Scientists from St Petersburg University infer that strong increases of energetic charged particle flux during cosmic substorms are formed in the vicinity of an orbit densely populated with satellites
Physicists from St Petersburg University together with their colleagues from the Southern University of Science and Technology (Shenzhen, China) and the Institute of Geophysics and Planetary Physics (California, USA) have carried out a detailed modelling of the process of charged particle injection during cosmic substorms. In particular, they have found out that the large flux increase of such particles is formed in the region of geostationary orbit near the Earth’s equator. The study was carried out in the Ozone Layer and Upper Atmosphere Research Laboratory at St Petersburg University. The Laboratory was established within the framework of the mega-grant programme of the Ministry of Science and Higher Education of the Russian Federation.
Injection is a significant, short-term local increase in the flux of energetic charged particles in the outer part of the Earth’s radiation belt, which is the near-Earth space containing high fluxes of energetic protons and electrons. Injection occurs due to the rapid transfer from the magnetotail located on the night side of the Earth, to the inner magnetosphere of these charged particles, which experience significant acceleration during this transfer. Injection occurs by means of fast flow jets, which are generated in the magnetotail at a distance of 20 to 30 Earth radii.
The results of the research supported by a grant from the Russian Science Foundation are published in the journal JGR: Space Physics.
It is important to note that, according to the scientists’ observations, the intensity and penetrating ability of the jets increase particularly strongly during periods of magnetospheric substorms. Magnetospheric substorms are disturbances in near-Earth space associated with partial disruption of the magnetotail current sheet and rapid release of the accumulated magnetic energy.
In addition to the fact that injections replenish the Earth’s outer radiation belt, the fluxes of energetic electrons sharply increasing during injections lead to disruption of satellite systems. Among other important consequences, especially important are the precipitation of energetic electrons into the atmosphere at high latitudes during substorms, which disrupt radio communications, affect satellite navigation, and may have long-term effects on stratospheric ozone and, probably, climate. These ejections are triggered by injections and are closely related to them.
The work was based on supercomputer simulation using a self-consistent model that is adequate (in terms of physics) and realistic (in terms of initial configuration). The model showed that we correctly reproduce the injection intensity and the main known dynamical characteristics of injections and associated ejections. Satellite data confirmed the model’s effectiveness.
Viktor Sergeev, Member of the Ozone Layer and Upper Atmosphere Research Laboratory, Professor in the Department of Earth Physics at St Petersburg University
The modelling showed that the largest increase in the energetic electron fluxes occurs in the frontal region of the flow jet. The maximum flux increases of energetic charged particles were localised in the vicinity of the geostationary orbit, a circular orbit at a distance of 6.6 Earth radiinear the Earth’s equator, which makes this area unique in the magnetosphere in terms of space weather.
Calculations of the substorm effect of on particle injection had been made before, but to describe the generation and braking of plasma jets in the inner magnetosphere, they were crude and did not include self-consistently a description of the energetic particles themselves. The new model takes into account the magnetic drift of particles and other important parameters. This model makes it possible to see how the injection is formed, how it is transformed into a cloud of particles drifting around the Earth and precipitating into the atmosphere.
For reference: earlier, the researchers from the Ozone Layer and Upper Atmosphere Research Laboratory of St Petersburg University found that magnetic storms destroy up to a quarter of the earth’s ozone layer in the mesosphere in one day. The recorded destruction is at an altitude of about 75 km.
St Petersburg University, the oldest university in Russia was founded on 28 January (8 February) 1724. This is the day when Peter the Great issued a decree establishing the University and the Russian Academy of Sciences. Today, St Petersburg University is an internationally recognised centre for education, research and culture. In 2024, St Petersburg University will celebrate its 300th anniversary.
The plan of events during the celebration of the anniversary of the University was approved at the meeting of the Organising Committee for the celebration of St Petersburg University’s 300th anniversary. The meeting was chaired by Dmitry Chernyshenko, Deputy Prime Minister of the Russian Federation. Among the events are: the naming of a minor planet in honour of St Petersburg University; the issuance of bank cards with a special design; the creation of postage stamps dedicated to the history of the oldest university in Russia; and the branding of the aircraft of the Rossiya Airlines to name just a few. Additionally, the University has launched a website dedicated to the upcoming holiday. The website contains information about outstanding University staff, students, and alumni; scientific achievements; and details of preparations for the anniversary.