skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.
Attention:The NSF Public Access Repository (PAR) system and access will be unavailable from 11:00 PM ET on Thursday, May 14 until 2:00 AM ET on Friday, May 15 due to maintenance. We apologize for the inconvenience.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Model‐Based Investigation of Electron Precipitation‐Driven Density Structures and Their Effects on Auroral Scintillation
Title: Model‐Based Investigation of Electron Precipitation‐Driven Density Structures and Their Effects on Auroral Scintillation
Abstract Electron density irregularities in the ionosphere can give rise to scintillations, affecting radio wave phase and amplitude. While scintillations in the cusp and polar cap regions are commonly associated with mesoscale density inhomogeneities and/or shearing, the auroral regions exhibit a strong correlation between scintillation and density structures generated by electron precipitation (arcs). We aim to examine the impact of electron precipitation on the formation of scintillation‐producing density structures using a high‐resolution physics‐based plasma model, the “Geospace Environment Model of Ion‐Neutral Interactions,” coupled with a radio propagation model, the “Satellite‐beacon Ionospheric‐scintillation Global Model of the upper Atmosphere.” Specifically, we explore the effects of varying spatial and temporal characteristics of the precipitation, including electron total energy flux and their characteristic energies, obtained from the all‐sky‐imagers and Poker Flat Incoherent Scatter Radar observations, on auroral scintillation. To capture small‐scale structures, we incorporate a power‐law turbulence spectrum that induces short wavelength features sensitive to scintillation. Finally, we compare our simulated scintillation results with satellite‐observed scintillations, along with spectral comparisons.  more » « less
Award ID(s):
1907698 1848207
PAR ID:
10539341
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Publisher / Repository:
Journal of Geophysical Research
Date Published:
Journal Name:
Journal of Geophysical Research: Space Physics
Volume:
129
Issue:
7
ISSN:
2169-9380
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, Sensors)
    Electron density irregularities in the ionosphere modify the phase and amplitude of trans-ionospheric radio signals. We aim to characterize the spectral and morphological features of E- and F-region ionospheric irregularities likely to produce these fluctuations or “scintillations”. To characterize them, we use a three-dimensional radio wave propagation model—“Satellite-beacon Ionospheric scintillation Global Model of upper Atmosphere” (SIGMA), along with the scintillation measurements observed by a cluster of six Global Positioning System (GPS) receivers called Scintillation Auroral GPS Array (SAGA) at Poker Flat, AK. An inverse method is used to derive the parameters that describe the irregularities by estimating the best fit of model outputs to GPS observations. We analyze in detail one E-region and two F-region events during geomagnetically active times and determine the E- and F-region irregularity characteristics using two different spectral models as input to SIGMA. Our results from the spectral analysis show that the E-region irregularities are more elongated along the magnetic field lines with rod-shaped structures, while the F-region irregularities have wing-like structures with irregularities extending both along and across the magnetic field lines. We also found that the spectral index of the E-region event is less than the spectral index of the F-region events. Additionally, the spectral slope on the ground at higher frequencies is less than the spectral slope at irregularity height. This study describes distinctive morphological and spectral features of irregularities at E- and F-regions for a handful of cases performed using a full 3D propagation model coupled with GPS observations and inversion. 
    more » « less
  2. ; ; ; ; ; ; (, The Astrophysical Journal)
    Abstract To date, the search for radio technosignatures has focused on sky location as a primary discriminant between technosignature candidates and anthropogenic radio frequency interference (RFI). In this work, we investigate the possibility of searching for technosignatures by identifying the presence and nature of intensity scintillations arising from the turbulent, ionized plasma of the interstellar medium. Past works have detailed how interstellar scattering can both enhance and diminish the detectability of narrowband radio signals. We use the NE2001 Galactic free electron density model to estimate scintillation timescales to which narrowband signal searches would be sensitive, and discuss ways in which we might practically detect strong intensity scintillations in detected signals. We further analyze the RFI environment of the Robert C. Byrd Green Bank Telescope with the proposed methodology and comment on the feasibility of using scintillation as a filter for technosignature candidates. 
    more » « less
  3. (, Radio Science)
    The utilization of the global navigation satellite systems (GNSS) services in both military and civilian applications as well as for scientific investigation has grown exponentially. However, the increasing reliance on GNSS applications has raised concerns about potential risks from intentional radio frequency interference (RFI) transmitters. RFI significantly affects GNSS's environmental monitoring capabilities by inflating the scintillation index and misleading the scientific community with scintillation indices not attributable to ionospheric dynamic events. Consequently, the existing climatological distribution of GNSS scintillations may require careful reevaluation, as it may not adequately filter out RFI induced scintillations. Thus, characterizing the global RFI occurrence regions and developing real‐time detection capabilities to mitigate its effects is critically important. Leveraging GNSS measurements from ground stations and six COSMIC‐2 satellite constellations, we have developed a technique to detect RFI events and identify RFI active regions. Additionally, for the first time, we have implemented techniques that differentiate RFI associated scintillations from scintillations caused by ionospheric turbulence. 
    more » « less
  4. ; ; ; ; ; ; (, Journal of Geophysical Research: Space Physics)
    Abstract We report the first simultaneous observations of total electron content (TEC), radio signal scintillation, and precise point positioning (PPP) variation associated with Strong Thermal Emission Velocity Enhancement (STEVE) emissions during a 26 March 2008 storm‐time substorm. Despite that the mid‐latitude trough TEC decreases during the substorm overall, interestingly, we found an unexpected TEC enhancement (by ∼2 TECU) during STEVE. Enhancement of vertical TEC and phase scintillation was highly localized to STEVE within a thin latitudinal band of 1°. As STEVE shifted equatorward, TEC enhancement was found at and slightly poleward of the optical emission. PPP exhibited enhanced variation across a 3° latitudinal range around STEVE and indicated increased GNSS positioning error. We suggest that TEC enhancement during STEVE creates local TEC structures in the ionosphere that degrade Global Navigation Satellite Systems (GNSS) signals and PPP performance. The TEC enhancement may be created by particle precipitation, Pedersen drift across STEVE, neutral wind, or plasma instability. 
    more » « less
  5. ; ; ; ; (, Journal of Astronomy and Space Sciences)
    This study investigates high-latitude ionospheric mesoscale irregularities associated with energetic particle precipitation and magnetosphere-ionosphere-thermosphere coupling processes within the auroral oval using ground-based Global Navigation Satellite Systems (GNSS) total electron content (TEC) measurements. This scale size is much larger than those associated with GNSS scintillations, which range from sub-kilometers (small scales) to > 10 km (large scales). Analyzing 15 yr of data from 2010 to 2024, we characterize, for the first time, the climatology of enhanced intensity of ionospheric mesoscale irregularities at high latitudes. The observed intensity of irregularities in GNSS TEC fluctuations can serve as a proxy for the dynamic behavior of the auroral oval which varies with magnetic local time, longitude, latitude, season, solar activity cycle, geomagnetic disturbances, and hemisphere. The spatial distribution of the irregularity is oval-shaped and therefore this pattern is named as “irregularity oval”; the morphology of the irregularity oval is generally aligned well with the known variations of auroral oval established by using other technologies. While the primary goal has been to document systematically these irregularity long-term observations, future work will focus on the development of a novel GNSS TEC-based “irregularity oval” model. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email