Relation between the short-term variation of the Jovian radiation belt and thermosphere derived from radio and infrared observations
Relation between the short-term variation of the Jovian radiation belt and thermosphere derived from radio and infrared observations
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射电和红外观测得出的木星辐射带与热层短期变化的关系
DOI：
10.1002/2015ja021374
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
and A. Morioka
中科院分区：
文献类型：
--
作者：
Kita,H.;H. Misawa;A. Bhardwaj;F. Tsuchiya;T. Sakanoi;Y. Kasaba;C. Tao;Y. Miyoshi;and A. Morioka
我们报道了首次对木星热层的木星同步辐射(JSR)和H~(3+)辐射的综合观测，以研究木星辐射带中短期(天到周)变化的产生过程。这些观测是由巨型米波射电望远镜和美国宇航局红外望远镜设施在2011年11月进行的。从11月6-9日到11月12-17日，JSR的总通量密度增加了约5%，这与太阳UV/EUV通量的增加有关。从11月7日到14日，在中纬度地区观测到可能的红外H~(3+)发射增加，对应的温度变化约为10 K。这些结果与太阳UV/EUV加热引起热层温度和JSR变化的情况相一致。沿赤道地区的射电图像显示，JSR强度在1.5木星半径(RJ)内减弱，峰值位置向外移动。这意味着，尽管径向扩散同时增加，高能电子仍被一些内部损耗过程衰减。辐射带的物理模型表明，这种内部损失过程可以解释观测到的亮度分布的变化。典型的损失时间尺度大于强扩散极限，表明存在波粒相互作用等俯仰角扩散过程。因此，JSR总通量密度和热层温度的变化似乎与情景一致，JSR的亮度分布可以用伴随着内部损失过程的径向扩散的增加来解释。
We report the first comprehensive observations of Jovian synchrotron radiation (JSR) and H3+emission from the Jovian thermosphere to investigate the generation process of short‐term (days to weeks) variations in the Jovian radiation belt. The observations were made by the Giant Metrewave Radio Telescope and NASA Infrared Telescope Facility during November 2011. The total flux density of JSR increased by approximately 5% between 6–9 November and 12–17 November, associated with the increased solar UV/EUV flux. From 7 to 14 November, a possible rise in the infrared H3+emission was observed in the middle‐latitude region, corresponding to a temperature variation of approximately 10 K. These results are consistent with the scenario that the solar UV/EUV heating causes variations in the thermospheric temperature and JSR. Radio images along the equatorial region showed that the JSR intensity decreased inside 1.5 Jovian radii (RJ) and the peak position shifted outward. This implies that energetic electrons are attenuated by some internal loss process, despite the simultaneous increase in radial diffusion. A physical model for the radiation belt shows that such an internal loss process can explain the observed variation of brightness distribution. Typical loss time scale is longer than strong diffusion limit, which suggests the existence of some pitch angle diffusion process such as wave‐particle interaction. Thus, variations of the total JSR flux density and thermospheric temperature seem consistent with the scenario, and the brightness distribution of JSR can be explained by the increase in radial diffusion accompanied by internal loss processes.