Hosokawa K, Miyoshi Y, Ozaki M, Oyama S-I, Ogawa Y, Kurita S, Kasahara Y, Kasaba Y, Yagitani S, Matsuda S, Tsuchiya F, Kumamoto A, Kataoka R, Shiokawa K, Raita T, Turunen E, Takashima T, Shinohara I, Fujii R
Graduate School of Informatics and Engineering, University of Electro-Communications, Chofu, Tokyo, Japan.
Center for Space Science and Radio Engineering, University of Electro-Communications, Chofu, Tokyo, Japan.
Sci Rep. 2020 Feb 25;10(1):3380. doi: 10.1038/s41598-020-59642-8.
The brightness of aurorae in Earth's polar region often beats with periods ranging from sub-second to a few tens of a second. Past observations showed that the beat of the aurora is composed of a superposition of two independent periodicities that co-exist hierarchically. However, the origin of such multiple time-scale beats in aurora remains poorly understood due to a lack of measurements with sufficiently high temporal resolution. By coordinating experiments using ultrafast auroral imagers deployed in the Arctic with the newly-launched magnetospheric satellite Arase, we succeeded in identifying an excellent agreement between the beats in aurorae and intensity modulations of natural electromagnetic waves in space called "chorus". In particular, sub-second scintillations of aurorae are precisely controlled by fine-scale chirping rhythms in chorus. The observation of this striking correlation demonstrates that resonant interaction between energetic electrons and chorus waves in magnetospheres orchestrates the complex behavior of aurora on Earth and other magnetized planets.
地球极地地区极光的亮度通常以从亚秒到几十秒不等的周期跳动。过去的观测表明，极光的跳动是由两个独立的周期性叠加而成，它们分层共存。然而，由于缺乏具有足够高时间分辨率的测量，极光中这种多时间尺度跳动的起源仍然知之甚少。通过协调在北极部署的超快极光成像仪与新发射的磁层卫星“曙光号”进行的实验，我们成功地确定了极光中的跳动与太空中被称为“合声”的自然电磁波强度调制之间的高度一致性。特别是，极光的亚秒级闪烁精确地由合声中的精细啁啾节奏控制。这种显著相关性的观测表明，磁层中高能电子与合声波之间的共振相互作用支配着地球和其他磁化行星上极光的复杂行为。
