Collaborative Research: Exploring Low-Latitude Ionospheric Irregularities in the Upper E-Region Valley Using Observations, Theory, And Simulations

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This proposal combines modeling tools with incoherent scatter radar measurements to investigate the sources of radar echoes scattered from the equatorial ionosphere near 150 km. When plotted in the altitude-time plane, these echoes resemble a "necklace". Intricately structured backscatter first appears at dawn near 150 km, descends to ~130 km by midday, lofts to150 km by late afternoon, and disappears at sunset. The cause of these echoes remained largely unknown until 2016, when the PIs plausibly argued they were manifestations of photoelectron-driven electron waves. The goal of this work is to build a cohesive, physics-based, system-science understanding of the 150-km echoes. Under this new award, the PIs will continue their theoretical and experimental investigations by incorporating additional processes into their model, and comparing with Jicamarca radar and ionosonde data. Broader impacts include mentoring of graduate, undergraduate, and high-school students. Advancing understanding of ionospheric physics, and being able to interpret ionospheric radar signatures and ionospheric structuring benefits space weather modeling and prediction. The 2016 work received much attention in the popular press, and thus stimulated public interest in plasma physics research.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.