Последние статьи в Annales Geophysicae

Syndicate content
Combined list of the recent articles of the journal Annales Geophysicae and the recent discussion forum Annales Geophysicae Discussions
Updated: 1 day 2 hours ago

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

Fri, 03/08/2024 - 14:14
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, 0 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.
Categories:

Scalar-potential mapping of the steady-state magnetosheath model

Thu, 03/07/2024 - 14:14
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.
Categories:

Climatological comparison of polar mesosphere summer echoes over the Arctic and Antarctica at 69°

Wed, 02/28/2024 - 14:14
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.
Categories:

Ionospheric density depletions around crustal fields at Mars and their connection to ion frictional heating

Wed, 02/28/2024 - 14:14
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.
Categories:

Characteristic analysis of the differences between total electron content (TEC) values in global ionosphere map (GIM) grids

Tue, 02/20/2024 - 14:14
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.
Categories:

Observations of polar mesospheric summer echoes resembling kilometer-scale varicose-mode flows

Tue, 02/20/2024 - 14:14
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.
Categories:

Estimating gradients of physical fields in space

Tue, 02/06/2024 - 14:14
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.
Categories:

High-time-resolution analysis of meridional tides in the upper mesosphere and lower thermosphere at mid-latitudes measured by the Falkland Islands SuperDARN radar

Fri, 02/02/2024 - 14:14
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.
Categories:

Investigation of the October effect in VLF signals

Thu, 01/11/2024 - 14:14
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.
Categories:

The Origins of a Near-Ecliptic Merged Interaction Region as a Magnetic-Cloud like Structure Embedded in a Co-rotating Interaction Region

Wed, 01/10/2024 - 14:14
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.
Categories:

Ionospheric Upwelling and the Level of Associated Noise at Solar Minimum

Thu, 01/04/2024 - 14:14
Ionospheric Upwelling and the Level of Associated Noise at Solar Minimum
Timothy Wemimo David, Chizurumoke Michael Michael, Darren M. Wright, Adetoro Temitope Talabi, and Abayomi E. Ajetunmobi
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2023-37,2024
Preprint under review for ANGEO (discussion: open, 2 comments)
The Earth’s upper atmospheres are dominated by matter also known as plasma. These plasmas can flow from the lower region, the ionosphere to the further up region of the upper atmosphere, the magnetosphere (and vice-versa), which is described as upwelling. We have analysed data for ionospheric upwelling over the solar minimum period. A main finding is that the noise or rejected data in the dataset was predominant around the local evening and in winter and minimum around local noon and in summer.
Categories:

On mechanisms for high-frequency pump-enhanced optical emissions at 557.7 and 630.0 nm from atomic oxygen in the high-latitude F-region ionosphere

Wed, 12/13/2023 - 14:14
On mechanisms for high-frequency pump-enhanced optical emissions at 557.7 and 630.0 nm from atomic oxygen in the high-latitude F-region ionosphere
Thomas B. Leyser, Tima Sergienko, Urban Brändström, Björn Gustavsson, and Michael T. Rietveld
Ann. Geophys., 41, 589–600, https://doi.org/10.5194/angeo-41-589-2023, 2023
Powerful radio waves transmitted into the ionosphere from the ground were used to study electron energization in the pumped ionospheric plasma turbulence, by detecting optical emissions from atomic oxygen. Our results obtained with the EISCAT (European Incoherent Scatter Scientific Association) facilities in northern Norway and optical detection with the ALIS (Auroral Large Imaging System) in northern Sweden suggest that long-wavelength upper hybrid waves are important in accelerating electrons.
Categories:

Revisiting mirror modes in the plasma environment of comet 67P/Churyumov–Gerasimenko

Tue, 12/12/2023 - 14:14
Revisiting mirror modes in the plasma environment of comet 67P/Churyumov–Gerasimenko
Ariel Tello Fallau, Charlotte Goetz, Cyril Simon Wedlund, Martin Volwerk, and Anja Moeslinger
Ann. Geophys., 41, 569–587, https://doi.org/10.5194/angeo-41-569-2023, 2023
The plasma environment of comet 67P provides a unique laboratory to study plasma phenomena in the solar system. Previous studies have reported the existence of mirror modes at 67P but no further systematic investigation has so far been done. This study aims to learn more about these waves. We investigate the magnetic field measured by Rosetta and find 565 mirror mode signatures. The detected mirror modes are likely generated upstream of the observation and have been modified by the plasma.
Categories:

Local bow shock environment during magnetosheath jet formation: results from a hybrid-Vlasov simulation

Thu, 12/07/2023 - 14:14
Local bow shock environment during magnetosheath jet formation: results from a hybrid-Vlasov simulation
Jonas Suni, Minna Palmroth, Lucile Turc, Markus Battarbee, Giulia Cozzani, Maxime Dubart, Urs Ganse, Harriet George, Evgeny Gordeev, Konstantinos Papadakis, Yann Pfau-Kempf, Vertti Tarvus, Fasil Tesema, and Hongyang Zhou
Ann. Geophys., 41, 551–568, https://doi.org/10.5194/angeo-41-551-2023, 2023
Magnetosheath jets are structures of enhanced plasma density and/or velocity in a region of near-Earth space known as the magnetosheath. When they propagate towards the Earth, these jets can disturb the Earth's magnetic field and cause hazards for satellites. In this study, we use a simulation called Vlasiator to model near-Earth space and investigate jets using case studies and statistical analysis. We find that jets that propagate towards the Earth are different from jets that do not.
Categories:

Theme by Danetsoft and Danang Probo Sayekti inspired by Maksimer