EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations
The Venusian dayside ionosphere, similar to other planetary ionospheres, is produced primarily by ionization of its neutral upper atmosphere due to solar extreme ultraviolet (EUV) radiation. It has become clear that the expansion of the ionosphere may be strongly controlled by the EUV level, as exhi...
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| Format: | Article |
| Language: | English |
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Science Press
2020-01-01
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| Series: | Earth and Planetary Physics |
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| Online Access: | http://www.eppcgs.org/article/doi/10.26464/epp2020011?pageType=en |
| _version_ | 1811218714126712832 |
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| author | QianQian Han Markus Fraenz Yong Wei Eduard Dubinin Jun Cui LiHui Chai ZhaoJin Rong WeiXing Wan Yoshifumi Futaana |
| author_facet | QianQian Han Markus Fraenz Yong Wei Eduard Dubinin Jun Cui LiHui Chai ZhaoJin Rong WeiXing Wan Yoshifumi Futaana |
| author_sort | QianQian Han |
| collection | DOAJ |
| description | The Venusian dayside ionosphere, similar to other planetary ionospheres, is produced primarily by ionization of its neutral upper atmosphere due to solar extreme ultraviolet (EUV) radiation. It has become clear that the expansion of the ionosphere may be strongly controlled by the EUV level, as exhibited in data collected by the Pioneer Venus Orbiter (PVO) during one solar cycle (1978–1992). However, the EUV-dependence of the Venusian dayside ionopause altitude, which defines the outer boundary of the ionosphere, remains obscure because the PVO crossed the dayside ionopause only during the solar maximum; its periapsis lifted too high during the solar minimum. Recently, during the period 2006–2014, which included the longest and quietest solar minimum of the past several decades, Venus Express (VEX) provided measurements of the photoelectron boundary (PEB) over the northern high-latitude region. Since the photoelectron boundary is closely related to the ionopause, we have an opportunity to analyze the EUV effect on the dayside ionopause by combining PVO and VEX observations. We have evaluated and then reduced the orbit bias effect in data from both PVO and VEX, and then used the results to derive a relationship between solar EUV level and the dayside ionopause altitude. We find that the dayside ionopause altitude increases as the solar EUV level increases, which is consistent with theoretical expectations. |
| first_indexed | 2024-04-12T07:14:03Z |
| format | Article |
| id | doaj.art-897fac6111504167bc3f150e54f1338f |
| institution | Directory Open Access Journal |
| issn | 2096-3955 |
| language | English |
| last_indexed | 2024-04-12T07:14:03Z |
| publishDate | 2020-01-01 |
| publisher | Science Press |
| record_format | Article |
| series | Earth and Planetary Physics |
| spelling | doaj.art-897fac6111504167bc3f150e54f1338f2022-12-22T03:42:33ZengScience PressEarth and Planetary Physics2096-39552020-01-0141738110.26464/epp2020011hanqianqian-01EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observationsQianQian Han0Markus Fraenz1Yong Wei2Eduard Dubinin3Jun Cui4LiHui Chai5ZhaoJin Rong6WeiXing Wan7Yoshifumi Futaana8Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaMax-Planck-Institute for Solar System Research, Goettingen, DE 37077, GermanyKey Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaMax-Planck-Institute for Solar System Research, Goettingen, DE 37077, GermanySchool of Atmospheric Sciences, Sun Yat-Sen University, Zhuhai Guangdong 519082, ChinaKey Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaKey Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaKey Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaSwedish Institute of Space Physics, Kiruna, SE 98128, SwedenThe Venusian dayside ionosphere, similar to other planetary ionospheres, is produced primarily by ionization of its neutral upper atmosphere due to solar extreme ultraviolet (EUV) radiation. It has become clear that the expansion of the ionosphere may be strongly controlled by the EUV level, as exhibited in data collected by the Pioneer Venus Orbiter (PVO) during one solar cycle (1978–1992). However, the EUV-dependence of the Venusian dayside ionopause altitude, which defines the outer boundary of the ionosphere, remains obscure because the PVO crossed the dayside ionopause only during the solar maximum; its periapsis lifted too high during the solar minimum. Recently, during the period 2006–2014, which included the longest and quietest solar minimum of the past several decades, Venus Express (VEX) provided measurements of the photoelectron boundary (PEB) over the northern high-latitude region. Since the photoelectron boundary is closely related to the ionopause, we have an opportunity to analyze the EUV effect on the dayside ionopause by combining PVO and VEX observations. We have evaluated and then reduced the orbit bias effect in data from both PVO and VEX, and then used the results to derive a relationship between solar EUV level and the dayside ionopause altitude. We find that the dayside ionopause altitude increases as the solar EUV level increases, which is consistent with theoretical expectations.http://www.eppcgs.org/article/doi/10.26464/epp2020011?pageType=envenusionopauseionospheresolar activity |
| spellingShingle | QianQian Han Markus Fraenz Yong Wei Eduard Dubinin Jun Cui LiHui Chai ZhaoJin Rong WeiXing Wan Yoshifumi Futaana EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations Earth and Planetary Physics venus ionopause ionosphere solar activity |
| title | EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations |
| title_full | EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations |
| title_fullStr | EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations |
| title_full_unstemmed | EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations |
| title_short | EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations |
| title_sort | euv dependence of venusian dayside ionopause altitude vex and pvo observations |
| topic | venus ionopause ionosphere solar activity |
| url | http://www.eppcgs.org/article/doi/10.26464/epp2020011?pageType=en |
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