ULF-Waves on the Ground and in Space - Hydromagnetic Waves in the Magnetosphere and the Ionosphere - page 52

Fig. 3.3. Latitudinal variations of the Fourier amplitudes and phases of the NS
ULF-magnetic component along the CANOPUS Churchill line. After [42]

Amplitude distributions of individual cases of Pc 5 are strongly elongated
along the parallel ( δλ =60 ◦ ) and bounded in latitude [81]. At distance of
δϕ 1 ◦ , a sharp change can occur in the pulsation period. The latitude of

the Pc 5 intensity maximum decreases with as the Kp -index increases, and
the main period falls from 500 to 300 s when the maximum is shifted from
the latitude of ϕ ◦ ≈

≈

60 ◦ . Such a connection of the period with
geomagnetic latitude indicates that Pc 5 pulsations emerge on field-lines ever
closer to Earth as magnetospheric perturbation increases.
Figure 3.4 shows the direction of horizontal magnetic vector rotation con-
structed on data from a Canadian station network [77]. A change of the
rotation sign is clearly visible during transition from morning to evening
oscillations.
A comparison of records of such pulsations made by a satellite and two
stations at approximately footprint points showed that they are clearly visible
both on the ground and in space ([26], [47], [87]). Usually, variations of the H -
component (North-South) at the conjugate points occur in phase, while those
of the D -component (East-West) occur in antiphase ([5], [54]). The horizontal
vector rotates in opposite directions in two hemispheres. Figure 3.5 presents
simultaneous magnetograms from two observatories: Byrd (Antarctic) and
Pole (Arctic)[34] . It can be seen that separate Pc 5 splashes have a kind of
corresponding trigger pulses at the start of a pulsation train.

70 ◦ to ϕ ◦ ≈