RESPONSE OF THE GEOMAGNETIC ACTIVITY INDEX KP TO THE INTERPLANETARY MAGNETIC FIELD.
CALIFORNIA UNIV BERKELEY SPACE SCIENCES LAB
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Interplanetary magnetic field observations with IMP-3 during eight solar rotations in the latter half of 1965 have been compared with the 3-hour Kp index. The results are consistent with those obtained with IMP-1 from three solar rotations in winter of 1963-4, indicating a stability in the response of geomagnetic activity during these years near solar activity minimum. The larger data sample in the present investigation reduces the probable error and delineates some interesting results. The average value of Kp decreases as the angle between the interplanetary field and the ecliptic changes from south to north. This is consistent with the reconnection of interplanetary and geomagnetic field lines as suggested by Dungey. As a function of interplanetary field magnitude B, the average value of the index ap is more linear than Kp, as might be expected. The relation can be described by ap 1.5 plus or minus 0.1 B 0.7 plus or minus 0.5. In the time interval covered by these observations the average value of Kp is consistently higher in sectors with interplanetary field directed away from the sun than in sectors with field directed toward the sun. Author
- Atmospheric Physics
- Unmanned Spacecraft