High-latitude Pc1–2 geomagnetic pulsations and their connection with location of the dayside polar cusp

Statistical study of Pc1-2 wave propagation characteristics in the high-latitude ionospheric waveguide

“…Stations located in the auroral zone (63° and 64°) also show two maxima but at significantly different times: a peak at 16:00–17:00 MLT and a secondary peak in the early morning sector. Bolshakova et al [1980] suggested the existence of the two occurrence peaks is attributed to the position of the stations with respect to the dayside polar cusp since the stations approach the cusp twice in the course of their diurnal rotation. The MLT occurrences observed by Plyasova‐Bakounina et al [1996] using a ground network of six stations at latitudes 65° to 76° appear to be similar to those in the Bolshakova et al [1980] study.…”

“…Ground observations [e.g., Bolshakova et al , 1980; Menk et al , 1992; Neudegg et al , 1995] suggested the dayside cusp as the magnetospheric source regions of Pc1–2 wave activity. Fraser [1975a] estimated the general location of the injection region near the dawn terminator in the range 58°–66° ILAT ( L = 3.5–6) using the polarization ellipse major axis azimuthal directions and direction of arrival triangulation method.…”

“…They also found a secondary peak in the dawn sector (03:00 to 09:00 MLT) at L > 7. Bolshakova et al [1980] used 7 ground magnetometers to suggest that occurrence depends significantly on geomagnetic latitude. According to their study, one maximum has been found around noon from two stations at higher latitudes (77° and 85°).…”

Geomagnetic pulsations in the polar cap.

“…The theoretical estimates of the periods and amplitudes in the transition region (A<lOr, TN2-5sec) and on the ground (AN300-500mr) have the same order of magnitude as the experimentally obtained values in space and on the ground. The suggested mechanism explains the localization, quasipermanence and the absence of conjugacy for these pulsations (BoLSHAKOVA et al, 1980). The main properties of Pc 1-2 are given in the Table 1.…”

“…After some time dt, particles with greater velocities will be concentrated on the front of the beam, and particles with lower velocities on the tail (i. e. Vifr>Vitaii). The main bulk of the particles will be located in the middle of the beam (BOLSHAKOVA et al, 1980). On the front of such beams oscillations with smaller periods will be amplified, and on the tails, oscillations with greater periods.…”