Day 4

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Paper title Irregular magnetic field fluctuations in the ionosphere; Analysis of the long-term high-frequency magnetic field record of the Swarm mission
Authors
  1. Peter Kovacs Wigner Reseach Centre for Physics Speaker
  2. Balázs Heilig Eötvös Loránd University
Form of presentation Poster
Topics
  • B2. Earth Explorer missions
    • B2.05 Swarm - ESA's Extremely Versatile Magnetic Field and Geospace Explorer
Abstract text The plasma of the ionosphere is abundant with small-scale (100-200 km) irregularities that may result in the distortion and loss of radio signals of GNSS satellites, thus the corruption of ground-based GPS measurements. The plasma irregularities are accompanied by scale-dependent turbulent fluctuations in the magnetic field. Within the framework of the recently finished EPHEMERIS project, we carried out the quasi real-time monitoring of possible occurrences of nonlinear magnetic field irregularities along the orbits of the Swarm satellite triplet. Statistical analysis was applied. It was conjectured that intermittent turbulent plasma fluctuations involved the non-Gaussian behaviour of probability density functions (PDF) of the corresponding physical parameters (magnetic field, plasma density, temperature, etc.).
In the presentation we analyse the temporal and spatial distribution of the nonlinear irregularities of the high-pass filtered field-aligned (i.e., compressional) and transverse magnetic field fluctuations. It is shown that the most intensive irregularities in the transverse field appear near the auroral oval boundaries, as well as close to the plasmapause. On the other hand, it is also revealed that compressional and transverse fluctuations exhibit intermittent behaviour also about the dip equator, symmetrically near the 10° latitude in both hemispheres. The latter finding is the consequence of equatorial spread F (ESF) or equatorial plasma bubble (EPB) phenomena. The study also concerns the space weather consequences of the detected magnetic field irregularities. First, we investigate the correlation between GPS signal loss events experienced onboard Swarm satellite and the irregular state of the ionosphere plasma. Secondly, we study the influence of irregularities on GNSS radio signal distortions via the processing of amplitude and phase scintillation records of ground GNSS stations. It is shown that radio signals are clearly distorted by the magnetic irregularities detected in the equatorial region, while this coincidence is not undoubtedly demonstrated near the plasmapause and the auroral oval boundaries. It is conjectured that the controversial findings can be explained by the different origin of the observed magnetic irregularities at low and high latitudes, that is plasma depletion near the Equator, while field aligned currents or plasma waves in the high-latitude region.