Abstract 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 foF2 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 hmF2, and the B0 and B1 F2‐layer thickness and shape parameters. Spherical harmonic coefficients are extracted identically across the foF2 CCIR, foF2 URSI, hmF2 SHU‐2015, hmF2 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.

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.

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. A physics-based plasma model and a radio propagation model are used to examine the effects of precipitation on auroral scintillation Precipitation fluxes with higher energy, a turbulent noise spectrum, and a faster-moving arc intensify scintillation The presence of small-scale precipitation amplifies both phase and amplitude scintillations

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 similar to 2 TECU) during STEVE. Enhancement of vertical TEC and phase scintillation was highly localized to STEVE within a thin latitudinal band of 1 degrees. As STEVE shifted equatorward, TEC enhancement was found at and slightly poleward of the optical emission. PPP exhibited enhanced variation across a 3 degrees 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.

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.

We examined evolution of Global Positioning System (GPS) scintillation during a substorm in the nightside high latitude ionosphere, using 1‐s phase and amplitude scintillation indices from the Canadian High Arctic Ionospheric Network (CHAIN) network. The traditional 1‐min scintillation indices showed that the phase scintillation was dominant, while the amplitude scintillation was weak. However, the 1‐s amplitude scintillation occurred more often in association with major auroral structures (polar cap arc, growth phase arc, onset arc, poleward expanding arc, poleward boundary intensification, and diffuse aurora) that were detected by the THEMIS all‐sky imagers (ASIs). The 1‐min index missed much of the amplitude fluctuations because they only lasted ∼10 s near a local peak or at the gradients of the auroral structures. The 1‐s phase scintillation was concurrent with the amplitude scintillation but was much weaker than the 1‐min phase scintillation. The frequency spectral analysis showed that the spectral power above ∼1 Hz was diffractive and below ∼1 Hz was refractive. We suggest that the amplitude scintillation in the high‐latitude ionosphere is much more common than previously considered, and that a short time window of the order of 1 s should be used to detect the scintillation. The 1‐min phase scintillation index is largely influenced by refractive effects due to total electron content (TEC) variations, and the spectral power below ∼1 Hz should be removed to identify diffractive scintillation.

Abstract 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.

Evolution of large‐scale and fine‐scale plasmaspheric plume density structures was examined using space‐ground coordinated observations of a plume during the 7–8 September 2015 storm. The large‐scale plasmaspheric plume density at Van Allen Probes A was roughly proportional to the total electron content (TEC) along the satellite footprint, indicating that TEC distribution represents the large‐scale plume density distribution in the magnetosphere. The plasmaspheric plume contained fine‐scale density structures and subauroral polarization streams (SAPS) velocity fluctuations. High‐resolution TEC data support the interpretation that the fine‐scale plume structures were blobs with ∼300 km size and ∼500–800 m/s in the ionosphere (∼3,000 km size and ∼5–8 km/s speed in the magnetosphere), emerging at the plume base and drifting to the plume. The short‐baseline Global Navigation Satellite System receivers detected smaller‐scale (∼10 km in the ionosphere, ∼100 km in the magnetosphere) TEC gradients and their sunward drift. Fine‐scale density structures were associated with enhanced phase scintillation index. Velocity fluctuations were found to be spatial structures of fine‐scale SAPS flows that drifted sunward with density irregularities down to ∼10 s of meter‐scale. Fine‐scale density structures followed a power law with a slope of ∼−5/3, and smaller‐scale density structures developed slower than the larger‐scale structures. We suggest that turbulent SAPS flows created fine‐scale density structures and their cascading to smaller scales. We also found that the plume fine‐scale density structures were associated with whistler‐mode intensity modulation, and localized electron precipitation in the plume. Structured precipitation in the plume may contribute to ionospheric heating, SAPS velocity reduction, and conductance enhancements.

The impacts of solar eclipses on the ionosphere‐thermosphere system particularly the composition, density, and transport are studied using numerical simulation and subsequent model‐data comparison. We introduce a newly developed model of a solar eclipse mask (shadow) at extreme ultraviolet (EUV) wavelengths—PyEclipse—that computes the corresponding shadowing as a function of space, time, and wavelength of the input solar image. The current model includes interfaces for Solar Dynamics Observatory and Geostationary Operational Environmental Satellites EUV telescopes providing solar images at nine different wavelengths. We show the significance of the EUV eclipse shadow spatial variability and that it varies significantly with wavelength owing to the highly variable solar coronal emissions. We demonstrate geometrical differences between the EUV eclipse shadow compared to a geometrically symmetric simplification revealing changes in occultation vary ±20%. The EUV eclipse mask is validated with in situ solar flux measurements by the PRoject for Onboard Autonomy 2/Large Yield Radiometer instrument suite showing the model captures the morphology and amplitudes of transient variability while the modeled gradients are slower. The effects of spatially EUV eclipse masks are investigated with Global Ionosphere Thermosphere Model for the 21 August 2017 eclipse. The results reveal that the modeled EUV eclipse mask, in comparison with the geometrically symmetric approximation, causes changes in the Total Electron Content in order of ±20%, 5%–20% in F‐region plasma drift, and 20%–30% in F‐region neutral winds.

Mesoscale high‐latitude electric fields are known to deposit energy into the ionospheric and thermospheric system, yet the energy deposition process is not fully understood. We conduct a case study to quantify the energy deposition from mesoscale high‐latitude electric fields to the thermosphere. For the investigation, we obtain the high‐latitude electric field with mesoscale variabilities from Poker Flat Incoherent Scatter Radar measurements during a moderate geomagnetic storm, providing the driver for the Global Ionosphere and Thermosphere Model (GITM) via the High‐latitude Input for Mesoscale Electrodynamics framework. The HIME‐GITM simulation is compared with GITM simulations driven by the large‐scale electric field from the Weimer model. Our modeling results indicate that the mesoscale electric field modifies the thermospheric energy budget primarily through enhancing the Joule heating. Specifically, in the local high‐latitude region of interest, the mesoscale electric field enhances the Joule heating by up to five times. The resulting neutral temperature enhancement can reach up to 50 K above 200 km altitude. Significant increase in the neutral density above 250 km altitude and in the neutral wind speed are found in the local region as well, lagging a few minutes after the Joule heating enhancement. We demonstrate that the energy deposited by the mesoscale electric field transfers primarily to the gravitational potential energy in the thermosphere.

This study exploits the volumetric sampling capabilities of the Resolute Bay Incoherent Scatter Radar (RISR‐N) in collaboration with all‐sky imagery and in situ measurements to examine the interplay between cold plasma transport and auroral precipitation during a high‐latitude lobe reconnection event on the dawn side. Solar wind IMF preceding the event was characterized by an impulsive negative excursion in Bz embedded within a period of Bz > 0 and By < 0. The combined effects of transport and magnetic stress release associated with a high‐latitude reconnection pulse drove a co‐mingling between patches and soft electron precipitation, creating common regions of elevated electron density and temperature. Vertical ionospheric profiles extracted in the rest frame of the drifting patch showed a contemporaneous increase in Te above 200 km and Ne below 250 km while at the same time showing only a small impact in Ne near the F‐region peak. The observations suggest a new mechanism for creating a “hot patch” wherein the density enhancement is not generated by the precipitation but is warmed by it. The physics‐based GEMINI model was used to explore the response to the observed precipitation as a function of altitude and time. Model results suggest that a correlated enhancement in Ne and Te at DMSP altitudes (∼800 km), that is, hot patch, can be produced by auroral heating and upward diffusion, irrespective of lower altitude density structure. The study highlights the need for densely distributed observations in space and time for understanding both mesoscale and small‐scale ionospheric dynamics in regions subject to complex forcing.

Using the University Navstar Consortium (UNAVCO) Global Positioning System (GPS) receiver network in North America, we present 2‐D distributions of GPS radio signal scintillation in the mid‐latitude ionosphere during the 7–8 September 2017 storm. The mid‐latitude ionosphere showed a variety of density structures such as the storm enhanced density (SED) base and plume, main trough, secondary plume, and secondary trough during the storm main and early recovery phases. Enhanced phase and amplitude scintillation indices were observed at the density gradients of those structures. SuperDARN radar echoes were also enhanced at the density gradients. The collocation of the scintillation and HF radar echoes indicates that density irregularities developed across a wide range of wavelengths (tens of meters to tens of kilometers) in the mid‐latitude density structures. The density gradients and irregularities were also detected by Swarm and DMSP as in‐situ density structures that disturbed the GPS signals. The irregularities were a substantial fraction (∼10%–50%) of the background density. The density irregularity had a power law spectrum with slope of ∼ −1.8, suggesting that gradient drift instability (GDI) contributed to turbulence formation. Both high‐latitude and low‐latitude processes likely contributed to forming the mid‐latitude density structures, and the mid‐latitude scintillation occurred at the interface of high‐latitude and low‐latitude forcing.

A Correction to this paper has been published: 10.1007/s11214-021-00821-y

Earth and Space Science Open Archive This is a preprint and has not been peer reviewed. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]An EUV Model of Solar Eclipses using SDO-AIA Images and the Impacts on Ionosphere-Thermosphere SystemAuthorsSebastijanMrakiDJoshuaSemeteriDYukitoshiNishimuraMarcHairstoniDQingyuZhuiDYueDengSee all authors Sebastijan MrakiDCorresponding Author• Submitting AuthorBoston UniversityiDhttps://orcid.org/0000-0002-3925-760Xview email addressThe email was not providedcopy email addressJoshua SemeteriDBoston UniviDhttps://orcid.org/0000-0001-7442-6205view email addressThe email was not providedcopy email addressYukitoshi NishimuraUniversity of California Los Angelesview email addressThe email was not providedcopy email addressMarc HairstoniDUniv of Texas at DallasiDhttps://orcid.org/0000-0003-4524-4837view email addressThe email was not providedcopy email addressQingyu ZhuiDUniversity of Texas at ArlingtoniDhttps://orcid.org/0000-0002-4003-4104view email addressThe email was not providedcopy email addressYue DengUniversity of Texas Arlingtonview email addressThe email was not providedcopy email address

We present results of the NASA Living With a Star Institute 2019: "Space Weather Impacts TEC and scintillations at Mid-Latitudes." We analyzed available ground-based observations of GPS scintillation events in the context of geophysical drivers associated with ionospheric space weather. We leverage geodetic receivers with a 1-Hz temporal resolution to drive proxy scintillation indices. We discuss observability limits of the 1-Hz receivers and their utility as a space weather diagnostic. The GPS receivers cover the American longitude sector, spanning from Panama to Canada in latitudes. We surveyed 8 years of available data between 2012 and 2020 and found 9 events during which a portion of the receiver network observed amplitude scintillations at magnetic mid-latitudes. All events occurred during geomagnetic storms. The storm's Dst ranged between -204 nT and -51 nT, with a median of -131 nT, and median Kp 7-. We discuss some individual events in more detail.

Objective: Early identification of individuals who are at risk for suicide is crucial in supporting suicide prevention. Machine learning is emerging as a promising approach to support this objective. Machine learning is broadly defined as a set of mathematical models and computational algorithms designed to automatically learn complex patterns between predictors and outcomes from example data, without being explicitly programmed to do so. The model's performance continuously improves over time by learning from newly available data. Method: This concept paper explores how machine learning approaches applied to healthcare data obtained from electronic health records, including billing and claims data, can advance our ability to accurately predict future suicidal behavior. Results: We provide a general overview of machine learning concepts, summarize exemplar studies, describe continued challenges, and propose innovative research directions. Conclusion: Machine learning has potential for improving estimation of suicide risk, yet important challenges and opportunities remain. Further research can focus on incorporating evolving methods for addressing data imbalances, understanding factors that affect generalizability across samples and healthcare systems, expanding the richness of the data, leveraging newer machine learning approaches, and developing automatic learning systems.

Abstract We report on an extreme ionospheric plasma density enhancement and Global Positioning System (GPS) scintillation at dawn, observed within the expanding equatorial ionization anomaly (EIA). The total electron content (TEC) in central America reached 50 TECu at sunrise, the value almost twice as high as the normal afternoon peak. The enhanced EIA expanded poleward and westward from just below 20° magnetic latitude (MLAT) to beyond 30° MLAT at sunrise. The chief ramification of the enhanced EIA was strong GPS scintillation which was observed poleward of 30° northern MLAT and lasted until 8:00 local time. In total, the amplitude scintillation and phase fluctuations lasted for ∼5 h at latitudes north of 20°MLAT in central America.

Small-scale dynamic auroras have spatial scales of a few km or less, and temporal scales of a few seconds or less, which visualize the complex interplay among charged particles, Alfvén waves, and plasma instabilities working in the magnetosphere-ionosphere coupled regions. We summarize the observed properties of flickering auroras, vortex motions, and filamentary structures. We also summarize the development of fundamental theories, such as dispersive Alfvén waves (DAWs), plasma instabilities in the auroral acceleration region, ionospheric feedback instabilities (IFI), and the ionospheric Alfvén resonator (IAR).