites. In contrast, the Ca+ ion abundance is depleted by less than a factor of 10. To explain these observations, a large database of neutral and ion–molecule reaction kinetics of Ca species, measured over the past decade, was incorporated into the Whole Atmosphere Community Climate Model (WACCM). A new meteoric input function for Ca and Na, derived using a chemical ablation model that has been tested experimentally with a Meteoric Ablation Simulator, shows that Ca ablates almost 1 order of magnitude less efficiently than Na. WACCM-Ca simulates the seasonal Ca layer satisfactorily when compared with lidar observations, but tends to overestimate Ca+ measurements made by rocket mass spectrometry and lidar. A key finding is that CaOH and CaCO3 are very stable reservoir species because they are involved in essentially closed reaction cycles with O2 and O. This has been demonstrated experimentally for CaOH, and in this study for CaCO3 using electronic structure and statistical rate theory. Most of the neutral Ca is therefore locked in these reservoirs, enabling rapid loss through polymerization into meteoric smoke particles, and this explains the extreme depletion of Ca.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. (https://creativecommons.org/licenses/by/4.0/) |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Physical Chemistry (Leeds) The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > National Centre for Atmos Science (NCAS) (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) |
Funding Information: | Funder Grant number EU - European Union 291332 |
Depositing User: | Symplectic Publications |
Date Deposited: | 05 Nov 2018 11:19 |
Last Modified: | 18 Jul 2020 19:09 |
Status: | Published |
Publisher: | European Geosciences Union |
Identification Number: | 10.5194/acp-18-14799-2018 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:138151 |
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A new model of meteoric calcium in the mesosphere and lower thermosphere. (deposited 12 Dec 2019 16:10)
- A new model of meteoric calcium in the mesosphere and lower thermosphere. (deposited 05 Nov 2018 11:19) [Currently Displayed]
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