用地磁脉动日食效应探讨甚低纬Pc3-4地磁脉动源

SOURCE OF THE Pc3-4 GEOMAGNETIC PULSATION IN THE VERY-LOWER LATITUDE REGION STUDIED BY ECLIPSE EFFECTS OF GEOMAGNETIC PULSATION

在3次日食期间，利用甚低纬区和从低纬到甚低纬过渡区地面站进行的地磁脉动观测资料，分析了Pc3-4地磁脉动的南北分量（H）和东西分量（D）在H-D平面内矢端图主轴方向的变化．结果表明，当观测点纬度低于日全食带纬度时，H-D矢端图主轴有90°相移现象；当观测点纬度高于日全食带纬度时，则无这种现象．由此我们推测，甚低纬区和从低纬到甚低纬过渡区Pc3-4地磁脉动可能主要是过滤机制产生的．

The direction variations of the principal axis of the vector diagram in the H-D plane are analyzed by means of Pc3-4 geomagnetic pulsation data observed at ground stations in the very-lower latitude region and the transitional region between the verylower latitude and the low latitude during three solar eclipses. The results show that the direction of the principal axis of the vector diagram changed about 90 degrees when the latitude of observed station was lower than one of the total eclipse zone. While the direction of the principal axis of the vector diagram had not any variation when the latitude of observed station was higher than one of the total eclipse zone. From these results it is concluded that the Pc3-4 geomagnetic pulsation observed at ground stations in the very-lower latitude region and the transitional region between the very-lower latitude and the low latitude may mainly be responsible for the called filtering mechanism.