Multi-instrument observations of the solar eclipse on 20 March 2015 and its effects on the ionosphere over Belgium and Europe

Abstract

A total solar eclipse occurred on 20 March 2015, with a totality path passing mostly above the North Atlantic Ocean, which resulted in a partial solar eclipse over Belgium and large parts of Europe. In anticipation of this event, a dedicated observational campaign was set up at the Belgian Solar-Terrestrial Centre of Excellence (STCE). The objective was to perform high-quality observations of the eclipse and the associated effects on the geospace environment by utilising the advanced space-and ground-based instrumentation available to the STCE in order to further our understanding of these effects, particularly on the ionosphere. The study highlights the crucial importance of taking into account the eclipse geometry when analysing the ionospheric behaviour during eclipses and interpreting the eclipse effects. A detailed review of the eclipse geometry proves that considering the actual obscuration level and solar zenith angle at ionospheric heights is much more important for the analysis than at the commonly referenced Earth's surface or at the plasmaspheric heights. The eclipse occurred during the recovery phase of a strong geomagnetic storm which certainly had an impact on (some of) the ionospheric characteristics and perhaps caused the omission of some ''low-profile'' effects. However, the analysis of the ionosonde measurements, carried out at unprecedented high rates during the eclipse, suggests the occurrence of travelling ionospheric disturbances (TIDs). Also, the high temporal and spatial resolution measurements proved very important in revealing and estimating some finer details of the delay in the ionospheric reaction and the ionospheric disturbances.

Ionospheric Effects During the Total Solar Eclipse Over Southeast Asia‐Pacific on 9 March 2016: Part 1. Vertical Movement of Plasma Layer and Reduction in Electron Plasma Density

“…The results of these research investigations add to the list of long‐standing scientific literature from earlier studies on ionospheric effects of solar eclipse, which had started from the beginning of the 20th century (e.g. Burton & Boardman, ; He et al, ; Jakowski et al, ; Ledig et al, ; Munro & Heisler, ; Salah et al, ; Stankov et al, and references therein).…”

The Belgian Space Weather Observatory in Dourbes

“…Also designed, developed, and programmed are robust algorithms for nowcast and short-/long-term forecast of geospace plasma parameters by utilising ground-based (ionospheric incidence sounding, geomagnetic, cosmic rays) and space-based (GNSS, LEO satellite) measurements (Spits & Warnant 2008 RMI is also actively involved in the research activities of the Belgian Solar-Terrestrial Centre of Excellence (http://www.stce.be). For example, a joint recent multi-instrument observation campaign focused on the solar eclipse effects on the geospace environment (Verhulst et al 2016;Stankov et al 2017). Over the years, the team has participated in and managed several national and international research projects funded by the Belgian Government, European Commission, ESA, NATO, etc.…”

Height Dependency of Solar Eclipse Effects: The Ionospheric Perspective

“…Solar eclipses have a strong impact on the ionosphere because the majority of the ionization in the ionosphere is due to the direct solar radiation. During the eclipse itself a sharp decrease in the ionization level is observed, followed by a return to normal daytime conditions shortly after the end of the eclipse (Bamford, 2001;Stankov et al, 2017;Verhulst et al, 2016). Often the decrease in maximal ion density is also associated with a change in height of the ionospheric F 2 layer as well as changes in the temperature of both the neutral and ionized species (Rishbeth, 1968(Rishbeth, , 1970.…”

“…Given the rapid onset and passage of eclipses, in comparison with the typical relaxation times of ionospheric disturbances, during a total solar eclipse the ionosphere is promptly forced out of both photochemical and diffusive equilibrium (Müller-Wodarg et al, 1998), and eclipse-associated perturbations can linger on after the local occurrence of the maximal eclipse. Consequently, some eclipse effects on the ionosphere come with a delay, which can be quite substantial in some circumstances (Hoque et al, 2016;Stankov et al, 2017). In addition to the direct impact locally, that is, along the path of obscuration, a solar eclipse can induce far reaching wave-like phenomena traveling away from the path (Abidin Abdul Rashid et al, 2006;Afraimovich et al, 2000;Altadill et al, 2001;Mošna et al, 2018;Verhulst & Stankov, 2018).…”