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| 1 | EUV-dependence of Venusian dayside ionopause altitude:VEX and PVO observations显示文摘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. | QianQian Han Markus Fraenz Yong Wei Eduard Dubinin Jun Cui LiHui Chai ZhaoJin Rong WeiXing Wan Yoshifumi Futaana | 2020 | Earth and Planetary Physics2020，4，1： | 1 |
| 2 | ENA detection in the dayside of Mars: ASPERA-3 NPD statistical study显示文摘 | A. Mura S. Orsini A. Milillo E. Kallio A. Galli S. Barabash P. Wurz A. Grigoriev Y. Futaana H. Andersson R. Lundin M. Yamauchi M. Fraenz N. Krupp J. Woch K. Asamura A.J. Coates C.C. Curtis K.C. Hsieh B.R. Sandel A. Fedorov M. Grande H. Koskinen J.U. Kozyr | 2008 | Planetary and Space Science2008，，6： | 1 |
| 3 | MAVEN observation of magnetosonic waves in the Martian magnetotail region显示文摘Magnetosonic waves are an important medium for energy transfer in collisionless space plasma.Magnetosonic waves have been widely investigated in the upstream of the bow shock at Mars.These waves are believed to originate from pickup ions or reflected particles.By utilizing MAVEN spacecraft data,we have observed the occurrence of quasi-perpendicularly propagating magnetosonic emissions near the proton gyrofrequency in the Martian magnetotail region.These plasma waves are associated with a significant enhancement of proton and oxygen flux.The excited magnetosonic waves could possibly heat the protons through resonance and facilitate the ionospheric plasma escape.Our results could be helpful to better understand the Mars’magnetospheric dynamics and offer insights into possible energy redistribution between waves and plasma in the Martian nightside magnetosphere. | ShangChun Teng JiCheng Sun JiaWei Gao Y.Harada Markus Fraenz DeSheng Han | 2024 | Earth and Planetary Physics2024，8，2： | 0 |
| 4 | Ablation of Venusian oxygen ions by unshocked solar wind显示文摘As an Earth-like planet Venus probably had a primordial dipole field for several million years after formation of the planet.Since this dipole field eventually vanished the ionosphere of Venus has been exposed to the solar wind.The solar wind is shocked near Venus,and then scavenges the ionospheric particles through the magnetosheath and the magnetotail.The escape rate of oxygen ions(O^+)estimated from spacecraft observations over the past several decades has manifested its importance for the evolution of planetary habitability,considering the accumulated effect over the history of Venus.However,all the previous observations were made in the shocked solar wind and/or inside the wake,though some simulations showed that unshocked solar wind can also ablate O^+ions.Here we report Venus Express observations of O^+ions in the unshocked solar wind during the solar minimum.The observations suggest that these O^+ions are accelerated by the unshocked solar wind through pickup processes.The estimated O^+escape rate,2.1×10^(24) ions/s,is comparable to those measured in the shocked solar wind and the wake.This escape rate could result in about 2 cm global water loss over 4.5 billion years.Our results suggest that the atmospheric loss at unmagnetized planets is significantly underestimated by previous observations,and thus we can emphasize the importance of an Earth-like dipole for planetary habitability. | Yong Wei Markus Fraenz Edward Dubinin Weixing Wan Tielong Zhang Zhaojin Rong Lihui Chai Jun Zhong Rixiang Zhu Yoshifumi Futaana Stas Barabash | 2017 | Science Bulletin2017，62，24： | 0 |
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