C: Space Studies of the Upper Atmospheres of the Earth and Planets Including Reference Atmospheres

C0.1 Multi-instrumental Approach as a Mitigation Strategy for Space Weather Hazard

Space weather refers to the variations in the Sun, solar wind, magnetosphere, ionosphere, and thermosphere, which can affect the performance of a wide range of space-borne and ground-based technological systems and pose a danger to human health and safety. Space weather is mainly driven by extreme solar events such as Coronal Mass Ejections (CMEs), Solar Flares (SFs) and Solar Energetic Particles (SEPs). CMEs are known to induce intense Geomagnetic Storms (GSs). Communication satellites in high orbits, power grids, as well as oil and gas pipelines on the ground can be adversely impacted during intense GS. Particularly, the exposure and threat to power grids and pipelines depends on the magnitude of Geomagnetically Induced Currents (GICs), which represent the end of the chain of an extreme space weather event, ranging from the Sun to the surface of the Earth. In addition, storm-time perturbations in the ionosphere affect high-frequency (HF) radio communication and GNSS navigation signals, and enhance satellite orbital drag effects in low-Earth orbit (LEO, <1000 km altitude), possibly causing track uncertainties and eventually the downfall of satellites. It is to be noted that fast halo CMEs are often associated with SEPs which can pose a momentous radiation hazard for astronauts and equipment in space. Clearly, the aftermath of a severe space weather event could be quite devastating, particularly in this era of humanity’s increase reliance on critical GNSS technologies. A multi-instrumental approach, by using ground-based observations (magnetometers, magnetotelluric stations, ionospheric sounders, GNSS receivers, etc.), LEO satellite (AMPERE, Swarm, CSES, etc.) measurements, and both magnetospheric (GOES, MMS, Geotail, etc.) and interplanetary satellites (ACE, Wind, DISCOVR), is not only fundamental to enhancing our understanding of the physics driving the changes in the geospace environment, but also important in the development of mitigating strategies vis-à-vis future space weather impact on critical engineering system and infrastructure.

C0.2 Impact Assessment of Extreme Space Weather Events of 2024 on the Near Earth Space Environment and Technological Systems

Space weather refers to a multitude of phenomena occurring at the sun, interplanetary medium, magnetosphere, ionosphere, thermosphere over periods ranging from hours to years. These naturally occurring processes have the potential to adversely affect the performance and reliability of space-borne and ground-based technological systems and can endanger several facets of human life. Recent extreme space weather events occurred in May and October 2024 triggered severe modifications in the geospace environment leading to G5 and G4 class geomagnetic storms respectively. The space weather event of May 2024 comprises of 11 X class flares and most powerful coronal mass ejection resulting the strongest geomagnetic storm of the past two decades. There was a remarkable impact of these two space weather events, with auroras observed worldwide extending up to low latitudes demonstrating a significant solar-terrestrial coupling. Severe disruptions were also experienced by the ground and satellite based technologies worldwide during these storms. These space weather events provide a unique opportunity to explore the complex processes in the Solar-Wind-Magnetosphere-Thermosphere-Ionosphere system to understand and formulate mitigation strategies to cater the needs of ever increasing technological applications. Papers are invited in this session which is focussed to discuss the impacts of the above two space weather events on the geospace environment at varied spatio-temporal scales using ground and satellite based observations and model simulations including AI/ML techniques. Also, papers addressing the implications of these events on the space assets, satellite anomalies, operations and performance of ground and satellite based technologies are encouraged.