Coupling of perturbations in the solar wind density to global Pi3 pulsations: A case study
Coupling of perturbations in the solar wind density to global Pi3 pulsations: A case study
复制标题
DOI：
10.1029/2006ja011675
复制
发表时间：
2007-05
影响因子：
--
通讯作者：
Desheng Han;Huigen Yang;Z.-T. Chen;T. Araki;M. Dunlop;M. Nosé;T. Iyemori;Qiang Li;Yu-fen Gao;K. Yumoto
中科院分区：
文献类型：
--
作者：
Desheng Han;Huigen Yang;Z.-T. Chen;T. Araki;M. Dunlop;M. Nosé;T. Iyemori;Qiang Li;Yu-fen Gao;K. Yumoto
[1]通过来自多个卫星和地面站的磁场测量，研究了典型的PI3脉动。低纬大跨度地面观测表明，PI3脉动的幅度在白天达到峰值，向夜间逐渐减小。这种影响以及白天的波位相先于黑夜的波位相的事实，意味着PI3的来源在白天。GEOTAIL卫星(就在磁层外)观测到的太阳风动压变化与地面磁场变化高度相关。在这种情况下，我们认为全球PI3脉动是由太阳风动压的脉冲变化直接驱动的。0930LT时沿纬向磁力计磁链观测到的PI3脉动显示出明显的赤道增强，1630LT时沿纬度链观测到的PI3脉动的位相滞后于低纬度。低空极地轨道卫星Oersted也在日侧内部磁层观察到了这种脉动。Oersted的B∥(向北)分量与航天器路径下方倾角赤道上观测到的X分量完全不同，这表明倾角赤道上的PI3脉动是由电离层电流的振荡引起的。我们认为不同纬度的PI3脉动是由不同的机制产生的。
[1] A typical Pi3 pulsation is examined by magnetic field measurements from multiple satellites and ground stations. Low-latitude ground observations with a wide longitudinal span indicate that the amplitude of the Pi3 pulsation peaks on the dayside and is gradually decreasing toward the nightside. This effect and the fact that the wave phase on the dayside leads that on the nightside, imply that the source of the Pi3 lies on the dayside. Variations in solar wind dynamic pressure observed by the GEOTAIL satellite (just outside of the magnetosphere) are highly correlated with these ground magnetic field variations. We argue in this case that the global Pi3 pulsation is directly driven by impulsive variations in the solar wind dynamic pressure. The Pi3 pulsation observed along the latitudinal magnetometer chain at 0930LT shows significant equatorial enhancement and additional observations along a latitudinal chain at 1630LT show that the phase of the Pi3 pulsation at high latitudes lags behind that at low latitudes. The low-altitude polar orbiting satellite Oersted also observed this pulsation in the dayside inner magnetosphere. The B∥ (northward) component at Oersted is strictly out of phase with the X component observed at the dip equator below the spacecraft path, which indicates that the Pi3 pulsation at the dip equator is caused by oscillation of an ionospheric current. We propose that the Pi3 pulsations at different latitudes are generated by different mechanisms.