Observational Analysis of Ionospheric Conductivity and E-Region Shorting at High Latitudes
Abstract
SRI International proposes a basic research project to investigate plasma conductivity in the high-latitude ionosphere, specifically to characterize how the conductivity profile varies in time and how it may impact the development of plasma irregularities. This project is expected to enhance ONR#s ability to model and forecast plasma dynamics in the ionosphere. Results may be used in conjunction with the existing Polar, Regional Ionosphere Sensing and Modeling (PRISM) effort to improve performance of the NextGen Ionosphere Model for Operations (NIMO), which is a noted goal of ONR#s Marine Meteorology and Space Weather program. The SRI project will contribute to determining when and where ionospheric effects occur that may adversely impact operationally critical Navy infrastructure, including communication, navigation, surveillance, and monitoring systems. Plasma conductivity impacts numerous aspects of ionospheric dynamics, including magnetosphere-ionosphere coupling and plasma irregularity development. and as such, it is a critical consideration for ionospheric models. However, many current models make do with empirical height-integrated estimates of conductance of key layers that are based on parameterized proxy estimates. The SRI study will improve upon this limited capability by utilizing a long-term (over a complete solar cycle) historical dataset of ionospheric profile measurements from two high-latitude advanced modular incoherent scatter radars (AMISRs) to create an empirical model of conductivity profiles that shows how they vary with time, season,solar cycle, and geomagnetic condition.The radars to be used in this project are the Resolute Bay Incoherent Scatter Radar North (RISR-N), located deep within the polar cap, and the Poker Flat Incoherent Scatter Radar (PFISR), which is situated on the Poker Flat Rocket Range in the auroral zone. Both of these facilities are owned by the National Science Foundation (NSF) and operated by SRI International to provide public scientific data and support basic research. AMISRs make remote measurements of basic plasma parameters, including electron density, along altitude profiles in multiple locations simultaneously across the radar field of view. Electron density profiles and collision frequencies (usually obtained from neutral models) are required to calculate conductivity, making these observations well suited for this project. SRI will also investigate how conductivity impacts the formation of plasma irregularities on a variety of scales. The high-latitude ionosphere is a highly structured and dynamic environment characterized by gradients, fast flows, and plasma irregularities.This structuring is ubiquitous and quasi-random, driven by global coupling and local plasma instability mechanisms, which makes it extremely challenging to predict when, where, and how it will impact the ionosphere. One factorthat influences these plasma structures is known as E-region shorting#the phenomenon by which potential differences in the F-regionionosphere where plasma does not move easily across magnetic field lines are #shorted out# through a conductive E-region. Because potential differences are associated with electric fields that drive many plasma instability mechanisms, E-region shorting serves to suppress the production of plasma irregularities. In addition to cataloging ionospheric conductivity, SRI will use direct and indirect measurements of plasma irregularities from a variety of instruments (Swarm high-rate in situ density, GNSS scintillation, and SuperDARN HF backscatter) to evaluate where E-region shorting appears to suppress irregularity development.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 08, 2024
- Source ID
- N000142412411
Entities
People
- Leslie Lamarche
Organizations
- Office of Naval Research
- SRI International
- United States Navy