https://angeo.copernicus.org/articles/ Combined list of the recent articles of the journal Annales Geophysicae and the recent discussion forum Annales Geophysicae Discussions en https://doi.org/10.5194/angeo-44-1093-2026 Ultraviolet observations of the Earth and Moon during the JUICE Lunar-Earth flyby Philippa M. Molyneux, Michael W. Davis, Rohini S. Giles, Thomas K. Greathouse, Kurt D. Retherford, Maarten H. Versteeg, Sue A. Ferrell, Tracy M. Becker, G. Randall Gladstone, Bradley J. Trantham, Joshua A. Kammer, Matthew A. Freeman, and Steven C. Persyn Ann. Geophys., 44, 1093–1108, https://doi.org/10.5194/angeo-44-1093-2026, 2026 We describe observations of the Earth and moon performed by the ultraviolet spectrograph (UVS) on the European Space Agency’s JUICE mission during a lunar-Earth flyby in 2024. JUICE-UVS observed UV sunlight reflected by the moon’s surface, and atmospheric emissions at the Earth. The observations provide the first opportunity to test the UVS response to planetary targets and demonstrate the types of measurements to be performed in the 2030s, when JUICE will explore Jupiter and its icy moons. Thu, 15 Oct 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-1075-2026 In-flight receiver calibration of the Ganymede Laser Altimeter (GALA) by passive Earth observations Gaku Nishiyama, Alexander Stark, Klaus-Dieter Matz, Christian Hüttig, Kai Wickhusen, Livio Agostini, Christian Althaus, Jan Binger, Keigo Enya, Janot George, Kay Lingenauber, Jun Kimura, Masanori Kobayashi, Giulio Macrì, Wladimir Neumann, Luca Penasa, Ganna Portyankina, Cecilia Tubiana, Konrad Willner, Pasquale Palumbo, and Hauke Hussmann Ann. Geophys., 44, 1075–1092, https://doi.org/10.5194/angeo-44-1075-2026, 2026 In-flight calibration of the Ganymede Laser Altimeter (GALA) aboard Juice mission is important for measuring topography and tidal deformation of icy moons as well as surface reflectance. Using passive Earth observations, this study establishes a framework for receiver calibration in comparison with images. As a result, we report that GALA may have experienced a post-launch boresight offset over 700 μrad, together with the radiometric calibration for future reflectance measurements by GALA. Wed, 14 Oct 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-1043-2026 JUICE-JANUS observations of Earth in preparation for the JANUS investigation of Jupiter's atmosphere Ricardo Hueso, Arrate Antuñano, Luisa María Lara, Katrin Stephan, Angelo Zinzi, Athena Coustenis, Yoav Yair, Mitsuteru Sato, Junichi Haruyama, Amy Simon, Cecilia Tubiana, Luca Penasa, Livio Agostini, Alice Lucchetti, Alessio Aboudan, Michael Aye, Elke Kersten, Klaus-Dieter Matz, Romolo Politi, Frank Trauthan, Ry Evill, Ines Belgacem, Takahashi Yukihiro, Jose María Castro-Marin, Vincenzo Della Corte, Stubbe Hviid, Thomas Roatsch, Nicole Schmitz, Manish Patel, Ganna Portyankina, and Pasquale Palumbo Ann. Geophys., 44, 1043–1073, https://doi.org/10.5194/angeo-44-1043-2026, 2026 JANUS (Jovis, Amorum ac Natorum Undique Scrutator), the high-resolution camera on ESA’s JUICE (JUpiter ICy moons Explorer) mission, observed Earth during the August 2024 Lunar–Earth Gravity Assist. Images from a close flyby captured night- and day-side atmospheric phenomena, and a distant view resulted in a low-resolution Earth portrait. These observations validate JANUS performance and demonstrate the instrument’s capabilities. We focus our analysis on characterizing atmospheric systems that provide relevant examples for future studies of Jupiter’s atmosphere. Tue, 13 Oct 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-1023-2026 Statistical properties of internal modulation in pulsating aurora Sota Nanjo, Tomoe Taki, Keisuke Hosokawa, Urban Brändström, Yoshizumi Miyoshi, and Magnar G. Johnsen Ann. Geophys., 44, 1023–1042, https://doi.org/10.5194/angeo-44-1023-2026, 2026 Pulsating aurora often contains rapid brightness changes, but their overall behavior has not been well measured. We analyzed high-speed camera images from northern Sweden and Norway with machine learning to identify when these rapid changes occur. We found that they become more common toward the morning and at the lower-latitude sector. This suggests that small-scale auroral fluctuation can help reveal how particles from near-Earth space enter the upper atmosphere. Mon, 12 Oct 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-1003-2026 High-latitude auroral and cloudiness occurrence from automatic image classification Noora Partamies and Mikko Syrjäsuo Ann. Geophys., 44, 1003–1022, https://doi.org/10.5194/angeo-44-1003-2026, 2026 We developed a method to prune colour all-sky images into classes of clear or cloudy skies with and without aurora using supervised learning and pre-trained convolutional neural network. We investigate a 10-year database of auroral images taken from Svalbard. The method accuracy is well over 90 %, and the results show that about 2/3 of auroral images are cloudy with the cloudiest month being November. Aurora are most often observed in the morning hours independent on the solar activity. Thu, 01 Oct 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-977-2026 Ionospheric currents and auroral signatures during successive earthward bursty bulk flows and dipolarization: a 7 December 2023 case study Vanina Lanabere, Stephan Buchert, Adrian Blagau, Harriet George, Sota Nanjo, Liisa Juusola, Andrew P. Dimmock, Samuel Wharton, Heikki Vanhamäki, Octav Marghitu, Louis Richard, Lei Cai, Alice V. L. Wallner, Daria Kotova, Yaqi Jin, Theresa Hoppe, Jennifer A. Carter, and Anita Aikio Ann. Geophys., 44, 977–1001, https://doi.org/10.5194/angeo-44-977-2026, 2026 We studied a series of fast plasma streams that connected Earth’s nightside magnetic environment with the high‑latitude ionized upper atmosphere on 7 December 2023. Using satellite, auroral images and ground observations, we showed how each stream disturbed the upper atmosphere. Their repeated impact strengthened these disturbances until a substorm began, revealing how small events can build up to a larger magnetic disruption. Wed, 30 Sep 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-959-2026 Mesoscale structure of flickering aurora from wide-field high-speed imaging Sota Nanjo, Satoshi Kurita, Tima Sergienko, Yoshizumi Miyoshi, and Ryuho Kataoka Ann. Geophys., 44, 959–975, https://doi.org/10.5194/angeo-44-959-2026, 2026 Using a high-speed camera with a wide view of the sky, we observed rapidly blinking aurora across several hundred kilometers. We found that different parts of the same auroral arc can blink at different rhythms at the same time, and that these rhythms move together with the arc. Although larger bright patches sometimes blink more slowly, this pattern does not hold overall. These results improve our understanding of how invisible space processes shape the visible northern lights. Fri, 25 Sep 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-949-2026 Deducing spatial characteristics of global thunderstorm activity using the observed Schumann resonance frequencies Oleksandr Koloskov, Masashi Hayakawa, and Alexander P. Nickolaenko Ann. Geophys., 44, 949–957, https://doi.org/10.5194/angeo-44-949-2026, 2026 To study global thunderstorm activity we analysed the Schumann Resonance electromagnetic field driven by lightning. We developed formulas to calculate both the distance and the size of thunderstorm areas from frequency changes of either the magnetic or the electric resonance modes alone. Our method can be used by observatories worldwide, which mainly record magnetic fields. This novel technique improves our ability to monitor and understand global lightning activity. Fri, 18 Sep 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-937-2026 Flying through the plasmasphere to optimize low-energy ion measurements Gabriella Stenberg Wieser, Martin Wieser, Stas Barabash, Philipp Wittmann, Leif Kalla, Markus Fränz, Elias Roussos, Audrey Vorburger, Peter Wurz, Jan-Erik Wahlund, Pontus C. Brandt, Yoshifumi Futaana, Manabu Shimoyama, Angèle Pontoni, André Galli, Andreas Riedo, George Ho, Donald G. Mitchell, George Clark, Peter Kollmann, Malamati Gkioulidou, Leonardo Regoli, Norbert Krupp, Robert Wimmer-Schweingruber, Kazushi Asamura, Esa Kallio, Andrea Opitz, Manuel Grande, Andrew Coates, Geraint Jones, Theodoros Sarris, Andrey Fedorov, Nicolas André, and Ján Baláž Ann. Geophys., 44, 937–948, https://doi.org/10.5194/angeo-44-937-2026, 2026 We used Juice flyby of Earth in August 2024 to evaluate the performance of the Jovian Plasma Dynamics and Composition analyzer (JDC). JDC measures positive and negative ions as well as electrons. When Juice arrives at Jupiter, one of the most challenging tasks for JDC is to record low energy ion populations. We used the data JDC recorded close to Earth, together with measurement in the laboratory on ground, to improve the future observations the sensor will make around Jupiter’s icy moons. Thu, 17 Sep 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-921-2026 Non-Maxwellian electron distributions in the D region during artificial heating – Part 1: Model development and electron temperature Margaretha Myrvang and Björn Gustavsson Ann. Geophys., 44, 921–935, https://doi.org/10.5194/angeo-44-921-2026, 2026 This paper investigate how radio wave heating affect the electron distribution in the D region. Radio wave heating can lead to absorption of radio wave energy by electrons, thereby increasing the temperature. Electrons are cooled by inelastic collisions with the neutrals atmosphere, affecting the electron distribution since electrons lose energy by exciting different states in neutrals. Thus, electrons are redistributed to lower energies, which changes the shape of the electron distribution. Tue, 15 Sep 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-903-2026 Estimating the source altitude of auroral precipitation from dispersed Alfvén waves in the dayside ionosphere Etienne Gavazzi, Andres Spicher, Björn Gustavsson, Juha Vierinen, James Clemmons, Robert Pfaff, and Douglas Rowland Ann. Geophys., 44, 903–920, https://doi.org/10.5194/angeo-44-903-2026, 2026 Auroras are caused by energetic electrons entering the upper atmosphere. For the smallest and most dynamic auroras, scientists think electrons are accelerated by waves (called Alfvén waves) thousands of kilometers above Earth. In this paper, we analyse data from a rocket that flew through auroras, applying existing and new techniques to estimate where the acceleration took place. Our results match theory, and we show how they can be used to study conditions in the near-Earth space environment. Fri, 04 Sep 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-881-2026 Magnetotail response to corotating interaction region driven geomagnetic storms: Cluster observations Adriane Marques de Souza Franco, Rashmi Rawat, Mauricio José Alves Bolzan, and Ezequiel Echer Ann. Geophys., 44, 881–901, https://doi.org/10.5194/angeo-44-881-2026, 2026 This study investigates 40 geomagnetic storms driven by corotating interaction regions and their impact on Earth's magnetotail. We find that short, 4 h energy pulses dominate the magnetotail during cyclic substorms. Furthermore, High-Intensity, Long-Duration, Continuous Auroral Activity (HILDCAA) events in the recovery phase facilitate energy distribution across 2–12 h periodicities in the auroral region. Spectral indices indicate strong turbulence in both regions. Tue, 01 Sep 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-855-2026 Dune aurora: survey from a citizen science database Maxime Grandin, Liisa Juusola, Noora Partamies, Emma Bruus, Joona Rautiainen, Donna Lach, Jia Jia, Max van de Kamp, Eero Karvinen, Kirsti Kauristie, and Theresa Hoppe Ann. Geophys., 44, 855–880, https://doi.org/10.5194/angeo-44-855-2026, 2026 Dune aurora is an intriguing phenomenon recently discovered thanks to citizen science. It is a dim, diffuse auroral form exhibiting wave-like stripes of brighter emission. We carry out the first statistical study of dune aurora, using 308 observation reports submitted to the Skywarden database by citizen scientists from Europe, North America, and Oceania. We find that dunes are an evening phenomenon, most often reported in March and October and associated with currents in the auroral atmosphere. Thu, 27 Aug 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-825-2026 Post launch spectral and radiometric performances of MAJIS, the VIS-NIR imaging spectrometer of JUICE Yves Langevin, Sébastien Rodriguez, Sandrine Guerlet, François Poulet, Giuseppe Piccioni, Livio Agostini, Raymond Armante, Emiliano D'Aversa, Gianrico Filacchione, Leigh Fletcher, Fabrizio Oliva, Clément Royer, Benoît Seignovert, Katrin Stephan, Federico Tosi, and Tim Trent Ann. Geophys., 44, 825–853, https://doi.org/10.5194/angeo-44-825-2026, 2026 We present an updated spectral and radiometric calibration of the Moons and Jupiter Imaging Spectrometer (MAJIS) aboard the Jupiter Icy Moons Explorer (JUICE), based on results of Earth and Moon observations in August 2024 and on observations of the MAJIS internal calibration unit. Very good agreements were obtained with results of other instruments and models. These MAJIS observations provide a promising teaser of what will be achieved by MAJIS in the system of Jupiter. Wed, 26 Aug 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-811-2026 High latitude, dayside rapid geomagnetic variations observed with ground-based magnetometers in Greenland Marie Vigger Eldor, Magnar Gullikstad Johnsen, Nils Olsen, and Anna Naemi Willer Ann. Geophys., 44, 811–823, https://doi.org/10.5194/angeo-44-811-2026, 2026 Rapid geomagnetic variations in the ultra-low frequency band are observed using ground-based magnetometers. We apply four years of data from West Greenland in a statistical analysis of the distribution of such variations. We identify a rapid geomagnetic variation population associated with the magnetospheric cusp that is separate from the auroral oval during summer. Earlier studies, which were mainly performed in winter, failed to unambiguously identify these variations. Mon, 24 Aug 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-795-2026 Juice/SWI during the Lunar-Earth-Gravity-Assist (LEGA) – Part 3: Observations of the Earth as calibration target Christopher Jarchow, Ladislav Rezac, Paul Hartogh, Ali Schulz-Ravanbakhsh, Thibault Cavalié, Fabrice Herpin, Raphael Moreno, and Axel Murk Ann. Geophys., 44, 795–809, https://doi.org/10.5194/angeo-44-795-2026, 2026 The Jupiter Icy Moons Explorer is a spacecraft sent towards Jupiter to perform detailed observations of the giant gas planet & its Galilean satellites. The Submillimetre Wave Instrument onboard this spacecraft is a newly built instrument, which first of all has to demonstrate proper performance before the observed data can be trusted. Using the Earth as a well-known observation target, proper functionality of this instrument has been verified during the Lunar Earth Gravity Assist in August 2024. Fri, 21 Aug 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-773-2026 Storm-time energy budget in the high latitude lower thermosphere–ionosphere: quantification of energy exchange and comparison of different drivers in TIE-GCM Stelios Tourgaidis, Theodoros Sarris, Dimitrios Baloukidis, Stephan Buchert, Panagiotis Pirnaris, Konstantinos Papadakis, and Athanasios Balafoutis Ann. Geophys., 44, 773–793, https://doi.org/10.5194/angeo-44-773-2026, 2026 The Lower Thermosphere-Ionosphere energy balance is driven by complex interactions between ions, neutrals and electrons. These processes are understood theoretically, but their estimates show large discrepancies between models. We calculate the storm-time energy budget according to the neutrals, ions and electrons using TIE-GCM (Thermosphere Ionosphere Electrodynamics General Circulation Model) using two different external drivers. Discrepancies between the model runs are discussed and the way forward to close the gaps in present knowledge is highlighted. Wed, 19 Aug 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-765-2026 A near-sunset atmospheric sounding during the 14 October 2023 annular solar eclipse over Natal Igo Paulino, Francisco Raimundo da Silva, Ana Roberta Paulino, and Gilvan Borba Ann. Geophys., 44, 765–772, https://doi.org/10.5194/angeo-44-765-2026, 2026 The study utilized a stratospheric balloon over Natal, Brazil, to investigate the atmospheric response to the 14 October 2023 annular solar eclipse near sunset. Measurements included temperature, pressure, relative humidity and ozone. Significant changes in these parameters were found at different altitudes. These complex changes confirm the importance of the annular eclipses as a driver of localized atmospheric dynamics. Tue, 18 Aug 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-743-2026 Magnetosphere–ionosphere response to the 21 and 25 June 2015 coronal mass ejections Somaiyeh Sabri and Stefaan Poedts Ann. Geophys., 44, 743–763, https://doi.org/10.5194/angeo-44-743-2026, 2026 Coronal mass ejections (CMEs) threaten Earth. We studied their interaction with the magnetosphere and ionosphere. Using the European Heliospheric Forecasting Information Asset (EUHFORIA), we calculated CME arrival times and investigated Earth's responses. Results show EUHFORIA and Gorgon-Space codes agree well in simulating CME propagation and interactions. Mon, 17 Aug 2026 21:07:53 +0200 https://doi.org/10.5194/angeo-44-731-2026 Analysis of 3GM High Accuracy Accelerometer data collected during JUICE lunar earth gravity assist Umberto De Filippis, Paolo Cappuccio, Mauro Di Benedetto, Ivan di Stefano, Daniele Durante, and Luciano Iess Ann. Geophys., 44, 731–741, https://doi.org/10.5194/angeo-44-731-2026, 2026 The High Accuracy Accelerometer calibrated data collected during the JUICE (JUpiter ICy moons Explorer) Lunar Earth Gravity assist flyby was compared with predicted non-gravitational signals derived from analytical models, showing good agreement. Moon gravity gradient and thermoelastic displacement of solar array during the penumbra phases have been detected. High Accurate Accelerometer detected also unexpected signals such as instrument interference and outgassing event. Fri, 14 Aug 2026 21:07:53 +0200