Последние статьи в Annales Geophysicae

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Combined list of the recent articles of the journal Annales Geophysicae and the recent discussion forum Annales Geophysicae Discussions
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Development of a formalism for computing in situ transits of Earth-directed CMEs – Part 2: Towards a forecasting tool

Fri, 06/05/2020 - 13:30
Development of a formalism for computing in situ transits of Earth-directed CMEs – Part 2: Towards a forecasting tool
Pedro Corona-Romero and Pete Riley
Ann. Geophys., 38, 657–681, https://doi.org/10.5194/angeo-38-657-2020, 2020
Solar storms are natural phenomena that affect technologies on which our societies are highly dependent. The understanding of solar storms and the capability to anticipate their effects on our technologies is of main interest to shield our societies. In this work we present a semi-empirical approach to increase our understanding of solar storms when they hit our planet. Additionally, we also preset a possible pathway to forecast the transits of solar storms by our planet's orbit.
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Odd hydrogen response thresholds for indication of solar proton and electron impact in the mesosphere and stratosphere

Tue, 06/02/2020 - 13:30
Odd hydrogen response thresholds for indication of solar proton and electron impact in the mesosphere and stratosphere
Tuomas Häkkilä, Pekka T. Verronen, Luis Millán, Monika E. Szela̧g, Niilo Kalakoski, and Antti Kero
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-36,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
The atmospheric impacts of energetic particle precipitation (EPP) can be useful in understanding the uncertainties of measuring the precipitation. Hence information on how strong of an EPP flux has observable atmospheric impacts is needed. In this study we find such threshold flux values using odd hydrogen concentrations from both satellite observations and model simulations. We consider effects of solar proton events and radiation belt electron precipitation in the middle atmosphere.
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Vlasov simulation of electrons in the context of hybrid global models: A Vlasiator approach

Tue, 06/02/2020 - 13:30
Vlasov simulation of electrons in the context of hybrid global models: A Vlasiator approach
Markus Battarbee, Thiago Brito, Markku Alho, Yann Pfau-Kempf, Maxime Grandin, Urs Ganse, Konstantinos Papadakis, Andreas Johlander, Lucile Turc, Maxime Dubart, and Minna Palmroth
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-31,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
We investigate local acceleration dynamics of electrons with a new numerical simulation method, which is an extension of a world-leading kinetic plasma simulation. We describe how large supercomputer simulations can be used to initialize the electron simulations, and show numerical stability for the electron method. We briefly show that features of our simulated electrons match observations from Earth's magnetic tail region.
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Non-locality of Earth's quasi-parallel bow shock: injection of thermal protons in a hybrid-Vlasov simulation

Tue, 05/26/2020 - 13:30
Non-locality of Earth's quasi-parallel bow shock: injection of thermal protons in a hybrid-Vlasov simulation
Markus Battarbee, Urs Ganse, Yann Pfau-Kempf, Lucile Turc, Thiago Brito, Maxime Grandin, Tuomas Koskela, and Minna Palmroth
Ann. Geophys., 38, 625–643, https://doi.org/10.5194/angeo-38-625-2020, 2020
The structure and medium-scale dynamics of Earth's bow shock and how charged solar wind particles are reflected by it are studied in order to better understand space weather effects. We use advanced supercomputer simulations to model the shock and reflected ions. We find that the thickness of the shock depends on solar wind conditions but also has small-scale variations. Charged particle reflection is shown to be non-localized. Magnetic fields are important for ion reflection.
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Variability of the lunar semidiurnal tidal amplitudes in the ionosphere over Brazil

Tue, 05/26/2020 - 13:30
Variability of the lunar semidiurnal tidal amplitudes in the ionosphere over Brazil
Ana Roberta Paulino, Fabiano da Silva Araújo, Igo Paulino, Cristiano Max Wrasse, Lourivaldo Mota Lima, Paulo Prado Batista, and Inez Staciarini Batista
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-34,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
Long and short period oscillations in the lunar semidiurnal tidal amplitudes in the ionosphere derived from the total electron content were investigated over Brazil from 2011 to 2014. The results showed  annual, semiannual and intra-seasonal as the dominant components. Additionally, The most pronounced short period oscillation was the 7–11 days which presented characteristics compatible with the quasi 10 days planetary wave, suggesting a possible coupling process from the lower atmosphere.
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Helium in the Earth’s foreshock: a global Vlasiator survey

Mon, 05/25/2020 - 13:30
Helium in the Earth’s foreshock: a global Vlasiator survey
Markus Battarbee, Xochitl Blanco-Cano, Lucile Turc, Primož Kajdič, Andreas Johlander, Vertti Tarvus, Stehphen Fuselier, Karlheinz Trattner, Markku Alho, Thiago Brito, Urs Ganse, Yann Pfau-Kempf, Mojtaba Akhavan-Tafti, Tomas Karlsson, Savvas Raptis, Maxime Dubart, Maxime Grandin, Jonas Suni, and Minna Palmroth
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-29,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
We investigate the dynamics of helium in the foreshock, a part of near-Earth space found upstream of the Earth's bow shock. We show how the second-most common ion in interplanetary space reacts strongly to plasma waves found in the foreshock. Spacecraft observations and supercomputer simulations together give us new understanding of the foreshock edge and how to interpret future observations.
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Variability of Relativistic Electron Flux (E > 2 MeV) during Geo-Magnetically Quiet and Disturbed days: A Case Study

Mon, 05/25/2020 - 13:30
Variability of Relativistic Electron Flux (E > 2 MeV) during Geo-Magnetically Quiet and Disturbed days: A Case Study
Tulsi Thapa, Binod Adhikari, Prashrit Baruwal, and Kiran Pudasainee
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-35,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
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Wavevector spectral signature of decay instability in space plasmas

Mon, 05/18/2020 - 13:30
Wavevector spectral signature of decay instability in space plasmas
Horia Comisel, Yasuhito Narita, and Uwe Motschmann
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-25,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
Identification of a large-amplitude Alfven wave decaying into a pair of ion-acoustic and daughter Alfven waves is one of the major goals in the observational studies of space plasma nonlinearity. In this study, the decay instability is analytically evaluated in the 2-D wavenumber domain spanning the parallel and perpendicular directions to the mean magnetic field. The growth-rate determination of the density perturbations is based on the Hall-MHD wave-wave coupling theory for circularly-polarized Alfven waves. The diagrams of the growth rates versus the wavenumber and propagation angle derived in analytical studies are replaced by 2-D wavenumber distributions and compared with the corresponding wavevector spectrum of density and magnetic field fluctuations. The actual study reveals a perpendicular-shape spectral pattern consistent with the result of a previous study based on 3-D hybrid numerical simulations. The wavevector signature of the decay instability observed in the two-dimensional wavenumber domain ceases at values of plasma beta larger than beta = 0.1. Growth-rate maps serve as a useful tool for predictions of the wavevector spectrum of density or magnetic field fluctuations in various scenarios for the wave-wave coupling processes developing at different stages in space plasma turbulence.
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Ionospheric Anomalies Associated with Mw7.3 Iran-Iraq Border Earthquake and a Moderate Magnetic Storm

Mon, 05/18/2020 - 13:30
Ionospheric Anomalies Associated with Mw7.3 Iran-Iraq Border Earthquake and a Moderate Magnetic Storm
Erman Şentürk, Samed İnyurt, and İbrahim Sertçelik
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-27,2020
Preprint under review for ANGEO (discussion: open, 1 comment)
The analysis of the unexpected ionospheric phases before large earthquakes is a popular approach in earthquake prediction studies. In this study, the Total Electron Content (TEC) data of five International GNSS Service (IGS) stations and the Global Ionosphere Maps (GIMs) were used. The Short-time Fourier Transform (STFT) and a running median process were applied on the TEC time series to detect abnormalities before the Mw7.3 Iran-Iraq border earthquake on November 12, 2017. The analyzes showed positive anomalies 8–9 days before the earthquake and some positive/negative anomalies 1–6 days before the earthquake. These anomalies were cross-checked by space weather indices Kp, Dst, F10.7, Bz component of the interplanetary magnetic field (IMF Bz), electric field (Ey), and plasma speed (VSW). The results showed that the anomalies 1–6 days before the earthquake caused by a moderate magnetic storm. Also, the positive anomalies 8–9 days before the earthquake should be related to the Iran-Iraq border earthquake due to quiet space weather, local dispersion, and proximity to the epicenter.
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Tomographic Imaging of a Large Scale TID during the Halloween Storm of 2003

Thu, 05/14/2020 - 13:30
Tomographic Imaging of a Large Scale TID during the Halloween Storm of 2003
Karl Bolmgren, Cathryn Mitchell, Talini Pinto Jayawardena, Gary Bust, and Jon Bruno
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-26,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
Travelling ionospheric disturbances behave like waves in the ionosphere, the ionised upper part of the atmosphere. In this study, we use an ionospheric tomography technique to map the electron content as affected by the passage of a large scale travelling ionospheric disturbance launched during the largest geomagnetic storm observed by modern instruments. This is the first such imaging using this software and to the authors' knowledge the first study of this travelling ionospheric disturbance.
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Occurrence climatology of equatorial plasma bubbles derived using FormoSat-3 ∕ COSMIC GPS radio occultation data

Wed, 05/13/2020 - 13:30
Occurrence climatology of equatorial plasma bubbles derived using FormoSat-3 ∕ COSMIC GPS radio occultation data
Ankur Kepkar, Christina Arras, Jens Wickert, Harald Schuh, Mahdi Alizadeh, and Lung-Chih Tsai
Ann. Geophys., 38, 611–623, https://doi.org/10.5194/angeo-38-611-2020, 2020
The paper focuses on the analyses of the global occurrence of equatorial plasma bubble events using S4 data that were calculated from GPS radio occultation measurements of the FormoSat-3/COSMIC mission. The advantage in using radio occultation data is that we get information not only on the occurrence and intensity of the equatorial bubble events, but also on the altitude distribution. We analyzed a 10.5-year time series of COSMIC data and demonstrated a strong dependence on the solar cycle.
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Even moderate geomagnetic pulsations can cause fluctuations of foF2 frequency of the auroral ionosphere

Wed, 05/13/2020 - 13:30
Even moderate geomagnetic pulsations can cause fluctuations of foF2 frequency of the auroral ionosphere
Nadezda Yagova, Alexander Kozlovsky, Evgeny Fedorov, and Olga Kozyreva
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-16,2020
Preprint under review for ANGEO (discussion: open, 1 comment)
We present a study of ultra-low-frequency waves in the ionosphere and on the ground. These waves are very slow (their periods are about several minutes). They are registered on the ground as geomagnetic pulsations. No simple dependence exists between geomagnetic and ionospheric pulsations. Here we study not only selected pulsations with very high amplitudes but also usual pulsations and try to answer the question, which pulsations’ parameters are favorable for modulation of the ionosphere.
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Radar Imaging with EISCAT 3D

Tue, 05/12/2020 - 13:30
Radar Imaging with EISCAT 3D
Johann Stamm, Juha Vierinen, Juan M. Urco, Björn Gustavsson, and Jorge L. Chau
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-28,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
A new incoherent scatter radar called EISCAT 3D is being constructed in Northern Scandinavia. It will have the capability of producing volumetric images of ionospheric plasma parameters using aperture synthesis radar imaging. This study uses the current design of EISCAT 3D to explore the theoretical radar imaging performance and compares numerical techniques that could be used in practice. Of all imaging algorithms surveyed, the singular value decomposition with regularization gave the best results and was also found to be the most computationally efficient. The estimated imaging performance indicates that the radar will be capable of detecting features down to approximately 90x90 m at a height of 100 km, which corresponds to a ~0.05° angular resolution. The temporal resolution is dependent on the signal-to-noise ratio and range resolution. The signal-to-noise ratio calculations indicate that high resolution imaging of auroral precipitation is feasible. For example, with a range resolution of 1500 m, a time resolution of 10 seconds, and an electron density of 2·10
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Resolution dependence of magnetosheath waves in global hybrid-Vlasov simulations

Mon, 05/11/2020 - 13:30
Resolution dependence of magnetosheath waves in global hybrid-Vlasov simulations
Maxime Dubart, Urs Ganse, Adnane Osmane, Andreas Johlander, Markus Battarbee, Maxime Grandin, Yann Pfau-Kempf, Lucile Turc, and Minna Palmroth
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-24,2020
Preprint under review for ANGEO (discussion: open, 4 comments)
Plasma waves are ubiquitous in the Earth's magnetosphere. They are responsible for many energetic processes happening in Earth's atmosphere, such as auroras. In order to understand these processes, thorough investigations of these waves are needed. We use a state-of-the-art numerical model to do so. Here we investigate the impact of different spatial resolutions in the model on these waves in order to improve in the future the model without wasting computational resources.
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A Comparison of Contact Charging and Impact Ionization in Low Velocity Impacts: Implications for Dust Detection in Space

Mon, 05/11/2020 - 13:30
A Comparison of Contact Charging and Impact Ionization in Low Velocity Impacts: Implications for Dust Detection in Space
Tarjei Antonsen, Ingrid Mann, Jakub Vaverka, Libor Nouzak, and Åshild Fredriksen
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-23,2020
Preprint under review for ANGEO (discussion: open, 0 comments)
This paper discusses the charge generation for impacts of nano- to micro-scale dust on metal surfaces at speeds below a few km/s. By introducing a model of capacitive coupling between the dust and the impact surface, we find that at such low speeds, the charge can be dominated by contact charging as opposed to plasma generation.
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Dust sputtering within the inner heliosphere

Fri, 05/08/2020 - 13:30
Dust sputtering within the inner heliosphere
Carsten Baumann, Margaretha Myrvang, and Ingrid Mann
Ann. Geophys. Discuss., https//doi.org/10.5194/angeo-2020-30,2020
Preprint under review for ANGEO (discussion: open, 2 comments)
Dust grains exist throughout our solar system. This dust is subject to destruction processes like sublimation and sputtering. Sputtering is the erosion of dust through the impact solar wind and can be very effective near the Sun. We performed calculations to find out how import the sputtering process is compared to the sublimation of dust. Recently started spacecraft will probe the proximity of the Sun and measure the dust population. Our work will help to understand these measurements.
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A quasi-experimental coastal region eddy diffusivity applied in the APUGRID model

Mon, 05/04/2020 - 13:30
A quasi-experimental coastal region eddy diffusivity applied in the APUGRID model
Silvana Maldaner, Michel Stefanello, Luis Gustavo N. Martins, Gervásio Annes Degrazia, Umberto Rizza, Débora Regina Roberti, Franciano S. Puhales, and Otávio C. Acevedo
Ann. Geophys., 38, 603–610, https://doi.org/10.5194/angeo-38-603-2020, 2020
In this paper, quasi-empirical convective eddy diffusivity parameterizations for a coastal site are obtained. In the derivation we used Taylor's theory of statistical diffusion and sonic anemometer observations collected at 11 levels on a 140 m high tower in a convective planetary boundary layer. The test of the derived coefficients was solved by solving the equation of diffusion–advection by the fractional step/locally one-dimensional (LOD) methods.
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Localized total electron content enhancements in the Southern Hemisphere

Wed, 04/29/2020 - 13:30
Localized total electron content enhancements in the Southern Hemisphere
Ilya K. Edemskiy
Ann. Geophys., 38, 591–601, https://doi.org/10.5194/angeo-38-591-2020, 2020
This paper investigates a feature in the Southern Hemisphere ionosphere that is observed near midday in the form of a localized enhancement of the electron density. After being discovered in global ionospheric maps, the enhancements were also observed via in situ measurements of the electron concentration. The probability of detecting an enhancement is maximal during the autumn–winter period and does not seem to be directly dependent on geomagnetic indices or solar wind parameters.
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Plasma density gradients at the edge of polar ionospheric holes: the absence of phase scintillation

Fri, 04/24/2020 - 13:30
Plasma density gradients at the edge of polar ionospheric holes: the absence of phase scintillation
Luke A. Jenner, Alan G. Wood, Gareth D. Dorrian, Kjellmar Oksavik, Timothy K. Yeoman, Alexandra R. Fogg, and Anthea J. Coster
Ann. Geophys., 38, 575–590, https://doi.org/10.5194/angeo-38-575-2020, 2020
The boundary of regions with a plasma density much lower than background was investigated in the northern polar cap using observations of ionospheric plasma density. Similar regions with an above-background density have been linked to fluctuations in phase and amplitude in radio waves traversing the density gradient at their boundary. These fluctuations were absent through the gradient in the below-background regions; thus, a minimum of both density and gradient are required for scintillation.
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