ULF Waves Modulating and Acting as Mass Spectrometer for Dayside Ionospheric Outflow Ions

Abstract

Ionospheric outflow has been shown to be a dominant ion source of Earth's magnetosphere. However, most studies in the literature are about ionospheric outflow injected into the nightside magnetosphere. We still know little about ionospheric outflow injected into the dayside magnetosphere and its further energization after it enters the magnetosphere. Here, with data from Magnetospheric Multiscale mission, we report direct observations of the modulation of dayside ionospheric outflow ions by ultralow frequency (ULF) waves. The observations indicate that the modulation is mass dependent, which demonstrates the possibility of using ULF waves as a mass spectrometer to identify ion species. Moreover, the measurement suggests that polarization drift may play a role in O+ modulation, which may lead to a true acceleration and even nonadiabatic behavior of O+. This interaction scenario can work throughout the whole magnetosphere and impact upon the plasma environment and dynamics.

Global Propagation of Magnetospheric Pc5 ULF Waves Driven by Foreshock Transients

“…Those waves can also energize cold plasma through wavefield‐induced E × B drift or drift‐bounce resonance (Adrian et al, 2004; B. Li et al, 2019; Z.‐Y. Liu et al, 2019; Ren et al, 2017; Yue et al, 2016). In the radiation belts, their spectral characteristics have also been used to evaluate radial diffusion coefficients (Brautigam et al, 2005; Huang et al, 2010; Perry et al, 2005; Ukhorskiy et al, 2005) and study the dynamic variability of radiation belt electrons (Fei et al, 2006; Kress et al, 2007).…”

Modulation of ionospheric outflow ions by EMIC waves in the dayside outer magnetosphere

“…Moreover, these cold ions sometimes exhibit periodic variations in the ion energy spectrogram. [19][20][21] The modulation of cold ions is caused by ultralow frequency (ULF) waves in the Pc5 band ($a few mHz). [19][20][21][22] ULF waves are common in the Earth's magnetosphere and can efficiently transfer energy with energized particles.…”

“…[19][20][21] The modulation of cold ions is caused by ultralow frequency (ULF) waves in the Pc5 band ($a few mHz). [19][20][21][22] ULF waves are common in the Earth's magnetosphere and can efficiently transfer energy with energized particles. [23][24][25][26][27][28][29][30][31] Recently, the ULF wave-induced cold ion enhancements are clearly explored from Magnetospheric Multiscale (MMS) mission.…”

“…[23][24][25][26][27][28][29][30][31] Recently, the ULF wave-induced cold ion enhancements are clearly explored from Magnetospheric Multiscale (MMS) mission. 20,21 Through the E Â B drift resulting from ULF waves, low-energy cold ions (a few eV) are converted to ions with energy exceeding the minimum energy threshold of the MMS plasma instrument, which induces these hidden cold ions reaching the onboard detector. 20,21 Also, ULF waves can naturally produce periodic variations of energy of cold ions due to their electric fluctuations.…”

Evolutions of equatorial ring current ions during a magnetic storm

“…Many studies have been made of ULF wave generation and effects (e.g. Liu ZY et al, 2019; Zong Q‐G et al, 2009, 2012). The sources of ULF waves in the Earth's magnetosphere are generally thought to be external solar wind disturbances and internal plasma instabilities (Liu W et al, 2013).…”