Последние статьи в Annales Geophysicae

Short large-amplitude magnetic structures (SLAMS) at Mercury observed by MESSENGER
Tomas Karlsson, Ferdinand Plaschke, Austin N. Glass, and Jim M. Raines
Ann. Geophys., 42, 117–130, https://doi.org/10.5194/angeo-42-117-2024, 2024
The solar wind interacts with the planets in the solar system and creates a supersonic shock in front of them. The upstream region of this shock contains many complicated phenomena. One such phenomenon is small-scale structures of strong magnetic fields (SLAMS). These SLAMS have been observed at Earth and are important in determining the properties of space around the planet. Until now, SLAMS have not been observed at Mercury, but we show for the first time that SLAMS also exist there.

Auroral breakup detection in all-sky images by unsupervised learning
Noora Partamies, Bas Dol, Vincent Teissier, Liisa Juusola, Mikko Syrjäsuo, and Hjalmar Mulders
Ann. Geophys., 42, 103–115, https://doi.org/10.5194/angeo-42-103-2024, 2024
Auroral imaging produces large amounts of image data that can no longer be analyzed by visual inspection. Thus, every step towards automatic analysis tools is crucial. Previously supervised learning methods have been used in auroral physics, with a human expert providing ground truth. However, this ground truth is debatable. We present an unsupervised learning method, which shows promising results in detecting auroral breakups in the all-sky image data.

Impact of solar cycle on the non-linearity of the relationship between the solar wind parameters and geomagnetic conditions
Sanni Hoilijoki, Emilia Kilpua, Adnane Osmane, Lucile Turc, Mikko Savola, Veera Lipsanen, Harriet George, and Milla Kalliokoski
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2024-3,2024
Preprint under review for ANGEO (discussion: open, 0 comments)
Structures originating from the Sun, such as coronal mass ejections and high-speed streams, may impact the Earth's magnetosphere differently. The occurrence rate of these structures depends on the phase solar cycle. We use mutual information to study the change in the statistical dependence between solar wind and inner magnetosphere. We find that the non-linearity between solar wind and inner magnetosphere varies over the solar cycle and during different solar wind drivers.

Deep temporal convolutional networks for F10.7 radiation flux short-term forecasting
Luyao Wang, Hua Zhang, Xiaoxin Zhang, Guangshuai Peng, Zheng Li, and Xiaojun Xu
Ann. Geophys., 42, 91–101, https://doi.org/10.5194/angeo-42-91-2024, 2024
The temporal convolutional network (TCN) approach in deep learning is used to predict the daily value of F10.7. The prediction results for 1–3 d ahead during solar cycle 24 have a high correlation coefficient (R) of 0.98 and a root mean square error (RMSE) of only 5.04–5.18 sfu.

Analysis of diurnal, seasonal and annual variations of fair weather atmospheric potential gradient at reduced number concentration of condensation nuclei from long-term measurements at Świder, Poland
Izabela Pawlak, Anna Odzimek, Daniel Kępski, and Jose Tacza
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2024-1,2024
Preprint under review for ANGEO (discussion: open, 2 comments)
The electric state of the Earth’s atmosphere is manifested in the surface electric potential gradient (PG). In fair weather the PG should follow the variation of the global source of electric current in the atmosphere, called the global electric circuit. The PG is also influenced by local conditions. We use long-term series of PG and analyse PG variations during conditions of low aerosol concentrations to minimise the aerosol influence on PG obscuring its change due to the global source.

Scalar-potential mapping of the steady-state magnetosheath model
Yasuhito Narita, Daniel Schmid, and Simon Toepfer
Ann. Geophys., 42, 79–89, https://doi.org/10.5194/angeo-42-79-2024, 2024
The magnetosheath is a transition layer surrounding the planetary magnetosphere. We develop an algorithm to compute the plasma flow velocity and magnetic field for a more general shape of magnetosheath using the concept of potential field and suitable coordinate transformation. Application to the empirical Earth magnetosheath region is shown in the paper. The developed algorithm is useful when interpreting the spacecraft data or simulation of the planetary magnetosheath region.

Climatological comparison of polar mesosphere summer echoes over the Arctic and Antarctica at 69°
Ralph Latteck and Damian J. Murphy
Ann. Geophys., 42, 55–68, https://doi.org/10.5194/angeo-42-55-2024, 2024
This paper gives an overview of continuous measurements of polar mesophere summer echoes (PMSE) by VHF radars at Andøya (69° N) and Davis (69° S). PMSE signal strengths are of the same order of magnitude; significantly fewer PMSE were observed in the Southern than the Northern Hemisphere. Compared to Andøya, the PMSE season over Davis starts ~7 d later and ends 9 d earlier; PMSE occur less frequently but with greater seasonal/diurnal occurrence variability, reaching higher peak altitudes.

Ionospheric density depletions around crustal fields at Mars and their connection to ion frictional heating
Hadi Madanian, Troy Hesse, Firdevs Duru, Marcin Pilinski, and Rudy Frahm
Ann. Geophys., 42, 69–78, https://doi.org/10.5194/angeo-42-69-2024, 2024
This article investigates certain anomalies in the ionosphere of Mars known as density depletions. It uses in situ measurements of plasma conditions taken by the MAVEN spacecraft around Mars. The statistical analysis of events sheds light on the generation mechanism of these structures.

Characteristic analysis of the differences between total electron content (TEC) values in global ionosphere map (GIM) grids
Qisheng Wang, Jiaru Zhu, and Genxin Yang
Ann. Geophys., 42, 45–53, https://doi.org/10.5194/angeo-42-45-2024, 2024
The GIM data of 2 years from high solar activity (2014) and low solar activity (2021) provided by CODE (Center for Orbit Determination in Europe) are selected to calculate the total electron content (TEC) difference for each grid point in this paper. Based on the calculation of the spatial and temporal variations in the difference values, both spatial and temporal characteristics of the TEC difference values of the four grid points within the grid are analyzed in detail.

Observations of polar mesospheric summer echoes resembling kilometer-scale varicose-mode flows
Jennifer Hartisch, Jorge L. Chau, Ralph Latteck, Toralf Renkwitz, and Marius Zecha
Ann. Geophys., 42, 29–43, https://doi.org/10.5194/angeo-42-29-2024, 2024
Scientists are studying the mesosphere and lower thermosphere using radar in northern Norway. They found peculiar events with strong upward and downward air movements, happening frequently (up to 2.5 % per month) from 2015 to 2021. Over 700 such events were noted, lasting around 20 min and expanding the studied layer. A total of 17 % of these events had extreme vertical speeds, showing their unique nature.

Estimating gradients of physical fields in space
Yufei Zhou and Chao Shen
Ann. Geophys., 42, 17–28, https://doi.org/10.5194/angeo-42-17-2024, 2024
Multiple spacecraft can operate jointly to detect quantities that are unattainable with a single spacecraft. Present constellations typically consist of four spacecraft, and it is established that a planar distribution of the spacecraft should be avoided. This study addresses the configuration problem for future missions of more spacecraft to measure physical gradients of higher orders. As for quadratic gradients, spacecraft must not be on any quadric surface, such as a sphere or cylinder.

High-time-resolution analysis of meridional tides in the upper mesosphere and lower thermosphere at mid-latitudes measured by the Falkland Islands SuperDARN radar
Gareth Chisham, Andrew J. Kavanagh, Neil Cobbett, Paul Breen, and Tim Barnes
Ann. Geophys., 42, 1–15, https://doi.org/10.5194/angeo-42-1-2024, 2024
Solar tides in the atmosphere are driven by solar heating on the dayside of the Earth. They result in large-scale periodic motion of the upper atmosphere. This motion can be measured by ground-based radars. This paper shows that making measurements at a higher time resolution than the standard operation provides a better description of higher-frequency tidal variations. This will improve the inputs to empirical atmospheric models and the benefits of data assimilation.

Investigation of the October effect in VLF signals
Marc Hansen, Daniela Banyś, Mark Clilverd, David Wenzel, and M. Mainul Hoque
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2023-38,2024
Preprint under review for ANGEO (discussion: open, 1 comment)
The VLF amplitude does not show a symmetrical behavior over the year, which would be expected from its dependency on the solar position. The VLF amplitude rather shows a distinctive sharp decrease around October, which is hence called the “October effect”. This study is the first to systematically investigate this October effect, which shows a clear latitudinal dependency.

The Origins of a Near-Ecliptic Merged Interaction Region as a Magnetic-Cloud like Structure Embedded in a Co-rotating Interaction Region
Megan L. Maunder, Claire Foullon, Robert Forsyth, David Barnes, and Jackie Davies
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2023-39,2024
Preprint under review for ANGEO (discussion: final response, 2 comments)
A comparison of observations at different longitudes near the ecliptic demonstrates the progression of the interaction between a Corotating Interaction Region and a Magnetic Cloud Like-structure from West to East. We compare the overall structure with a Coronal Mass Ejection in the mid-latitudes and present a comprehensive discussion of the challenges posed by observing and relating transients not in alignment, across different latitudes and longitudes, and in different solar wind environments.