ANGEO - recent papers

Next-generation Ionospheric Model for Operations – validation and demonstration for space weather and research

Thu, 23 Apr 2026 18:06:28 +0200

Next-generation Ionospheric Model for Operations – validation and demonstration for space weather and research
Angeline G. Burrell, Sarah McDonald, Dustin Hickey, Meghan Burleigh, Eliana Nossa, Christopher A. Metzler, Manbharat Dhadly, Jennifer L. Tate, and Ellen J. Wagner
Ann. Geophys., 44, 303–329, https://doi.org/10.5194/angeo-44-303-2026, 2026
The Next-generation Ionospheric Model for Operations (NIMO) is a space weather model developed to provide historic, current, and forecasted information about the density of the ionosphere. This article discusses how NIMO is configured, demonstrates potential use cases for the research community, and validates historic runs using a new suite of metrics designed to allow repeatable, quantitative, model-independent evaluations against observations that may be adopted by other ionospheric models.

Effect of a non-hydrostatic core-mantle boundary on the nutations and Length-of-day of Mars

Thu, 23 Apr 2026 18:06:28 +0200

Effect of a non-hydrostatic core-mantle boundary on the nutations and Length-of-day of Mars
Marta Folgueira López, Véronique Dehant, Mihaela Puica, and Tim Van Hoolst
Ann. Geophys., 44, 287–301, https://doi.org/10.5194/angeo-44-287-2026, 2026
Mantle mass anomalies can deform Mars’ core–mantle boundary (CMB). Unlike Earth’s mainly degree 2–order 2 pattern, Mars’ Tharsis and crustal dichotomy cause multiple deformation types. Here, researchers studied how dynamic CMB topography affects Mars’ nutations and length-of-day (LOD). They found the main (though tiny) effect on nutations comes from degree 2–order 2, while LOD changes are too small to detect.

Subauroral contamination in POES/Metop TED channels

Thu, 09 Apr 2026 18:06:28 +0200

Subauroral contamination in POES/Metop TED channels
Jan Maik Wissing, Olesya Yakovchuk, Stefan Bender, and Christina Arras
Ann. Geophys., 44, 263–285, https://doi.org/10.5194/angeo-44-263-2026, 2026
We investigate the subauroral flux maximum (at 60° N/S geomagetic) observed in low-energy particle channels. Two independent atmospheric impact measurements refute the subauroral flux under low Kp, pointing to instrumental contamination, likely from energetic electrons. We propose correction methods to mitigate contamination, ensuring accurate ionization estimates. Without correction, subauroral flux overestimates thermospheric ionization, underscoring the need for data refinement.

Benchmarking the Swedish Power Grid Against a 1-in-100-Year Geoelectric Field Scenario

Wed, 08 Apr 2026 18:06:28 +0200

Benchmarking the Swedish Power Grid Against a 1-in-100-Year Geoelectric Field Scenario
Vanina Lanabere, Andrew P. Dimmock, Sven Molenkamp Venholen, Alice V. L. Wallner, Andreas Johlander, Lisa Rosenqvist, and Johan Setréus
Ann. Geophys., 44, 245–261, https://doi.org/10.5194/angeo-44-245-2026, 2026
The goal of this study was to explore how a once-in-a-century geoelectric field event could affect the Swedish power grid by combining past storm data with a simplified model of the power grid. We identified regions that may be at higher risk and estimated how many power lines could be exposed to large voltages. These insights reveal vulnerable areas and provide a foundation for strengthening preparedness against rare, high-impact events.

Mapping transition region flows to the ionosphere in a global hybrid-Vlasov simulation

Fri, 27 Mar 2026 18:06:28 +0100

Mapping transition region flows to the ionosphere in a global hybrid-Vlasov simulation
Venla Koikkalainen, Maxime Grandin, Emilia Kilpua, Abiyot Workayehu, Ivan Zaitsev, Liisa Juusola, Shi Tao, Markku Alho, Lauri Pänkäläinen, Giulia Cozzani, Konstantinos Horaites, Jonas Suni, Yann Pfau-Kempf, Urs Ganse, and Minna Palmroth
Ann. Geophys., 44, 227–243, https://doi.org/10.5194/angeo-44-227-2026, 2026
We use a numerical simulation to study phenomena that occur between the Earth’s dipolar magnetic field and the nightside of near-Earth space. We observe the formation of large-scale vortex flows with scales of several Earth radii. On the ionospheric grid of the simulation we find that the field-aligned currents formed in the simulation reflect the vortex flow in the transition region. The main finding is that the vortex flow is a result of a combination of flow dynamics and a plasma instability.

The impact of electron precipitation on Earth's thermospheric NO production and the drag of LEO satellites

Mon, 16 Mar 2026 18:06:28 +0100

The impact of electron precipitation on Earth's thermospheric NO production and the drag of LEO satellites
Manuel Scherf, Sandro Krauss, Grigory Tsurikov, Andreas Strasser, Valery Shematovich, Dmitry Bisikalo, Helmut Lammer, Manuel Güdel, and Christian Möstl
Ann. Geophys., 44, 209–225, https://doi.org/10.5194/angeo-44-209-2026, 2026
We model the structure of the thermosphere for two space weather events that affected satellite orbits. Based on the Sun's irradiation, we simulate atmospheric density profiles and feed them into a model that calculates the influence of precipitating electrons on nitrogen oxide production in the atmosphere. Our results underscore the importance of considering both solar irradiance and particle precipitation to understand and predict space weather effects on the atmosphere and satellite orbits.

Variability and trend analysis of temperature and height in the upper troposphere and stratosphere region over the tropics (Réunion), by combining balloon-sonde and satellite measurements

Thu, 05 Mar 2026 18:06:28 +0100

Variability and trend analysis of temperature and height in the upper troposphere and stratosphere region over the tropics (Réunion), by combining balloon-sonde and satellite measurements
Gregori de Arruda Moreira, Hassan Bencherif, Tristan Millet, and Damaris Kirsch Pinheiro
Ann. Geophys., 44, 195–207, https://doi.org/10.5194/angeo-44-195-2026, 2026
Tropopause temperature and height serve as key indicators of anthropogenic climate change. However, monitoring their variability remains challenging due to the sparse distribution of observation stations, particularly in the Southern Hemisphere. To address this, we compared temperature profiles from three datasets—SHADOZ, COSMIC-1, and MERRA-2—to assess their similarities and differences and to develop a refined dataset for trend analysis.

ESA/JUICE encounters Earth/Moon in 2024: overview of the Moons And Jupiter Imaging Spectrometer (MAJIS) observations

Tue, 03 Mar 2026 18:06:28 +0100

ESA/JUICE encounters Earth/Moon in 2024: overview of the Moons And Jupiter Imaging Spectrometer (MAJIS) observations
François Poulet, Giuseppe Piccioni, Yves Langevin, Cydalise Dumesnil, Vincent Carlier, Benoit Seignovert, Marc Dexet, Leigh N. Fletcher, Cédric Leyrat, Francesca Altieri, John Carter, Emiliano D'Aversa, Maria De Sanctis, Davide Grassi, Sandrine Guerlet, Stéphane Le Mouélic, Alessandra Migliorini, Fabrizio Oliva, Clément Royer, Sébastien Rodriguez, Katrin Stephan, Federico Tosi, Francesca Zambon, Alberto Adriani, Gabriele Arnold, Jean-Pierre Bibring, Dominique Bockelée, Rosario Brunetto, Fabrizio Capaccioni, Cristian Carli, Thibault Cavalié, Miriam Cisneros González, Mauro Ciarnello, Simone De Angelis, Pierre Drossart, Gianrico Filacchione, Thierry Fouchet, Jean-Claude Gérard, Denis Grodent, Patrick Irwin, Sophie Jacquinod, Ozgur Karatekin, Emmanuel Lellouch, Nicolas Ligier, Nicolas Mangold, Magali Mebsout, Frédéric Merlin, Alessandro Morbidelli, Alessandro Mura, Andreas Nathues, Maria E. Palumbo, Cédric Pilorget, Olivier Poch, Eric Quirico, Andrea Raponi, Séverine Robert, Elias Roussos, Agustin Sanchez-Lavega, Bernard Schmitt, Giuseppe Sindoni, Marcel Snels, Roberto Sordini, Stefania Stefani, Giovanni Strazzulla, Tim Trent, Gabriel Tobie, Diego Turrini, Ann-Carine Vandaele, Mathieu Vincendon, Olivier Witasse, Claire Vallat, and Alessandro Moraino
Ann. Geophys., 44, 163–193, https://doi.org/10.5194/angeo-44-163-2026, 2026
During the double Lunar-Earth Gravitational Assist with the ESA/JUICE (Jupiter Icy Moons Explorer) spacecraft in August 2024, we acquired hyperspectral data cubes of both the Moon and Earth with the MAJIS (Moons And Jupiter Imaging Spectrometer) imaging spectrometer under challenging, real in-flight conditions. This allowed to characterize surface materials and thermophysical properties on the Moon, identify various cloud phases and gases in Earth's atmosphere, and thoroughly validate the performance of the instrument.

A source or a sink? How the altitude of particle precipitation influence high-latitude electrodynamics

Thu, 26 Feb 2026 18:06:28 +0100

A source or a sink? How the altitude of particle precipitation influence high-latitude electrodynamics
Magnus F. Ivarsen
Ann. Geophys., 44, 149–162, https://doi.org/10.5194/angeo-44-149-2026, 2026
When energetic particles rain into Earth’s lower ionosphere, they ionize the gas, creating a highly conductive base layer. Using a large database of observations from four orbiting space weather satellites, we demonstrate that this plasma foundation acts as a giant electrical short-circuit: it actively neutralizes the electric fields that would otherwise power plasma turbulence higher up. Without this conductive base to drain the energy, topside turbulence freely grows and persists.

Earth's magnetosheath: a comparison of plasma flow direction between models and observations

Wed, 25 Feb 2026 18:06:28 +0100

Earth's magnetosheath: a comparison of plasma flow direction between models and observations
Marek Vandas and Evgeny Romashets
Ann. Geophys., 44, 137–148, https://doi.org/10.5194/angeo-44-137-2026, 2026
Observations of the plasma flow direction in the Earth’s magnetosheath are compared with the help of three analytical magnetic-fieldmodels, namely Kobel and Flückiger (1994), Romashets and Vandas (2019), and Vandas and Romashets (2019), which all assume current-free fields in the magnetosheath. 47 magnetosheath passages by spacecraft are analyzed in detail and performance of the models are evaluated. It is concluded that the performances are comparable.

Effect of Ionospheric Variability on the Electron Energy Spectrum estimated from Incoherent Scatter Radar Measurements

Tue, 17 Feb 2026 18:06:28 +0100

Effect of Ionospheric Variability on the Electron Energy Spectrum estimated from Incoherent Scatter Radar Measurements
Oliver Stalder, Björn Gustavsson, and Ilkka Virtanen
Ann. Geophys., 44, 123–135, https://doi.org/10.5194/angeo-44-123-2026, 2026
The rapid changes in ion composition during auroral are dynamically modeled by integrating the coupled continuity equations for 15 ionospheric species. The effect of the ionospheric variation on the inversion of incoherent scatter radar (ISR) electron density profiles to differential energy spectra of precipitating electrons is studied. A systematic overestimation at high electron energies can be removed using a dynamic model. Comparisons are made with static and steady-state ionospheric models.

Data reduction of incoherent scatter plasma line parameters

Tue, 10 Feb 2026 18:06:28 +0100

Data reduction of incoherent scatter plasma line parameters
Mini Gupta and Patrick Guio
Ann. Geophys., 44, 109–122, https://doi.org/10.5194/angeo-44-109-2026, 2026
The ionosphere, formed by atmospheric ionization, contains free electrons and ions. Incoherent Scatter Radar probes it using high-frequency electromagnetic pulses, revealing ionospheric properties. Plasma lines, weak at thermal equilibrium, are enhanced and become detectable due to strong solar or auroral activity. This study develops methodologies to detect plasma lines, showing their strength decreases as the scattering radar beam is more oblique to the Earth's magnetic field.

Plasma density estimation from ionograms and geophysical parameters with deep learning

Tue, 03 Feb 2026 18:06:28 +0100

Plasma density estimation from ionograms and geophysical parameters with deep learning
Kian Sartipzadeh, Andreas Kvammen, Björn Gustavsson, Njål Gulbrandsen, Magnar G. Johnsen, Devin Huyghebaert, and Juha Vierinen
Ann. Geophys., 44, 85–107, https://doi.org/10.5194/angeo-44-85-2026, 2026
Knowledge of the charged environment in the upper atmosphere is essential for understanding space weather effects on satellites and radio communication. This environment is difficult to estimate at high latitudes, where aurora cause strong variability. We developed an artificial intelligence model to estimate this environment continuously. Our results show that the model provides reliable estimates even during auroral activity, improving monitoring of the polar upper atmosphere.

Observations of fragmented aurora-like emissions and picket fence on the poleward edge of the auroral oval

Tue, 03 Feb 2026 18:06:28 +0100

Observations of fragmented aurora-like emissions and picket fence on the poleward edge of the auroral oval
Sota Nanjo, Katie Herlingshaw, Tima Sergienko, Gaël Cessateur, Noora Partamies, Magnar G. Johnsen, Keisuke Hosokawa, Hervé Lamy, Yasunobu Ogawa, Antti Kero, Shin-ichiro Oyama, and Masatoshi Yamauchi
Ann. Geophys., 44, 63–84, https://doi.org/10.5194/angeo-44-63-2026, 2026
During the New Year’s Day storm of 2025, we observed rare auroral features: thin, short-lived green stripes and a “picket fence” near the poleward edge of the auroral oval. Using ground cameras and satellites, we found that the stripes sometimes appeared at widely separated longitudes at the same time and often tracked the motion of nearby red auroras. Some stripes were aligned with the magnetic field, while others were not, implying that multiple local processes contribute to their generation.

Solar wind driving of the auroral outflow during the 23–26 September 1998 storm

Fri, 30 Jan 2026 18:06:28 +0100

Solar wind driving of the auroral outflow during the 23–26 September 1998 storm
Kai Zhao, Lynn M. Kistler, Eric J. Lund, Niloufar Nowrouzi, Christopher G. Mouikis, and Naritoshi Kitamura
Ann. Geophys., 44, 47–61, https://doi.org/10.5194/angeo-44-47-2026, 2026
This study utilizes data from the FAST spacecraft orbiting over the auroral regions to investigate the temporal progression of energy inputs resulting from a Coronal Mass Ejection (CME) and how that energy increases the outflow of ionospheric plasma. We found that the various forms of energy are all enhanced during the initial phase of a storm, and the energy inputs are strongly correlated with the solar wind-magnetosphere coupling functions, especially in the dayside cusp region.

Statistical and temporal characteristics of sawtooth events

Wed, 14 Jan 2026 18:06:28 +0100

Statistical and temporal characteristics of sawtooth events
Connor C. DiMarco, Tuija I. Pulkkinen, and Michael G. Henderson
Ann. Geophys., 44, 35–46, https://doi.org/10.5194/angeo-44-35-2026, 2026
Sawtooth events are storm‑time surges of energetic particles with sharp rises and slow decays repeating every 2–4 h. From 2008–2016 they occur mostly in the solar cycle’s rising and declining phases and nearly always during geomagnetic storms. Geostationary data show near‑global, near‑simultaneous injections but strong magnetic changes only at midnight. This favors magnetotail reconnection and fast convection; sawteeth resemble a storm‑time substorm mode.

Time-dependent modeling of Alfvénic precipitation observed in the ionosphere

Mon, 12 Jan 2026 18:06:28 +0100

Time-dependent modeling of Alfvénic precipitation observed in the ionosphere
Etienne Gavazzi, Andres Spicher, Björn Gustavsson, James Clemmons, Robert Pfaff, and Douglas Rowland
Ann. Geophys., 44, 1–15, https://doi.org/10.5194/angeo-44-1-2026, 2026
Auroral precipitation refers to energetic particles that come down into the upper part of our atmosphere, the ionosphere. There, they collide with atoms and molecules and transfer some of their energy, causing aurora. The most rapid time-variation of this energy deposition and its consequences on the ionosphere are not fully understood. We show here that one can use a new model to study auroral precipitation on sub-second timescales and advance our understanding about small-scale dynamic aurora.

A comparison of modeled daytime E regions from E-PROBED and PyIRI with ionosonde observations

Mon, 12 Jan 2026 18:06:29 +0100

A comparison of modeled daytime E regions from E-PROBED and PyIRI with ionosonde observations
Daniel J. Emmons, Cornelius Csar Jude H. Salinas, Dong L. Wu, Nimalan Swarnalingam, Eugene V. Dao, Jorge L. Chau, Yosuke Yamazaki, Kyle E. Fitch, and Victoriya V. Forsythe
Ann. Geophys., 44, 17–34, https://doi.org/10.5194/angeo-44-17-2026, 2026
The E-region of the Earth’s ionosphere plays an important role in atmospheric energy balance and High Frequency radio propagation. In this paper, we compare predictions from two recently developed ionospheric models to observations by ionospheric sounders (ionosondes). Overall, the models show reasonable agreement with the observations. However, there are several areas for improvement in the models as well as questions about the accuracy of the automatically processed ionosonde dataset.

Globally- and hemispherically-integrated Joule heating rates during the 17 March 2015 geomagnetic storm, according to physics-based and empirical models

Wed, 17 Dec 2025 18:06:29 +0100

Globally- and hemispherically-integrated Joule heating rates during the 17 March 2015 geomagnetic storm, according to physics-based and empirical models
Stelios Tourgaidis, Dimitris Baloukidis, Panagiotis Pirnaris, Theodoros Sarris, Aaron Ridley, and Gang Lu
Ann. Geophys., 43, 881–899, https://doi.org/10.5194/angeo-43-881-2025, 2025
During geomagnetic storms, Joule heating is a major heating source of the upper atmosphere that is not well estimated, due to a lack of measurements. This leads to uncertainties in orbital calculations. We present simulations with commonly used physics-based models and empirical models that provide measurements of Joule heating. The results show great discrepancies, pointing to the need for measurements in the Earth's Lower Thermosphere-Ionosphere at altitudes where Joule heating maximizes.

Establishing a European Heliophysics Community (EHC)

Mon, 15 Dec 2025 18:06:29 +0100

Establishing a European Heliophysics Community (EHC)
Rumi Nakamura, Thierry Dudok de Wit, Geraint H. Jones, Matt G. G. T. Taylor, Nicolas André, Charlotte Goetz, Lina Z. Hadid, Laura A. Hayes, Heli Hietala, Caitríona M. Jackman, Larry Kepko, Aurélie Marchaudon, Adam Masters, Mathew Owens, Noora Partamies, Stefaan Poedts, Jonathan Rae, Yuri Shprits, Manuela Temmer, Daniel Verscharen, and Robert F. Wimmer-Schweingruber
Ann. Geophys., 43, 855–879, https://doi.org/10.5194/angeo-43-855-2025, 2025
Heliophysics spans a wide range of disciplines covering the study of the Sun and the different Solar System bodies, such as Earth and other planets, moons, comets, and asteroids, and their interactions with the Sun, focusing on plasma and atmospheric processes. A grass-roots effort has been recently started toward establishing a European Heliophysics Community (https://www.heliophysics.eu/). This white paper outlines the motivation, priorities, and a future vision of Heliophysics in Europe.