Nighttime magnetic field fluctuations in the topside ionosphere at midlatitudes and their relation to medium‐scale traveling ionospheric disturbances: The spatial structure and scale sizes. Issue 8 (12th August 2015)

• Record Type: Journal Article
• Authors: Park, Jaeheung; Lühr, Hermann; Kervalishvili, Guram; Rauberg, Jan; Michaelis, Ingo; Stolle, Claudia; Kwak, Young‐Sil
• Is Part Of: Journal of geophysical research. Volume 120:Issue 8(2015:Aug.)
• Page Start: 6818
• Page End: 6830
• Publication Date: 2015-08-12
• Subjects: midlatitude nighttime magnetic fluctuation -- nighttime MSTID -- Swarm constellation; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2015JA021315
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: Previous studies suggested that electric and/or magnetic field fluctuations observed in the nighttime topside ionosphere at midlatitudes generally originate from quiet time nocturnal medium‐scale traveling ionospheric disturbances (MSTIDs). However, decisive evidences for the connection between the two have been missing. In this study we make use of the multispacecraft observations of midlatitude magnetic fluctuations (MMFs) in the nighttime topside ionosphere by the Swarm constellation. The analysis results show that the area hosting MMFs is elongated in the NW‐SE (NE‐SW) direction in the Northern (Southern) Hemisphere. The elongation direction and the magnetic field polarization support that the area hosting MMFs is nearly field aligned. All these properties of MMFs suggest that they have close relationship with MSTIDs. Expectation values of root‐mean‐square field‐aligned currents associated with MMFs are up to about 4 nA/m 2 . MMF coherency significantly drops for longitudinal distances of ≥1 ∘ . Key Points: Midlatitude magnetic fluctuations are elongated in NW‐SE (SW‐NE) in NH (SH) Areas hosting midlatitude magnetic fluctuations are likely to be field aligned Zonal coherence length of the fluctuations is smaller than 150 km