An initial response of magnetic ®elds at geosynchronous orbit to Pi 2 onset as observed from the dip-equator
نویسندگان
چکیده
Fluxgate magnetometer data recorded at the dip-equator (Huancayo, Peru; 1.44°N, 355.9° in geomagnetic coordinates; 12.1°S, 75.2°W in geographic coordinates; L = 1.00) with higher accuracy of timing (0.1 s) and amplitude resolution (0.01 nT) were utilized to survey an onset of Pi 2 pulsations in the midnight sector (2100±0100 LT) during PROMIS (Polar Region and Outer Magnetosphere International Study) periods (1 March±20 June, 1986). It is found that changing ®eld line magnitude and vector as observed by magnetometer on board the synchronous satellites in the midnight sector often takes place simultaneously with the onset of Pi 2 pulsations at the dip-equator. The ®eld disturbances that follow thereafter tend to last for some time both at the geosynchronous altitudes and the dip-equator. In this report, we examine the initial response of the ®eld lines in space, and attempt to classify how the ®eld line vector changed in the meridional plane.
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