Research Projects

During geomagnetic storms, a portion of the solar wind energy is transferred into the polar ionosphere-thermosphere system, leading to enhanced Joule heating in the polar regions.This Joule heating drives thermospheric winds, which in turn modify the thermospheric density. The increase in thermospheric density subsequently enhances atmospheric drag on Low-Earth-Orbit (LEO) satellites and space debris. Thermospheric density is a major source of uncertainty in determining the position and velocity of satellites at LEO altitudes. This uncertainty impacts several critical areas of space operations, including orbital lifetime estimation, and the maintenance of space object catalogs etc. The majority of weather monitoring satellites and satellites for geophysical studies operate at LEO altitudes; the International Space Station (ISS) is in LEO at about 400 km. India’s proposed space station, Bharathiya Antariksha Station (BAS), is also planned to be in LEO (400–450 km). The recent loss of 38 out of 42 Starlink satellites in early February 2022, triggered by a relatively minor geomagnetic storm (Dst of −66 nT, Kp of 5), highlights the critical need for accurate and timely space weather forecasting. A significant difference up to 70 percentage between observations and model predictions noted during this event further implies the need for comprehensive studies on the performance of different models during various space weather events. Earlier studies were based on specific events, primarily focusing on major geomagnetic storms. In fact, comprehensive studies on storm-induced changes in thermospheric density across all storm types remain rare. The proposed work aims to examine the thermospheric response to all geomagnetic storms with Dst less than -50 nT (including hundreds of events covering minor, moderate, major, and double storms, i.e., consecutive storms) that occurred during the last decade, and to quantify their variability. Using a decade of Swarm A and C satellite data, this study will establish a global reference for quiet-time variations in thermospheric density across different local times, seasons, and levels of solar activity. Deviations from this reference level during various types of geomagnetic storms will be quantified to derive an index for geo-effectiveness in terms of thermospheric density variations. Another main focus of this work is to estimate the coherence between observations and model-predicted thermospheric densities for storms with different characteristics. This analysis will provide insight into the geophysical conditions under which observations and models align well and those in which they significantly diverge, ultimately helping to improve model performance. Additionally, basic Artificial Neural Network models will be developed to predict indices representing the geo-effectiveness of different geomagnetic storms on thermospheric density variations.

Space weather, Thermosphere density, Geo-effectiveness, Geomagnetic storms