JSG T.27

Introduction

Consequences of upper-atmosphere conditions on human activity underscore the necessity to better understand and predict effects of the magnetosphere-ionosphere-thermosphere (MIT) processes and of their coupling. This will prevent from their potential detrimental effects on orbiting, aerial and ground-based technologies. For instance, major concerns include the perturbation of electromagnetic signals passing through the ionosphere for an accurate and secure use of global navigation satellite systems (GNSS), and the lack of accurate aerodynamic-drag models required for accurate tracking, decay and re-entry calculations of low Earth orbiters (LEO), including manned and unmanned artificial satellites. In addition, ground power grids and electronics of satellites could be influenced, e.g., by the magnetic field generated by sudden changes in the current system due to solar storms.

Monitoring and predicting Earth’s upper atmosphere processes driven by solar activity are highly relevant to science, industry and defence. These communities emphasize the need to increment the research efforts for better understanding of the MIT responses to highly variable solar conditions, as well as detrimental space weather effects on our life and society. On one hand, electron-density variations produce perturbations in speed and direction of various electromagnetic signals propagated through the ionosphere, and reflect as a time-delay in the arrival of the modulated components from which pseudo-range measurements of GNSS are made, and an advance in the phase of signal’s carrier waves which affects also carrier-phase measurements. On the other hand, an aerodynamic drag associated with neutral-density fluctuations resulting from upper atmospheric expansion/contraction in response to variable solar and geomagnetic activity increases drag and decelerates LEOs, dwindling the lifespan of space-assets, and making their tracking difficult.

Through interrelations, dependencies and coupling patterns between ionosphere, thermosphere and magnetosphere variability, this JSG aims to improve the understanding of coupled processes in the MIT system, and considerations of the solar contribution. In addition, tides from the lower atmosphere forcing can feed into the electrodynamics; they have a composition effect leading to changes in the MIT system. In this scheme, our tasks are addressed to exploit the knowledge of the tight MIT coupling by investigating multiple types of magnetosphere, ionosphere and thermosphere observations. The final outcome will help to enhance the predictive capability of empirical and physics-based models through interrelations, dependencies and coupled patterns of variability between essential geodetic variables.

Objectives

• Characterize and parameterize global modes of MIT variations associated with diurnal, seasonal and space weather drivers as well as the lower atmosphere forcing.
• Determine and parameterize mechanisms responsible for discrepancies between observables and present models.
• Detect and investigate coupled processes in the MIT system for the deciphering of physical laws and principles such as continuity, energy and momentum equations and solving partial differential equations.

Planned Activities

• Presenting research findings at major international geodetic or geophysical conferences, meetings, and workshops.
• Interacting with related IAG Commissions and GGOS.
• Monitoring research activities of the JSG members and of other scientists, whose research interests are related to the scopes of SG
• Organizing a session at the Hotine-Marussi Symposium 2022.
• Organizing working meetings at international symposia and presentation of research results at appropriate sessions.

Members

Andres Calabia Aibar (China), chair
Emmanuel Abiodun Ariyibi (Nigeria)
Toyese Tunde Ayorinde (Brazil)
Olawale S. Bolaji (Nigeria)
Oluwaseyi Emmanuel Jimoh (Nigeria)
Gang Lu (USA)
Naomi Maruyama (USA)
Astrid Maute (USA)
Piyush M. Metha (USA)
Charles Owolabi (Nigeria)
Liang Yuan (China)