Effects of the strength of the geomagnetic main field strength on the dynamo action in the ionosphere
Effects of the strength of the geomagnetic main field strength on the dynamo action in the ionosphere
复制标题
地磁主场强弱对电离层发电机作用的影响
DOI：
10.1029/95ja03807
复制
发表时间：
1996
影响因子：
--
通讯作者：
M. Takeda
中科院分区：
文献类型：
--
作者：
M. Takeda
研究了地磁主场强度对电离层电动力学的影响。在三倍主场强、正常场强和1/10场强的情况下，估算了电离层的电导率。结果表明，当场强降低时，Pedersen电导率最大值的高度上移，高度积分的Pedersen和Hall电导率增强。对上述三种情况下电离层发电机的电位差和电流进行了模拟。地磁主场的减弱使感应场变小，从而使电位差减小。然而，由于发电机区域被抬升，有效中性风速变大，因此减小的幅度没有主磁场的大。相反，高度积分的电离层电流增强，因为电流强度基本上是由发电机区域的电子密度和中性风速的乘积决定的。较低的回旋频率的电子和离子，由于弱的主场移动发电机区向上的高度，电子密度和风速较大。
Effects of the strength of the geomagnetic main field on the electrodynamics of the ionosphere were studied. Electric conductivities of the ionosphere were estimated for the cases of three times, normal, and 1/10 strength of the main field. It was shown that when the field strength decreases, altitudes of Pedersen conductivity maxima shift upward, and height-integrated Pedersen and Hall conductivities are enhanced. The electric potential difference and currents of the ionospheric dynamo were also simulated for the above three cases. Weakening of the geomagnetic main field decreases the potential difference because of the smaller induction field. However, the reduction is not as large as that of the main field because the dynamo region is lifted and effective neutral wind velocity becomes large. On the contrary, height-integrated ionospheric currents are enhanced because the current intensity is essentially determined by the product of the electron density and the neutral wind velocity in the dynamo region. Lower gyrofrequencies of electrons and ions due to the weak main field shift the dynamo region upward to the altitudes where the electron density and the wind velocity are larger.