Space Weather Control of Equatorial Plasma Bubble Development

After sunset, the upper atmosphere above Earth's equator becomes unstable, and result in plumes of depleted plasma. These are referred to as equatorial plasma bubbles, which are manifestation of ionospheric irregularities. These significantly degrade the performance of radio communication and satellite positioning systems. Whether bubbles form on a given night is not reliably predictable, and the problem worsens during geomagnetic disturbances, when such events in the solar wind deposit energy into the upper atmosphere. This proposal aims to combine plasma density and thermospheric wind measurements from satellites with ground-based wind instruments and use physics-based models of the upper atmosphere to determine how, where, and why plasma bubbles are enhanced or suppressed during geomagnetic disturbances. Improving understanding of plasma bubbles is crucial for space weather prediction and simulation models. The proposal supports the career development of an early-career postdoctoral researcher. This proposal will help determine how equatorial plasma bubble (EPBs) development is modified during disturbed geomagnetic conditions and identifies the physical drivers responsible for their occurrence. It builds on preliminary results from the ionospheric connection explorer satellite data and will use other available satellite and ground-based observations. The researchers plan to use a superposed epoch analysis of several geomagnetic disturbance events. The other objective of the research is to identify physical drivers using observed thermospheric winds, modeled latitudinal gradients of the meridional wind at the dip equator validated against ground-based Fabry-Perot interferometers, and the flux-tube-integrated growth rate of the generalized Rayleigh-Taylor plasma instability from coupled model runs, all evaluated in the same superposed epoch framework. They plan to include data from solar maximum times, which increases the occurrence rates of both geomagnetic disturbances and EPBs. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.