An investigation of the influence of data and model inputs on assimilative mapping of ionospheric electrodynamics
An investigation of the influence of data and model inputs on assimilative mapping of ionospheric electrodynamics
复制标题
数据和模型输入对电离层电动力学同化绘图影响的研究
DOI：
10.1029/2000ja000606
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发表时间：
2001
影响因子：
--
通讯作者：
D. Evans
中科院分区：
文献类型：
--
作者：
G. Lu;A. Richmond;J. Ruohoniemi;R. Greenwald;M. Hairston;F. Rich;D. Evans
1996年11月24日的地球空间环境模拟（GEM）亚暴挑战事件，已被用作一个测试案例，调查不同的数据和模型输入的同化映射的电离层电动力学（AMIE）输出的影响。在此期间，行星际磁场（IMF）由北向南，然后返回到北。当天晚些时候，系统产生了强度约为600 nT的中度亚风暴。从超级双极光雷达网（SuperDARN）的数据得出的AMIE对流模式一般是类似于那些单独使用地面磁力计，特别是在相对稳定的向南IMF期间。然而，在向北的IMF期间和在亚暴期间发现了一些差异，即，在当地中午附近由SuperDARN成像的反向对流配置是缺席的磁强计观测，而在亚暴扩展阶段由磁强计记录的夜侧强对流是没有看到的雷达。不同的电导模型似乎没有大的影响电离层对流和焦耳加热的大尺度分布，但它们确实改变了跨极冠电位降和半球综合焦耳加热率的近2倍。当AMIE导出的电位降与现场测量沿着卫星轨道进行比较时，发现AMIE低估了20 kV的电位降，低估了22%。对基于SuperDARN和地面磁力计数据的AMIE结果的分析再次表明，电离层对流对IMF突然南转的反应是全球性的，几乎是同时发生的。
The Geospace Environment Modeling (GEM) substorm challenge event of November 24, 1996, has been used as a test case to investigate the influence of different data and model inputs on the assimilative mapping of ionospheric electrodynamics (AMIE) outputs. During that period the interplanetary magnetic field (IMF) went from northward to southward and then returned to northward. In the later part of the day a moderate substorm with AL ∼ -600 nT took place. The AMIE convection patterns derived from the Super Dual Auroral Radar Network (SuperDARN) data alone are generally similar to those derived using ground magnetometer alone, especially during the relatively stable southward IMF period. However, some differences are found during the northward IMF period and during the substorm; namely, the reversed convection configuration near local noon imaged by SuperDARN is absent in the magnetometer observations while the strong convection on the nightside recorded by the magnetometers during the substorm expansion phase is not seen by the radars. Different conductance models do not seem to have a big effect on the large-scale distributions of ionospheric convection and Joule heating, but they do alter the cross polar cap potential drop and the hemispheric integrated Joule heating rate by nearly a factor of 2. When the AMIE-derived electric potential drop was compared with the in situ measurements along the satellite track, it is found that AMIE underestimated the potential drop by 20 kV, amounting to a 22% underestimation. The analysis of the AMIE results based on the SuperDARN and ground magnetometer data reiterates the view that the response of ionospheric convection to a sudden IMF southward turning is global and nearly simultaneous.