Alfvén velocity sudden increase as an indicator of the plasmapause

Rubtsov, Aleksandr V.; Nosé, M.; Matsuoka, A.; Kasahara, Yoshiya; Kumamoto, A.; Tsuchiya, F.; Shinohara, I.; Miyoshi, Yoshizumi

doi:10.1016/j.jastp.2023.106040

Cited by 2 publications

(3 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During geomagnetically disturbed time, toroidal waves have very high occurrence rate, especially at the dusk and pre-midnight sectors (Figure 3b). But this high occurrence rate suddenly drops near L = 6 at the dusk-midnight sector, that is 1 R E outward from the average plasmapause location, L PP = 5.1 (see Rubtsov et al (2023a)). The occurrence rate becomes much lower during quiet time, and the area of occurrence rate maximum moves outward by ∼1 R E following the plasmasphere expansion (Figure 3f).…”

Section: Toroidal Wavesmentioning

confidence: 98%

“…To apply this criterion correctly, we projected electron density data onto the geomagnetic equator assuming dipole magnetic field: n eq = n cos 2 α θ , where n and n eq are electron density at the satellite position and at the equator, respectively, θ is the magnetic latitude, and α is a power index defining a number density decrease from the Earth (Cummings et al., 1969). We chose α = 2 for further calculations (Rubtsov et al., 2023a; Takahashi & Denton, 2021). Also, upper and lower density drop limits were introduced.…”

Section: Plasmapause Detectionmentioning

confidence: 99%

“…But the plasmapause can be located at L < 4 during disturbed geomagnetic conditions. We think that this limitation will not change the results significantly, because most of the time under investigation was geomagnetically quiet and the average plasmapause location is 5.1 ± 1.1 R E (see Rubtsov et al (2023a), for details).…”

Section: Plasmapause Detectionmentioning

confidence: 99%

See 2 more Smart Citations

Plasmasphere Control of ULF Wave Distribution at Different Geomagnetic Conditions

Rubtsov,

Nosé,

Matsuoka

et al. 2023

JGR Space Physics

Self Cite

View full text Add to dashboard Cite

Magnetic storms and substorms cause global disturbances in the Earth's magnetosphere. Plasma clouds injected from the magnetotail during storm or substorm drift around the Earth and generate ultra‐low frequency (ULF) waves via various mechanisms. At the same time, the inner part of the magnetosphere called plasmasphere is filled with cold particles and its characteristics are sensitive to the geomagnetic activity level. Previous theoretical and some observational studies suggested plasmasphere and its boundary, plasmapause, are special regions for ULF waves to interact with charged particles. We present a statistical analysis of ULF waves during different geomagnetic conditions. We utilized Arase satellite magnetic field and electron density measurements from March 2017 to December 2020 to investigate spatial distribution of ULF waves and its dependence on the plasmapause location. A 1–2 RE gap between the plasmapause and a region of high transverse waves occurrence rate was found. This gap keeps during quiet geomagnetic conditions when plasmasphere expands, and we concluded that the plasmapause controls the ULF wave distribution in the magnetosphere. ULF wave occurrence rate significantly decreases at quiet time, but dayside and dawnside maxima still occur for poloidal and compressional, and toroidal waves, respectively. Thus, we can distinguish internally and externally excited waves. Average wave frequency distribution revealed field‐line resonance character of toroidal waves as frequency increases toward the Earth. Poloidal and compressional waves distributions clearly distinguish low frequency externally excited waves and high frequency storm‐time pulsations.

show abstract

Section: Toroidal Wavesmentioning

confidence: 98%