基于GNSS观测的全球赤道等离子体泡对太阳和地磁活动及季节依赖特征

赤道等离子体泡是在磁赤道和低纬地区一种通常发生在夜间的大尺度电离层不规则结构.本文利用2010—2021年全球低纬地区GNSS TEC监测仪长期观测数据,分析了赤道等离子体泡对太阳和地磁活动及季节的依赖特征.结果表明,全球每个经度区赤道等离子体泡发生率与太阳活动都显著正相关,赤道等离子体泡的日发生率与F₁₀₇指数相关系数接近0.70.经度-60°~-30°在赤道等离子体泡高发月份的日落后发生率与F₁₀₇的相关关系有明显的饱和效应.在季节变化方面,经度-60°~-30°赤道等离子体泡主要发生在1—3月和10—12月,其他经度主要发生在分季.不同经度区赤道等离子体泡日落后发生率季节不对称性存在显著区别,在太阳活动上升期,经度-60°~-30°的10—12月发生率明显高于1—3月;在太阳活动下降期,0°~180°经度区3月分季高于9月分季.此外,地磁扰动对产生赤道等离子体泡主要是抑制作用,特别是在太阳活动高年、分季.

Solar and geomagnetic activity and seasonal dependence of global equatorial plasma bubbles based on GNSS observations

Equatorial plasma bubbles (EPBs) are large-scale ionospheric irregularities that typically occur at night over the magnetic equator and low latitudes. In this paper, the long-term GNSS observation data of the low-latitude regions from 2010 to 2021 are used to analyze the solar and geomagnetic activity and seasonal dependence of EPBs. The results show that the occurrence rate of EPBs in every longitude region is significantly positively correlated with solar activity, and the correlation coefficient between the daily occurrence rate of EPBs and the F107 index is close to 0.70. In the range of longitude from -60° to -30°, the correlation between the occurrence rate of post sunset EPBs and F107 has obvious saturation effect during high-occurrence months. The EPBs mainly occur in January—March and October—December of longitude from -60° to -30°, and typically occur in equinoxes over other longitudes. The seasonal asymmetry of the occurrence rate of post sunset EPBs in different longitude regions is significantly different. During the increasing phase of solar activity, the occurrence rate of EPBs in longitude -60°~-30° from October to December is much higher than that from January to March. During the decreasing phase of solar activity, the occurrence rate of EPBs in longitude 0°~180° is higher in March equinox than that in September equinox. Additionally, geomagnetic disturbances mainly suppress the EPBs, especially in the high solar activity years and equinox seasons.