J. Space Weather Space Clim.
Volume 12, 2022
Topical Issue - Ionospheric plasma irregularities and their impact on radio systems
|Number of page(s)||15|
|Published online||18 November 2022|
The refractive and diffractive contributions to GPS signal scintillation at high latitudes during the geomagnetic storm on 7–8 September 2017
Department of Space Physics, Electronic Information School, Wuhan University, 430072 Wuhan, China
2 Hubei Luojia Laboratory, 430079 Wuhan, China
3 Department of Physics, University of Oslo, PO Box 1048, Blindern, 0316 Oslo, Norway
4 No. 22nd Research Institute, CETC, 266107 Qingdao, Shandong, China
5 Birkeland Centre for Space Science, Department of Physics and Technology, University of Bergen, PO Box 7803, 5020 Bergen, Norway
6 University Centre in Svalbard, N-9171 Longyearbyen, Norway
* Corresponding author: firstname.lastname@example.org
Accepted: 24 October 2022
Different indices have been used to reflect, or monitor the ionospheric scintillation, e.g. the detrended carrier phase, σφ, S4, the rate of change of the vertical total electron content index (vROTI), as well as the ionosphere‐free linear combination (IFLC) of two carrier phases. However, few studies have been performed to investigate the refractive and diffractive contributions to these indices, especially during geomagnetic storms. In this study, we analyze the high-resolution (50 Hz) phase and amplitude measurements from four high-latitude stations in Svalbard, Norway during the geomagnetic storm on 7–8 September 2017. Our results show that at high latitudes, the high-pass filter with a standard cutoff frequency of 0.1 Hz sometimes cannot effectively remove the refraction-driven phase variations, especially during the geomagnetic storm, leading to a remaining refraction contribution to the detrended carrier phase and σφ when scintillation happens. In the meanwhile, as vROTI is sensitive to the TEC gradients, regardless of small- or large-scale ionospheric structures, both refraction and diffraction effects can cause visible fluctuations of vROTI. For most of the scintillation events, the phase indices (including detrended carrier phase, σφ, and vROTI), IFLC, and S4 show consistent fluctuations, indicating that diffraction usually occurs simultaneously with refraction during scintillation. One interesting feature is that although the IFLC and S4 are thought to be both related to the diffraction effect, they do not always show simultaneous correspondence during scintillations. The IFLC is enhanced during the geomagnetic storm, while such a feature is not seen in S4. We suggest that the enhanced IFLC during the geomagnetic storm is caused by the increased high-frequency phase power, which should be related to the enhanced density of small-scale irregularities during storm periods.
Key words: Refraction / Diffraction / Plasma irregularity / Scintillation / Geomagnetic storm
© K. Herlingshaw et al., Published by EDP Sciences 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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