近日，武汉大学汪晖团队研究了电离层电磁离子回旋波的半球不对称性及其与南大西洋异常的关系。2026年2月9日，《中国科学：地球科学》杂志发表了这一成果。

研究组基于2015年至2018年Swarm卫星观测数据，对电离层电磁离子回旋波（EMIC）进行了分析，重点关注其半球不对称性及南大西洋异常区（SAA）的调制作用。与相同纬度其他区域相比，SAA区域内EMIC波的功率谱密度（PSD）和发生率均显著增强。在SAA区域观测到的波通常频率较低，且源自略高L壳层位置。He频段波的PSD半球差异更显著，而O频段波则在频率和发生率上表现出更大差异。

在00-12地方时期间，南半球的PSD和发生率均高于北半球，这一现象在春秋分附近尤为明显。虽然SAA区域的PSD和发生率增强在地磁平静期更为突出，但频率与L壳层的半球差异在地磁扰动条件下更为显著。EMIC波的发生率随太阳风动压增强而增加；PSD不对称性在低动压区间更显著，而频率差异在高动压区间更为明显。这些发现深化了研究组对EMIC波半球不对称性及其受SAA调制机制的理解。

附：英文原文

Title: Hemispheric asymmetry of ionospheric electromagnetic ion cyclotron waves and the association with the South Atlantic Anomaly

Author: Hui WANG, Hermann LüHR, Chengzhi WANG

Issue&Volume: 2026/02/09

Abstract: This study investigates ionospheric electromagnetic ion cyclotron (EMIC) waves on the basis of Swarm satellite observations from 2015 to 2018, focusing on hemispheric asymmetries and their modulation by the South Atlantic Anomaly (SAA). Both the power spectral density (PSD) and occurrence rate of EMIC waves are significantly enhanced in the SAA relative to other regions at similar latitudes. Waves observed in the SAA region generally exhibit lower frequencies and originate from slightly higher L shells than their northern counterparts. He-band waves show stronger hemispheric contrasts in PSD, while O-band waves display larger differences in frequencies and occurrence rates. The Southern Hemisphere shows higher PSD and occurrence rates than the Northern Hemisphere during 00–12 local time, which becomes particularly pronounced near equinoxes. Although PSD and occurrence rate enhancements in the SAA region are more prominent during geomagnetically quiet periods, hemispheric differences in frequency and L shell intensify under disturbed conditions. EMIC wave occurrence also increases with solar wind dynamic pressure; PSD asymmetry is greater during low-pressure intervals, whereas frequency differences become more pronounced during high-pressure intervals. These findings deepen our understanding of the hemispheric asymmetry of EMIC waves and the mechanisms by which they are modulated by the SAA.

DOI: 10.1007/s11430-025-1793-9

Source: https://www.sciengine.com/SCES/doi/10.1007/s11430-025-1793-9