Radiation belt electron acceleration by ULF wave drift resonance: Simulation of 1997 and 1998 storms
Radiation belt electron acceleration by ULF wave drift resonance: Simulation of 1997 and 1998 storms
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ULF波漂移共振辐射带电子加速：1997年和1998年风暴的模拟
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
M. Lessard
中科院分区：
文献类型：
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作者：
M. Hudson;S. Elkington;J. Lyon;M. Wiltberger;M. Lessard
Pc 5超低频波被认为是同时与CME磁云事件相关的辐射带通量的上升。用L1测量的太阳风参数驱动的三维全球MHD程序模拟了1997年和1998年、1997年1月10-11日和5月1-4 -15日、1998年5月1-4日和8月26-28日的四个磁暴期。场输出已被用于推进电子导引中心在赤道平面内的轨迹。对超低频波的模式结构进行了时间序列分析。环形场线谐振与低方位角模式数和频率相称的电子漂移周期被确定在径向电场分量，沿着与增强的功率在极向（方位角）电场分量。从地球同步轨道到L=3-4，在几百keV至MeV能量范围内电子向内径向传输的模拟时间尺度随超低频波功率和输入磁层的总能量的水平而变化。在研究的四个事件中，1998年5月的风暴期是最具地球效应的，1997年1月最不具地球效应的，就模拟的电子径向传输和辐射而言。这种传输速率与模拟中激发的ULF波的水平以及所提出的漂移共振加速机制一致。
Pc 5 ULF waves are seen concurrently with the rise in radiation belt fluxes associated with CME-magnetic cloud events. Four such geomagnetic storm periods in 1997 and 1998, 10-11 January and 14-15 May, 1997; 1-4 May and 26-28 August, 1998, have been simulated with a 3D global MHD code driven by L1-measured solar wind parameters. The field output has been used to advance electron guiding center trajectories in the equatorial plane. The time series has also been analyzed for ULF wave mode structure. Toroidal field line resonances with low azimuthal mode number and frequencies commensurate with the electron drift period are identified in the radial electric field component, along with enhanced power in the poloidal (azimuthal) electric field component. The simulated time scale for inward radial transport of electrons in the several hundred keV to MeV energy range, from geosynchronous orbit to L=3-4, varies with the level of ULF wave power and overall energy input to the magnetosphere. Of the four events studied, the May 1998 storm period was most geoeffective and the January 1997 least so, in terms of simulated radial transport and energization of electrons. This transport rate is consistent with the level of ULF waves excited in the simulations, and the proposed drift resonant acceleration mechanism.