Pc5 geomagnetic fluctuations in response to solar wind excitation and their relationship with relativistic electron fluxes in the outer radiation belt

Abstract

This study is focused to investigate the Pc5 geomagnetic pulsations in response to the solar wind forcing and their relationship with the relativistic electron flux at geostationary orbit. We analyzed the correlation of the Pc5 power in the magnetosphere and on the ground, at low and high latitude, with the solar wind speed and fluctuation power of the interplanetary magnetic field and solar wind dynamic pressure through the years 2006 to 2010, also examining the relative timing between pulsations and solar wind parameters. We found a very significant correlation of the Pc5 power with simultaneous solar wind pressure fluctuations and with the solar wind speed lagged by several hours; the relative amplitude of the two correlation peaks depending on the solar cycle phase and on the latitude. We also found a strong relationship between the Pc5 power and the >600 keV and >2 MeV electron flux at geosynchronous orbit. Clear evidence emerges that the electron flux follows the Pc5 power by about 2 days; the time delay is a bit longer for the higher energy electrons.

ULF geomagnetic activity effects on tropospheric temperature, specific humidity, and cloud cover in Antarctica, during 2003–2010

“…An additional source of energy comes from the solar wind (SW). In particular, SW energy can be partially converted in magnetohydrodynamic ultralow frequency fluctuations (ULF, 1 mHz–5 Hz), which propagate inside the magnetosphere, and can lead to diffusion and precipitation of relativistic electrons (>100 keV) from the radiation belts [ Regi et al , ; Mann et al , ; Blum et al , ; Rodger et al , ], with potential effects on the atmospheric dynamics (see Mironova et al [] and Lam and Tinsley [] for a review).…”

Signatures of the ULF geomagnetic activity in the surface air temperature in Antarctica

“…Intense geomagnetic activity is characterized by the occurrence of ultralow frequency (ULF; ~1 mHz–10 Hz) fluctuations of the geomagnetic field lines, observed both in the magnetosphere and on the ground (see Menk [] for a review). In particular, lower‐frequency waves (Pc5 pulsations, ~1–7 mHz) are energized by the SW through several mechanisms, ranging from wave generation by Kelvin‐Helmholtz instability at the SW‐magnetosphere boundary to direct penetration into the magnetosphere of waves contained in the interaction regions at the leading edges of the SW high‐speed streams [ Regi et al ., ]. In recent years, Pc5 waves have received considerable attention regarding their role in accelerating to relativistic energy magnetospheric electrons, particularly in the outer radiation belt [ Baker et al ., ; Rostoker et al ., ; Mathie and Mann , ; Mann et al ., ].…”

Modulation of the ionosphere by Pc5 waves observed simultaneously by GPS/TEC and EISCAT

“…3, upper panel). The correlation threshold at 95 % confidence level, estimated by means a Monte Carlo test (Regi et al 2015), at this lag is ~0.2. Thus, the cross-correlation coefficient ~0.9 is statistically significant.…”