Collaborative Research: Ionospheric Density Response to American Solar Eclipses Using Coordinated Radio Observations with Modeling Support

Solar eclipses are unique celestial phenomena that offer excellent opportunity to explore the impacts of reduced solar flux on the ionosphere. As the moon’s shadow sweeps across the contiguous United States, it provides a natural laboratory to study the ionosphere—a partially ionized region of our atmosphere that plays a crucial role in radio communication, navigation, and space weather. During a solar eclipse, the reduction in solar radiation leads to a decrease in ionization. The investigators plan to take advantage of the upcoming solar eclipse in 2024 through coordinated multi-instruments observations of ionospheric parameters. The proposed work will deepen our understanding of the chemical and dynamical processes in the ionosphere-thermosphere (IT) system. Such events impact the plasma density, which adversely affects High Frequency (HF: 3-30 MHz) propagation and communication signals. While the macroscopic effects on the IT response are well understood, the detailed features controlling the ionospheric density including the transport in the F-region and topside ionosphere remain unclear. The project will strengthen collaborations with the citizen science community, support two early-career scientists and an undergraduate summer student. This project benefits society by improving communication reliability, enhancing space weather predictions, and supporting education and diversity in STEM fields. One of the main objectives of the proposal is to understand and quantify the relative importance of external forces on the ionospheric density responses to the October 2023 and April 2024 solar eclipses as observed by HF sounding and compare the findings with the August 2017 solar eclipse. The proposal will focus on the following scientific topics: 1. Quantification of Eclipse-Driven Ionospheric Changes: the project seeks to understand how solar eclipses impact the ionosphere's electron density. It plans to investigate variations in the F-region height (HmF2) and the occurrence of the ionospheric G-condition (where NmF1≥NmF2), (2) Identification of Controlling Factors: By analyzing data from ground-based HF facilities, the researchers will quantify the relative importance of various factors in determining the ionospheric responses, including reduced EUV Flux, thermospheric winds, photoelectron transport and heating. The proposed scientific investigation involves the use of the SuperDARN, the Millstone Hill Incoherent Scatter Radar (MHISR), and HamSCI HF observations. This work encourages training and education of the younger generation and facilitates capacity building through the involvement of early career scientists. 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.