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On the Relationship between Low Latitude Scintillation Onset and Sunset Terminator over Africa

Mersha, Mogese Wassaie and Lewi, Elias and Jakowski, Norbert and Wilken, Volker and Berdermann, Jens and Kriegel, Martin (2021) On the Relationship between Low Latitude Scintillation Onset and Sunset Terminator over Africa. Remote Sensing (13), p. 2087. Multidisciplinary Digital Publishing Institute (MDPI). doi: 10.3390/rs13112087. ISSN 2072-4292.

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Official URL: https://www.mdpi.com/2072-4292/13/11/2087/


The solar terminator is a moving boundary between day-side and night-side regions on the Earth, which is a substantial source of perturbations in the ionosphere. In the vicinity of the solar terminator, essential parameters like S4 index measurements are widely analyzed in order to monitor and predict perturbations in the ionosphere. The utilization of the scintillation index S4 is a well-accepted approach to describe the amplitude/intensity fluctuation of a received signal, predominantly caused by small-scale irregularities of the ionospheric plasma. We report on the longitudinal daily and seasonal occurrence of GNSS signal scintillations, using the data derived from the GNSS stations in Bahir Dar, Ethiopia, Lomé, Togo and Dakar, Senegal. The observed seasonal climatology of GNSS signal scintillations in equatorial Africa is adequately explained by the alignment of the solar terminator and local geomagnetic declination line. It should be pointed out that the strongest scintillations are most frequently observed during the time when the solar terminator is best aligned with the geomagnetic declination line. At all three stations, the comparison of computational and observational results indicated that the scintillation activity culminated around equinoxes in the years 2014, 2015 and 2016. Comparatively, the western equatorial Africa sector has the most intense, longest-lasting, and highest scintillation occurrence rate in equinoctial seasons in all three years. For the first time, we show that the seasonal variation of the scintillation peaks changes systematically from west to east at equatorial GNSS stations over Africa. A detailed analysis of the solar day–night terminator azimuth at ionospheric heights including the time equation shows that the scintillation intensity has a maximum if the azimuth of the terminator coincides with the declination line of the geomagnetic field. Due to the remarkable change of the declination by about 10° at the considered GNSS stations, the distance between scintillation peaks increases by 46 days when moving westward from the Bahir Dar to the Dakar GNSS station. The observations agree quite well with the computational results, thus confirming Tsunoda’s theory

Item URL in elib:https://elib.dlr.de/143409/
Document Type:Article
Title:On the Relationship between Low Latitude Scintillation Onset and Sunset Terminator over Africa
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Mersha, Mogese WassaieInstitute for Solar-Terrestrial PhysicsUNSPECIFIED
Lewi, Eliasnstitute of Geophysics, Space Science and Astronomy, Addis Ababa UniversityUNSPECIFIED
Jakowski, NorbertUNSPECIFIEDhttps://orcid.org/0000-0003-3174-2624
Wilken, VolkerUNSPECIFIEDhttps://orcid.org/0009-0001-6783-7062
Berdermann, JensUNSPECIFIEDhttps://orcid.org/0000-0002-3308-4584
Kriegel, MartinUNSPECIFIEDhttps://orcid.org/0000-0001-5543-180X
Date:26 May 2021
Journal or Publication Title:Remote Sensing
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:p. 2087
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
Series Name:Space Weather: Observations and Modeling of the Near Earth Environment
Keywords:equatorial ionosphere; solar terminator; ionospheric irregularities; scintillation; global navigation satellite systems (GNSS)
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Project Space weather research
Location: Neustrelitz
Institutes and Institutions:Institute for Solar-Terrestrial Physics > Space Weather Impact
Deposited By: Berdermann, Dr Jens
Deposited On:16 Aug 2021 10:22
Last Modified:28 Mar 2023 23:59

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