THE IONOSPHERIC DISTURBANCE DYNAMO
THE IONOSPHERIC DISTURBANCE DYNAMO
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DOI：
10.1029/ja085ia04p01669
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发表时间：
1980-01-01
影响因子：
2.8
通讯作者：
RICHMOND, AD
中科院分区：
文献类型：
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作者：
BLANC, M;RICHMOND, AD
对磁暴期间极光加热产生的热层风及其全球发电机效应进行了数值模拟研究，确定了电离层扰动发电机的主要特征。在极光加热的驱动下，哈德利环流在中纬度约120公里以上的赤道风中形成。这些风对角动量的输送导致中纬度热层的副旋转或相对于地球的向西运动。向西的风又驱动向赤道的佩德森电流，佩德森电流向赤道聚集电荷，导致产生向极的电场、向西的E × B漂移和向东的电流。当模拟真实的当地时间电导率变化时，发现向东的中纬度电流通过低纬度部分关闭，导致“反Sq”型电流涡旋。因此，低纬度地区的电场和电流都与它们正常的安静日行为相反。扰动风、电场和电流的总模式叠加在背景静日模式上。当中性风被人为地限制在夜侧时，主要向西的E × B等离子体漂移的基本模式仍然在夜侧占主导地位，但不再延伸到昼侧。大量的观测证据表明，电离层扰动发电机对中低纬度地区的暴时电离层电场有明显的影响。
A numerical simulation study of the thermospheric winds produced by auroral heating during magnetic storms, and of their global dynamo effects, establishes the main features of the ionospheric disturbance dynamo. Driven by auroral heating, a Hadley cell is created with equatorward winds blowing above about 120 km at mid‐latitudes. The transport of angular momentum by these winds produces a subrotation of the mid‐latitude thermosphere or westward motion with respect to the earth. The westward winds in turn drive equatorward Pedersen currents which accumulate charge toward the equator, resulting in the generation of a poleward electric field, a westward E × B drift, and an eastward current. When realistic local time conductivity variations are simulated, the eastward mid‐latitude current is found to close partly via lower latitudes, resulting in an ‘anti‐Sq’ type of current vortex. Both electric field and current at low latitudes thus vary in opposition to their normal quiet‐day behavior. This total pattern of disturbance winds, electric fields, and currents is superimposed upon the background quiet‐day pattern. When the neutral winds are artificially confined on the nightside, the basic pattern of predominantly westward E × B plasma drifts still prevails on the nightside but no longer extends into the dayside. Considerable observational evidence exists, suggesting that the ionospheric disturbance dynamo has an appreciable influence on storm‐time ionospheric electric fields at middle and low latitudes.