Effects of solar irradiance on the upper ionosphere and oxygen ion escape at Mars: MAVEN observations
Effects of solar irradiance on the upper ionosphere and oxygen ion escape at Mars: MAVEN observations
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DOI：
10.1002/2017ja024126
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发表时间：
2017-07
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通讯作者：
E. Dubinin;M. Fraenz;M. Pätzold;J. Mcfadden;P. Mahaffy;F. Eparvier;J. Halekas;J. Connerney;David A. Brain;B. Jakosky;Oleg L Vaisberg;Lev Zelenyi
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作者：
E. Dubinin;M. Fraenz;M. Pätzold;J. Mcfadden;P. Mahaffy;F. Eparvier;J. Halekas;J. Connerney;David A. Brain;B. Jakosky;Oleg L Vaisberg;Lev Zelenyi
我们基于2014年11月至2016年2月的火星大气与挥发物演化（MAVEN）数据，展示了太阳辐照度对火星上层电离层和逃逸通量影响的多仪器观测结果。结果表明，火星磁层内外能量大于30电子伏特的氧离子通量对极紫外（EUV）变化不敏感。相比之下，从上层电离层提取的低能离子通量随太阳辐照度增加而增加。这种增强与极紫外变化呈非线性关系，当极紫外（0.1 - 50纳米）辐射增加到≥0.1瓦/平方米时，增长了近1个数量级，这意味着低能成分的总离子损失增加到约1.8×10²⁵秒⁻¹。火星近尾区的冷离子流在与太阳风运动电场方向相反的方向上呈现出非常不对称的偏移。低能（能量≤30电子伏特）离子成分的通量对太阳风动压的变化也不敏感。
We present multi‐instrument observations of the effects of solar irradiance on the upper Martian ionosphere and escape fluxes based on the Mars Atmosphere and Volatile EvolutioN (MAVEN) data from November 2014 to February 2016. It is shown that fluxes of oxygen ions with E > 30 eV both inside and outside of the Martian magnetosphere are nonsensitive to EUV variations. In contrast, the fluxes of ions with lower energies extracted from the upper ionosphere increase with solar irradiance. Such an enhancement is nonlinear with the EUV variations and exhibits a growth by almost 1 order of magnitude when the EUV (0.1–50 nm) radiation increases to ≥0.1 W/m2 implying an enhancement of total ion losses of the low‐energy component to ∼1.8·1025 s−1. The flow of cold ions in the near‐Mars tail occurs very asymmetrical shifting in the direction opposite to the direction of the solar wind motional electric field. Fluxes of the low‐energy (E≤30 eV) ion component are also nonsensitive to the variations in solar wind dynamic pressure.