Observation of CO2++ dication in the dayside Martian upper atmosphere
Doubly charged positive ions (dications) are an important component of planetary ionospheres because of the large energy required for their formation. Observations of these ions are exceptionally difficult due to their low abundances; until now, only atomic dications have been detected. The Neutral...
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Science Press
2020-07-01
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| Series: | Earth and Planetary Physics |
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| Online Access: | http://www.eppcgs.org/article/doi/10.26464/epp2020036?pageType=en |
| _version_ | 1811218717627908096 |
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| author | Hao Gu Jun Cui DanDan Niu LongKang Dai JianPing Huang XiaoShu Wu YongQiang Hao Yong Wei |
| author_facet | Hao Gu Jun Cui DanDan Niu LongKang Dai JianPing Huang XiaoShu Wu YongQiang Hao Yong Wei |
| author_sort | Hao Gu |
| collection | DOAJ |
| description | Doubly charged positive ions (dications) are an important component of planetary ionospheres because of the large energy required for their formation. Observations of these ions are exceptionally difficult due to their low abundances; until now, only atomic dications have been detected. The Neutral Gas and Ion Mass Spectrometer (NGIMS) measurements made on board the recent Mars Atmosphere and Volatile Evolution mission provide the first opportunity for decisive detection of molecular dications, CO2++ in this case, in a planetary upper atmosphere. The NGIMS data reveal a dayside averaged CO2++ distribution declining steadily from 5.6 cm−3 at 160 km to below 1 cm−3 above 200 km. The dominant CO2++ production mechanisms are double photoionization of CO2 below 190 km and single photoionization of CO2+ at higher altitudes; CO2++ destruction is dominated by natural dissociation, but reactions with atmospheric CO2 and O become important below 160 km. Simplified photochemical model calculations are carried out and reasonably reproduce the data at low altitudes within a factor of 2 but underestimate the data at high altitudes by a factor of 4. Finally, we report a much stronger solar control of the CO2++ density than of the CO2+ density . |
| first_indexed | 2024-04-12T07:14:07Z |
| format | Article |
| id | doaj.art-9d2d53dc9e1c4a52b9a251d4f4316e2a |
| institution | Directory Open Access Journal |
| issn | 2096-3955 |
| language | English |
| last_indexed | 2024-04-12T07:14:07Z |
| publishDate | 2020-07-01 |
| publisher | Science Press |
| record_format | Article |
| series | Earth and Planetary Physics |
| spelling | doaj.art-9d2d53dc9e1c4a52b9a251d4f4316e2a2022-12-22T03:42:33ZengScience PressEarth and Planetary Physics2096-39552020-07-014439640210.26464/epp2020036guhao-cuijun12Observation of CO2++ dication in the dayside Martian upper atmosphereHao Gu0Jun Cui1DanDan Niu2LongKang Dai3JianPing Huang4XiaoShu Wu5YongQiang Hao6Yong Wei7State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau 999078, ChinaSchool of Atmospheric Sciences, Sun Yat-Sen University, Zhuhai Guangdong 519082, ChinaState Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau 999078, ChinaSchool of Atmospheric Sciences, Sun Yat-Sen University, Zhuhai Guangdong 519082, ChinaSchool of Atmospheric Sciences, Sun Yat-Sen University, Zhuhai Guangdong 519082, ChinaKey Laboratory of Lunar and Deep Space Exploration, Chinese Academy of Sciences, Beijing 100101, ChinaSchool of Earth and Space Sciences, Beijing University, Beijing 100871, ChinaInstitute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaDoubly charged positive ions (dications) are an important component of planetary ionospheres because of the large energy required for their formation. Observations of these ions are exceptionally difficult due to their low abundances; until now, only atomic dications have been detected. The Neutral Gas and Ion Mass Spectrometer (NGIMS) measurements made on board the recent Mars Atmosphere and Volatile Evolution mission provide the first opportunity for decisive detection of molecular dications, CO2++ in this case, in a planetary upper atmosphere. The NGIMS data reveal a dayside averaged CO2++ distribution declining steadily from 5.6 cm−3 at 160 km to below 1 cm−3 above 200 km. The dominant CO2++ production mechanisms are double photoionization of CO2 below 190 km and single photoionization of CO2+ at higher altitudes; CO2++ destruction is dominated by natural dissociation, but reactions with atmospheric CO2 and O become important below 160 km. Simplified photochemical model calculations are carried out and reasonably reproduce the data at low altitudes within a factor of 2 but underestimate the data at high altitudes by a factor of 4. Finally, we report a much stronger solar control of the CO2++ density than of the CO2+ density .http://www.eppcgs.org/article/doi/10.26464/epp2020036?pageType=enmavenmartian ionospheredication |
| spellingShingle | Hao Gu Jun Cui DanDan Niu LongKang Dai JianPing Huang XiaoShu Wu YongQiang Hao Yong Wei Observation of CO2++ dication in the dayside Martian upper atmosphere Earth and Planetary Physics maven martian ionosphere dication |
| title | Observation of CO2++ dication in the dayside Martian upper atmosphere |
| title_full | Observation of CO2++ dication in the dayside Martian upper atmosphere |
| title_fullStr | Observation of CO2++ dication in the dayside Martian upper atmosphere |
| title_full_unstemmed | Observation of CO2++ dication in the dayside Martian upper atmosphere |
| title_short | Observation of CO2++ dication in the dayside Martian upper atmosphere |
| title_sort | observation of co2 dication in the dayside martian upper atmosphere |
| topic | maven martian ionosphere dication |
| url | http://www.eppcgs.org/article/doi/10.26464/epp2020036?pageType=en |
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