Joshua Semeter

Spacecraft-to-Earth radio occultation (RO) experiments are a powerful tool for probing planetary atmospheres and ionospheres. However, standard processing typically requires manual intervention and assumes spherical symmetry. This assumption is rarely tested, and its impact on retrieved electron density profiles is not often quantified. Here we present Processing Radio Occultations System for Examining and Reconstructing Planetary Ionised and Neutral Atmospheres (PROSERPINA), a fully automated Python pipeline designed to retrieve electron density profiles from one-way radio occultation observations at Mars. The pipeline also introduces Forward–Backward Ionospheric Density Estimation System (FIDES), a module that quantifies the bias introduced by the spherical-symmetry assumption in Abel inversion. FIDES generates synthetic two-dimensional ionospheres anchored to the retrieved Abel peak and analyzes the difference between FIDES and Abel results. This difference is decomposed into amplitude, peak-altitude, and width components, producing a structured model-error covariance for each profile. The Abel-retrieved profile remains the primary estimate. The reported 95% credible intervals incorporate contributions from thermal noise, uncertainty in the baseline slope, and the model uncertainty derived from FIDES. We validate PROSERPINA using Mars Global Surveyor (MGS) electron density profiles archived and processed independently in the NASA Planetary Data System and apply it to 100 previously unprocessed MGS profiles, of which 20 are fully shown here. Across these cases, the uncertainty associated with the spherical-symmetry assumption dominates over baseline-slope uncertainty and thermal noise for high solar zenith angle dayside M2 peaks, contributing a median uncertainty of about 30% of the peak density.

This paper presents a major update to the PyIRI model, a fully vectorized Python implementation of the International Reference Ionosphere (IRI). The update reformulates the IRI core coefficients using spherical harmonics in Quasi‐Dipole (QD) latitude and Magnetic Local Time coordinates, replacing the legacy geographic‐coordinate‐based basis functions of the CCIR (Consultative Committee on International Radio) and URSI (International Union of Radio Science) models of the fo F2 critical plasma frequency parameter. The resulting coefficients remain valid over decadal timescales, with re‐derivation recommended every 5 years to account for magnetic pole drift. This new formulation removes the dependence on the modified dip angle, enabling a more transparent and physically interpretable representation of ionospheric climatology. Diurnal variability is expressed through real Fourier series, with the optimal number of spatial and temporal coefficients determined via reconstruction error analysis. The coefficients are stored in standardized NetCDF format and validated against IRI‐2020. Artificial small‐scale oscillations present in the original IRI climatology are substantially reduced in the new formulation, leading to an ionosphere more consistent with the SAMI physics‐based model. The updated PyIRI model also includes previously unavailable IRI parameters, such as the SHU‐2015 and AMTB2013 options for hm F2, and the B0 and B1 F2‐layer thickness and shape parameters. Spherical harmonic coefficients are extracted identically across the fo F2 CCIR, fo F2 URSI, hm F2 SHU‐2015, hm F2 AMTB2013, M(3000)F2, and foEs parameters.

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 investigates the impact of high‐latitude ionospheric irregularities on global positioning system (GPS) position accuracy during the 10–11 May 2024 geomagnetic storm. Using data from ground‐based GPS receivers and an all‐sky camera in Antarctica, we examined evolution of GPS vertical total electron content, phase fluctuations, and precise point positioning (PPP) errors. Results reveal that auroral precipitation associated with the coronal mass ejection shock induced significant GPS phase fluctuations and positioning errors in the dayside cusp region. Tongues of ionization (TOIs) had the largest and most sustained impact on signal disruptions and degraded position accuracy, with a peak position error reaching 28 m. Furthermore, dawnside auroral activity during the substorms and poleward boundary intensifications (PBIs) caused localized disturbances in the auroral oval. Despite sufficient satellite visibility, these irregularities significantly compromised GPS positioning performance.

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.

This study investigates impacts of the May 2024 superstorm on the mid‐latitude Global Positioning System (GPS) scintillation and position errors. Using 1‐Hz GPS receiver data, we identified position errors in PPP mode reaching up to 70 m in the Central United States during the storm main phase on May 10. The PPK solution becomes unstable following the arrival of storm and lasted till the recovery phase, coinciding with reported GPS outages of farming equipment. The large position errors were attributed to strong scintillation and carrier phase cycle slips around the equatorward boundary of the ionosphere trough, where large total electron content (TEC) gradients and irregularities were present. In the Southwestern United States, position errors of 10–20 m were associated with the storm‐enhanced density and equatorial ionization anomaly. Scintillation and cycle slips in this region were minor, and bending of the GPS signal paths (refractive effect) is suggested to cause the position errors. PPP outages were also associated with sudden changes in the geometric distributions of available GPS satellites used in position calculations. On May 11, energetic particle precipitation during substorms led to abrupt jumps in TEC and scintillation, resulting in rapidly evolving position errors of up to 10 m. These findings highlight the critical role of storm‐time plasma transport, precipitation, and irregularity formation in degrading GPS performance. The study underscores the need for accurate ionospheric state specification, improved signal processing technique, real‐time ionospheric corrections, and optimized satellite selection algorithms, to enhance navigation resilience during severe space weather events.

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.

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.

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 total electron content (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 descended 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.