Average high latitude magnetic field data from northern observatories are examined for three ranges of magnetic disturbance level, K p = 1-to 1+, 2- to 3+, and > 4-. Except for 0-8h W LT, 55-78° invariant latitude, during away interplanetary magnetic field sectors, the variations between season and sector have the same characteristics at all Kp ranges. Because the amplitude of sector differences is much larger at sunlit local times than in the midnight sector, it is concluded that the current system of Svalbard (1973) is not adequate to describe the sector variations in magnetic disturbance, other current systems are discussed briefly. The disturbance morphology and seasonal variation at all Kp levels confirms the results of previous studies which indicate that latitudinally broad current systems, like Sp q , and non-ionospheric sources are present in addition to latitudinally narrow electrojet cur rents. Comparison of data between K p levels indicates that the Harang discontinuity shifts toward earlier MLT with increasing K p level.
展开▼
