Michael Hirsch

This study explores the potential of dual‐frequency smartphones as accessible tools for citizen science in ionospheric research. While prior work by Smith et al. (2024, https://doi.org/10.1038/s41586‐024‐08072‐x ) demonstrated global ionospheric monitoring using aggregated pseudorange Total Electron Content (TEC) data from millions of Android devices, this approach faces limitations: restricted data access due to privacy concerns, uncontrolled signal degradation from passive collection, severe multipath interference from phone antennas, and an inability to utilize higher‐accuracy carrier phase TEC due to Android duty cycling. We propose an orthogonal approach focused on active, localized carrier phase TEC collection from individual smartphones. We demonstrate the capability of smartphones as standalone Global Navigation Satellite System (GNSS) receivers under quiet ionospheric conditions, during a total solar eclipse (large‐scale phenomenon), and during auroral substorms (small‐scale phenomena). Our method only requires an Android dual‐frequency phone with duty cycling disabled, a clear field of view, and a willing participant. This work establishes a practical foundation for future privacy‐preserving citizen science campaigns, highlighting their significant potential to advance ionospheric science.

This study explores the potential of dual-frequency smartphones as accessible tools for citizen science in ionospheric research.While prior work by Smith et al. (2024) demonstrated global ionospheric monitoring using aggregated pseudorange Total Electron Content (TEC) data from millions of Android devices, this approach faces limitations: restricted data access due to privacy concerns, uncontrolled signal degradation from passive collection, severe multipath interference from phone antennas, and an inability to utilize higher-accuracy carrier phase TEC due to Android duty cycling. We propose an orthogonal approach focused on active, localized carrier phase TEC collection from individual smartphones. We demonstrate the capability of smartphones as standalone Global Navigation Satellite System (GNSS) receivers under quiet ionospheric conditions, during a total solar eclipse (large-scale phenomenon), and during auroral substorms (small-scale phenomena). Our method only requires an Android dual-frequency phone with duty cycling disabled, a clear field of view, and a willing participant. This work establishes a practical foundation for future privacy-preserving citizen science campaigns, highlighting their significant potential to advance ionospheric science.

Subauroral Ion Drift (SAID) channels and Strong Thermal Emission Velocity Enhancement (STEVE) phenomena are distinct features of ionospheric dynamics that are accompanied by strong electric field forcing that is related to plasma turbulence in the E‐region. This study investigates the role of the Farley‐Buneman Instability (FBI) in modulating SAID and related phenomena, focusing on its impact on the evolution of extreme SAID channels. Using the Geospace Environment Model of Ion‐Neutral Interactions (GEMINI), we incorporate macroscopic effects of FBI‐induced turbulence in the form of anomalous electron heating and non‐linear current density. Results demonstrate that FBI‐induced turbulence produces a significant dampening effect on SAID channel velocity growth by increasing E‐region conductance and density. This effect alters the electric field dynamics and moderates the extreme velocities characteristic of SAID channels. These findings underscore the critical role of including turbulence‐driven processes in predictive models, advancing our understanding of magnetosphere‐ionosphere coupling and space weather phenomena. This work is understood as missing physics that would increase the dampening effect, such as inelastic collisions and excitation of resonant cross‐sections in electron neutral collisions, yet introduces itself as a starting point and an appeal to further improve.

Subauroral Ion Drift (SAID) channels and Strong Thermal Emission Velocity Enhancement (STEVE) phenomena are distinct features of ionospheric dynamics that are accompanied by strong electric field forcing that is related to plasma turbulence in the E-region. This study investigates the role of the Farley-Buneman Instability (FBI) in modulating SAID and related phenomena, focusing on its impact on the evolution of extreme SAID channels. Using the Geospace Environment Model of Ion-Neutral Interactions (GEMINI), we incorporate macroscopic effects of FBI-induced turbulence in the form of anomalous electron heating and non-linear current density. Results demonstrate that FBI-induced turbulence produces a significant dampening effect on SAID channel velocity growth by increasing E-region conductance and density. This effect alters the electric field dynamics and moderates the extreme velocities characteristic of SAID channels. These findings underscore the critical role of including turbulence-driven processes in predictive models, advancing our understanding of magnetosphere-ionosphere coupling and space weather phenomena. This work is understood as missing physics that would increase the dampening effect, suck as inelastic collisions and excitation of resonant cross-sections in electron neutral collisions, yet introduces itself as a starting point and a plead to further improve.

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.

Space‐based observations of the signatures associated with STEVE show how this phenomenon might be closely related to an extreme version of a SAID channel. Measurements show high velocities (>4 km/s), high temperatures (>4,000 K), and very large current density drivers (up to 1 μA/m²). This phenomena happens in a small range of latitudes, less than a degree, but with a large longitudinal span. In this study, we utilize the GEMINI model to simulate an extreme SAID/STEVE. We assume a FAC density coming from the magnetosphere as the main driver, allowing all other parameters to adjust accordingly. We have two main objectives with this work: show how an extreme SAID can have velocity values comparable or larger than the ones measured under STEVE, and to display the limitations and missing physics that arise due to the extreme values of temperature and velocity. Changes had to be made to GEMINI due to the extreme conditions, particularly some neutral‐collision frequencies. The importance of the temperature threshold at which some collision frequencies go outside their respective bounds, as well as significance of the energies that would cause inelastic collisions and impact ionization are displayed and discussed. We illustrate complex structures and behaviors, emphasizing the importance of 3D simulations in capturing these phenomena. Longitudinal structure is emphasized, as the channel develops differently depending on MLT. However, these simulations should be viewed as approximations due to the limited observations available to constrain the model inputs and the assumptions made to achieve sensible results.

Space-based observations of the signatures associated with STEVE show how this phenomenon might be closely related to an extreme version of a SAID channel. Measurements show high velocities ($>$4km/s), high temperatures ($>$4,000 K), and very large current density drivers (up to 1$\mu$A/m$^2$). This phenomena happens in a small range of latitudes, less than a degree, but with a large longitudinal span. In this study, we utilize the GEMINI model to simulate an extreme SAID/STEVE. We assume a FAC density coming from the magnetosphere as the main driver, allowing all other parameters to adjust accordingly. We have two main objectives with this work: show how an extreme SAID can have velocity values comparable or larger than the ones measured under STEVE, and to display the limitations and missing physics that arise due to the extreme values of temperature and velocity. Changes had to be made to GEMINI due to the extreme conditions, particularly some neutral-collision frequencies. The importance of the temperature threshold at which some collision frequencies go outside their respective bounds, as well as significance of the energies that would cause inelastic collisions and impact ionization are displayed and discussed. We illustrate complex structures and behaviors, emphasizing the importance of 3D simulations in capturing these phenomena. Longitudinal structure is emphasized, as the channel develops differently depending on MLT. However, these simulations should be viewed as approximations due to the limited observations available to constrain the model inputs and the assumptions made to achieve sensible results.

Whitepaper #445 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: space weather applications; basic research. Additional topics: space weather research/applications/operations pipeline; planetary ionospheres / upper atmospheres; system […]

The main ionospheric trough (MIT) is a salient density feature in the mid‐latitude ionosphere and characterizing its structure is important for understanding Global Positioning System and HF signal propagation, and identifying geospace phenomena such as the plasmapause boundary layer. While a number of previous studies have statistically investigated the properties of the MIT utilizing low‐altitude satellite observations, they have been limited to latitudinal cross sections, and have not considered the inherent two‐dimensional structure of the MIT. In this work, we develop a regularized inversion method for identifying the two dimensional structure of the MIT in Total Electron Content maps. Because no ground truth labels exist for the MIT, we extensively characterize the behavior of the algorithm by comparing it to the method developed by Aa, Zou, et al. (2020, doi:https://doi.org/10.1029/2019JA027583). We show that statistics computed on the resulting labels are robust to our choice of algorithm parameters and that we are able to match the results of Aa, Zou, et al. (2020, doi:https://doi.org/10.1029/2019JA027583) with a particular selection of the parameters. In addition to enabling fundamentally different studies, our MIT labels are able to provide statistical MIT properties with higher resolution. Code to reproduce our data set is provided in a GitHub repository: https://github.com/gregstarr/trough.

A community of developers has formed to modernize the Fortran ecosystem. In this article, we describe the high-level features of Fortran that continue to make it a good choice for scientists and engineers in the 21st century. Ongoing efforts include the development of a Fortran standard library and package manager, the fostering of a friendly and welcoming online community, improved compiler support, and language feature development. The lessons learned are common across contemporary programming languages and help reduce the learning curve and increase adoption of Fortran.