Pc5 pulsations on the ground, in the magnetosphere, and in the electron precipitation: Event of 19 January 2005

Abstract

[1] In the first part of our paper, we consider the pattern of geomagnetic pulsations in the Pc5 range in the North European area, based on an event of 19 January 2005. Intense pulsations, observed in Lovozero at Kola Peninsula, were accompanied by auroras north of the station, recorded by an all-sky TV camera. In the second part, we consider the global pattern of amplitudes and phases of geomagnetic pulsations for this event, which includes data from nearly conjugate stations and the magnetic data of GOES 10 and 12, confirming the quasi-stationary model for magnetic field distribution on the ground. In the event, the auroral luminosity oscillated with the same 5 min period as the magnetic field. Magnetic data from Scandinavia and data from North Europe riometers show analogous pulsations. The maximal intensity of geomagnetic pulsations in this region occurred near the pulsating aurora, but there was a reversal of pulsation polarity in the X-component. In the area of phase change the value of the Z-component is maximal. We suggest that geomagnetic pulsating variations, observed on the surface, are determined by Biot-Savart's law for a three-dimensional current system, the extra-ionospheric part of which is spatially coincident with auroral electron flux. The electric field in the ionosphere is found from the current continuity condition and the value of Pedersen conductivity. The directions to the pulsating current, calculated by using the magnetic data from Lovozero, are close to the directions of the auroral area. We also claim that this approach is applicable to all short periodic oscillations observed on the surface. Satellite data indicates the same periods, but with oscillations that appear to be poloidal on GOES10 and toroidal on GOES12, suggesting the traveling character of the wave.

Non-triggered auroral substorms and long-period (1–4 mHz) geomagnetic and auroral luminosity pulsations in the polar cap

“…Although there are numerous papers describing aurora modulation by Pc5 pulsations (see, e.g., Xu et al, 1993;Safargaleev et al, 2005;Roldugin and Roldugin, 2008), amplitudes of geomagnetic and auroral luminosity pulsations are controlled by different physical factors. Thus, geomagnetic ULF power at high latitudes is essentially controlled by SW or IMF parameters, while the fluctuations of auroral luminosity are more local and their amplitudes depend on the energy distribution of particles at a particular L shell.…”

Pc1–2 auroral pulsations

“…[26] Though the above estimates are rough, the cases presented in Figures 1, 5, 6, and also in Figure 7 for image blown up indicate the absence of any time lag within accuracy of 1 s. This infers that the Pc1-2 pulsations observed on the ground are more likely connected with the magnetic fields of the currents carried by auroral particles than with wave packets, as it is presumed for Pi1-2 and for Pc4-5 in Roldugin et al [1971] and Roldugin and Roldugin [2008].…”

“…Raspopov and reported an event of intense regular geomagnetic Pc4 pulsations with the period of 70 s at Loparskaya observatory (corrected geomagnetic latitude Φ = 64.3 ), which were accompanied by similar regular luminosity fluctuations at dawn. Roldugin and Roldugin [2008] described an event of regular auroral intensifications with 5 min period observed in the all-sky camera films, which were accompanied by intense (up to 200 nT) Pc5 geomagnetic pulsations in the Scandinavian sector about 0900 magnetic local time (MLT). Roldugin and Roldugin [2010] studied 12 events of Pc4-5 pulsations recorded during photometric observations within the 2007-2008 polar night season in Spitsbergen, and in all events, similar auroral fluctuations were present.…”

“…There is no generally accepted theory to explain particle precipitation during ULF wave activity. In Roldugin et al [1971] and Roldugin and Roldugin [2008] the problem of pulsation generation is treated in a different way. Namely, it is stated that the pulsations recorded on the ground are related to the current systems, the extra-ionospheric part of which is a pulsating flux of charged auroral particles.…”

Influence of anomalous particle diffusion on the current system formation and coherence of Pi2 geomagnetic pulsation local ionospheric sources

“…It is necessary to determine whether it is possible to uniformly describe the dynamics of different sources in the Pi2 generation region. Together with pulsed activations of stationary sources (Roldugin and Roldugin, 2008), one can con sider random on-off switching of chaotically located nonstationary sources. If not, they can be interpreted as mobile formations.…”