Time-spatial correspondence between Pi2 wave power and ultra-violet aurora bursts

Abstract

We have examined snapshots of overlaid ultra-violet (UV) auroral images from POLAR and IMAGE spacecraft and ULF wave power in the Pi2 frequency band (5-30 mHz). The latitudinal distribution of the Pi2 spectral power, as well as the position of the ionospheric electrojet, are inferred from the MACCS-CARISMA-MEASURE array of magnetic stations. A substorm develops as a series of "detonations", accompanied by an enhancement of auroral luminosity, intensification of the ionospheric currents, and a burst of Pi2 wave power. The epicenter of each detonation leaps during each activation poleward and westward. The latitudinal location of the auroral ionospheric westward electrojet and Pi2 power is found to be mainly associated with the poleward border of the auroral activation region. The result of case studies is supported by statistical superposed latitudinal distributions of the auroral intensity and Pi2 power. The found correspondence between the UV auroral oval and Pi2 power "epicenter" may help to identify a possible channel of Pi2 wave energy transmission from the magnetotail to the ground. KEYWORDS: ULF waves; Pi2 pulsations; substorm; auroral oval; ionospheric electrojet.

Conjugate properties of Pi3/Ps6 pulsations according to Antarctica-Greenland observations

“…The subtraction of the filtered variations from raw data provides detrended time series of Pi3 pulsations. The Bedenko et al, 2017]. Thus, upon data processing we have produced the following plots: stacked raw magnetograms of all 3 components; detrended magnetograms X d (t) which show ULF pulsations more clearly; and smoothed magnetograms (trend) X T (t) which describe the magnetic bay.…”

“…Figure 1: Map showing location of Antarctic stations and geomagnetic projection of the Greenland stations. same technique has been used before to isolate Pi2 pulsations from the onset variations [Martines-Bedenko et al, 2017]. Thus, upon data processing we have produced the following plots: stacked raw magnetograms of all 3 components; detrended magnetograms X d (t) which show ULF pulsations more clearly; and smoothed magnetograms (trend) X T (t) which describe the magnetic bay.…”