Equatorial Spread-F (ESF) Weather: Day-to-Day Variability
Abstract
We are concerned with plasma structures that develop in the nighttime equatorial F layer. They are generically referred to as equatorial spread F (ESF). As with ground (or space) weather, their unpredictability on a day-to-day (D2D) basis is of particular concernbecause ESF includes a broad spectrum of structural scale sizes that spans seven orders of magnitude, from 1000 km to 10 cm. Consequently, their effects are widespread and have broad impact. Radio effects, which could include group delay, angle of arrival, signalfading, scintillation, and scatter, can seriously degrade the performances of communication, navigation and radar systems. We propose to investigate the physics responsible for this D2D variability. There is mounting evidence that the D2D variability in plasma perturbations begins with perturbations in the neutral gas, which are then transferred to the plasma through neutral-ion (NI) coupling. Once perturbations are transferred to the plasma, growth becomes possible via an interchange process in the bottomside of the equatorial F layer. A fundamental issue is whether NI coupling and plasma-perturbation growth are controlled by the F-region dynamo, or whether they are controlled at lower altitudes and earlier times by the E-region dynamo. This research is groundbreaking because it will focus on understanding the roles of the E- and F-region dynamos in the seeding of ESF in the late-afternoon sector. The proposed approach is novel in that it will seek a space-time descriptions of large-scale plasma structure (in bottomside of the equatorial F layer) by using a research ionosonde with angle-of-arrival measurement capability, and spaced receivers to scan the spatial structure with radio transmissions from the COSMIC-2 satellites. The results are expected to clarify the physics responsible for ESF weather, and these findings could possibly lead to forecastability as early as the afternoon sector. Progress in understanding D2D variability in ESF weatheris expected to benefit systems that rely on the avoidance of ESF.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 08, 2024
- Source ID
- N000142412328
Entities
People
- Roland Tsunoda
Organizations
- Office of Naval Research
- SRI International
- United States Navy