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Seasonal dependence of the Earth's radiation belt – new insights Ann. Geophys. (IF 1.49) Pub Date : 2021-02-24 Rajkumar Hajra
Long-term variations in the relativistic (∼MeV) electrons in the Earth's radiation belt are explored to study seasonal features of the electrons. An L-shell dependence of the seasonal variations in the electrons is reported for the first time. A clear ∼6 month periodicity, representing one/two peaks per year, is identified for 1.5–6.0 MeV electron fluxes in the L shells between ∼3.0 and ∼5.0. The relativistic
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Foreshock cavitons and spontaneous hot flow anomalies: A statistical study with a global hybrid-Vlasov simulation Ann. Geophys. (IF 1.49) Pub Date : 2021-02-24 Vertti Tarvus; Lucile Turc; Markus Battarbee; Jonas Suni; Xóchitl Blanco-Cano; Urs Ganse; Yann Pfau-Kempf; Markku Alho; Maxime Dubart; Maxime Grandin; Andreas Johlander; Konstantinos Papadakis; Minna Palmroth
Abstract. The foreshock located upstream of Earth's bow shock hosts a wide variety of phenomena related to the reflection of solar wind particles from the bow shock and the subsequent formation of ultra-low frequency (ULF) waves. In this work, we investigate foreshock cavitons, which are transient structures resulting from the non-linear evolution of ULF waves, and spontaneous hot flow anomalies (SHFAs)
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Distribution of Earth's radiation belts' protons over the drift frequency of particles Ann. Geophys. (IF 1.49) Pub Date : 2021-02-23 Alexander S. Kovtyukh
Using data on the proton fluxes of the Earth's radiation belts (ERBs) with energy ranging from 0.2 to 100 MeV on the drift L shells ranging from 1 to 8, the quasi-stationary distributions over the drift frequency fd of protons around the Earth are constructed. For this purpose, direct measurements of proton fluxes of the ERBs during the period from 1961 to 2017 near the geomagnetic equator were employed
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Wavevector spectral signature of decay instability in space plasmas Ann. Geophys. (IF 1.49) Pub Date : 2021-02-22 Horia Comişel; Yasuhito Narita; Uwe Motschmann
Identification of a large-amplitude Alfvén wave decaying into a pair of ion-acoustic and daughter Alfvén 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
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Characteristics of Ionospheric Scintillation in Chengdu, China Ann. Geophys. (IF 1.49) Pub Date : 2021-02-19 Song Zhang; Hailong Li; Jinghua Li; Lin Meng
Abstract. When wireless electromagnetic waves pass through the earth's atmosphere, they are affected by ionospheric irregularities, and their amplitude and phase will jitter rapidly in a short period of time, which is called ionospheric scintillation. With the human exploration of outer space and the demand for space communication, the study of ionospheric scintillation characteristics and its influence
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The geomagnetic data of the Clementinum observatory in Prague since 1839 Ann. Geophys. (IF 1.49) Pub Date : 2021-02-19 Pavel Hejda; Fridrich Valach; Miloš Revallo
Abstract. The historical magnetic observatory Clementinum operated in Prague from 1839 to 1926. The data from the yearbooks that recorded the observations at Clementinum have recently been digitized and were subsequently converted in this work into the physical units of the International System of Units (SI). Introducing a database of geomagnetic data from this historical source is a part of our paper
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Variability of the lunar semidiurnal tidal amplitudes in the ionosphere over Brazil Ann. Geophys. (IF 1.49) Pub Date : 2021-02-17 Ana Roberta Paulino; Fabiano da Silva Araújo; Igo Paulino; Cristiano Max Wrasse; Lourivaldo Mota Lima; Paulo Prado Batista; Inez Staciarini Batista
The variability in the amplitudes of the lunar semidiurnal tide was investigated using maps of total electron content over Brazil from January 2011 to December 2014. Long-period variability showed that the annual variation is always present in all investigated magnetic latitudes, and it represents the main component of the temporal variability. Semiannual and triannual (two and three times a year,
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Simulation of Gravity Wave D-region disturbance and its effect on the LWPC simulated VLF signal Ann. Geophys. (IF 1.49) Pub Date : 2021-02-17 Abdellatif Benchafaa; Samir Nait Amor; Ghazali Mebarki
Abstract. In this work we show the result of the numerical simulation of the gravity waves (GWs) D region disturbance. Effectively, using the Glukhov-Pasko-Inan (GPI) model of the electron density in the D region we were figured out the response of the electron density due to gravity wave neutral atmosphere oscillation. As a consequence to the D region disturbance, the electron density sometimes increases
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Io's auroral emissions via global hybrid plasma simulations Ann. Geophys. (IF 1.49) Pub Date : 2021-02-12 Štěpán Štverák; Pavel Trávníček; Ondřej Šebek; David Herčík
Abstract. We tackle the Io's aurora source and topology by carrying out a set of global hybrid simulations of Io's interaction with the plasma torus under different model geometry and background conditions. Based on the simulated results, we compute the photon emission rates above the Io's surface and present the resulting images from a virtual telescope and topological maps showing the distribution
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D-region impact area of energetic electron precipitation during pulsating aurora Ann. Geophys. (IF 1.49) Pub Date : 2021-02-10 Emma Bland; Fasil Tesema; Noora Partamies
A total of 10 radars from the Super Dual Auroral Radar Network (SuperDARN) in Antarctica were used to estimate the spatial area over which energetic electron precipitation (EEP) impacts the D-region ionosphere during pulsating aurora (PsA) events. We use an all-sky camera (ASC) located at Syowa Station to confirm the presence of optical PsAs, and then we use the SuperDARN radars to detect high frequency
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Role of Eddy Diffusion in the Delayed Ionospheric Response to Solar Flux Changes Ann. Geophys. (IF 1.49) Pub Date : 2021-02-09 Rajesh Vaishnav; Christoph Jacobi; Jens Berdermann; Mihail Codrescu; Erik Schmölter
Abstract. Simulations of the ionospheric response to solar flux changes driven by the twenty-seven days solar rotation have been performed using the global 3-D Coupled Thermosphere/Ionosphere Plasmasphere electrodynamics (CTIPe) physics- based numerical model. Using the F10.7 index as a proxy for solar EUV variations in the model, the ionospheric delay at the solar rotation period is well reproduced
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Revisiting the long-term decreasing trend of atmospheric electric potential gradient measured at Nagycenk, Hungary, Central Europe Ann. Geophys. (IF 1.49) Pub Date : 2021-02-09 Attila Buzás; Veronika Barta; Tamás Horváth; József Bór
Abstract. In 2003, a decreasing trend has been reported in the long-term (1962–2001) fair weather atmospheric electric potential gradient (PG) measured in the Széchenyi István Geophysical Observatory (NCK, 47°38' N, 16°43' E), Hungary, Central Europe. The origin of this reduction has been the subject of a long-standing debate, due to a group of trees near the measurement site which reached significant
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Attenuation of Plasmaspheric Hiss Associated with the Enhanced Magnetospheric Electric Field Ann. Geophys. (IF 1.49) Pub Date : 2021-02-05 Haimeng Li; Wen Li; Qianli Ma; Yukitoshi Nishimura; Zhigang Yuan; Alex J. Boyd; Xiaochen Shen; Rongxin Tang; Xiaohua Deng
Abstract. We report an attenuation of hiss wave intensity in the duskside of outer plasmasphere in response to enhanced convection and substorm based on Van Allen Probes observations. Using test particle codes, we simulate the dynamics of energetic electron fluxes based on a realistic magnetospheric electric field model driven by solar wind and subauroral polarization stream. We suggest that the enhanced
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Radar imaging with EISCAT 3D Ann. Geophys. (IF 1.49) Pub Date : 2021-02-04 Johann Stamm; Juha Vierinen; Juan M. Urco; Björn Gustavsson; Jorge L. Chau
A new incoherent scatter radar called EISCAT 3D is being constructed in northern Scandinavia. It will have the capability to produce 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 when imaging electron density in the E region and compares numerical techniques
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Ion distribution functions in magnetotail reconnection: Global hybrid-Vlasov simulation results Ann. Geophys. (IF 1.49) Pub Date : 2021-02-01 Andrei Runov; Maxime Grandin; Minna Palmroth; Markus Battarbee; Urs Ganse; Heli Hietala; Sanni Hoilijoki; Emilia Kilpua; Yann Pfau-Kempf; Sergio Toledo-Redondo; Lucile Turc; Drew Turner
Abstract. We present results of noon–midnight meridional plane global hybrid-Vlasov simulations of the magnetotail ion dynamics under steady southward interplanetary magnetic field using the Vlasiator model. The simulation results show magnetotail reconnection and formation of earthward and tailward fast plasma outflows. The hybrid-Vlasov approach allows us to study ion velocity distribution functions
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Winds and Tides of the Extended Unified Model in the Mesosphere and Lower Thermosphere Validated with Meteor Radar Observations Ann. Geophys. (IF 1.49) Pub Date : 2021-01-29 Matthew J. Griffith; Shaun M. Dempsey; David R. Jackson; Tracy Moffat-Griffin; Nicholas J. Mitchell
Abstract. The Mesosphere and Lower Thermosphere (MLT) is a critical region that must be accurately reproduced in General Circulation Models (GCMs) that aim to include the coupling between the lower & middle atmosphere and the thermosphere. An accurate representation of the MLT is important for improved climate modelling and the development of a whole atmosphere model. This is because the atmospheric
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Auroral ionospheric E region parameters obtained from satellite- based far-ultraviolet and ground-based ionosonde observations – effects of proton precipitation Ann. Geophys. (IF 1.49) Pub Date : 2021-01-28 Harold K. Knight
Coincident auroral far-ultraviolet (FUV) and ground-based ionosonde observations are compared for the purpose of determining whether auroral FUV remote sensing algorithms that assume pure electron precipitation are biased in the presence of proton precipitation. Auroral particle transport and optical emission models, such as the Boltzmann 3-Constituent (B3C) model, predict that maximum E region electron
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Vlasov simulation of electrons in the context of hybrid global models: an eVlasiator approach Ann. Geophys. (IF 1.49) Pub Date : 2021-01-28 Markus Battarbee; Thiago Brito; Markku Alho; Yann Pfau-Kempf; Maxime Grandin; Urs Ganse; Konstantinos Papadakis; Andreas Johlander; Lucile Turc; Maxime Dubart; Minna Palmroth
Modern investigations of dynamical space plasma systems such as magnetically complicated topologies within the Earth's magnetosphere make great use of supercomputer models as well as spacecraft observations. Space plasma simulations can be used to investigate energy transfer, acceleration, and plasma flows on both global and local scales. Simulation of global magnetospheric dynamics requires spatial
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Predictability of the variable solar-terrestrial coupling Ann. Geophys. (IF 1.49) Pub Date : 2021-01-26 Ioannis A. Daglis; Loren C. Chang; Sergio Dasso; Nat Gopalswamy; Olga V. Khabarova; Emilia Kilpua; Ramon Lopez; Daniel Marsh; Katja Matthes; Dibyendu Nandi; Annika Seppälä; Kazuo Shiokawa; Rémi Thiéblemont; Qiugang Zong
Abstract. In October 2017, the Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) Bureau established a committee for the design of SCOSTEP's Next Scientific Program (NSP). The NSP committee members and authors of this paper, decided from the very beginning of their deliberations that the predictability of the Sun-Earth System from a few hours to centuries is a timely scientific topic, combining
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Performance of BDS B1 frequency standard point positioning during the main phase of different classes of geomagnetic storms in China and its surrounding area Ann. Geophys. (IF 1.49) Pub Date : 2021-01-25 Junchen Xue; Sreeja Vadakke Veettil; Marcio Aquino; Xiaogong Hu; Lin Quan; Dun Liu
Abstract. Geomagnetic storms are one of the space weather events. The radio signals transmitted by modern navigation systems suffer from the effects of storms which can degrade the performance of the whole system. In this study, the performance of BeiDou Navigation Satellite System (BDS) B1 frequency standard point positioning in China and its surrounding area during different classes of storms is
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Electron precipitation characteristics during isolated, compound, and multi-night substorm events Ann. Geophys. (IF 1.49) Pub Date : 2021-01-22 Noora Partamies; Fasil Tesema; Emma Bland; Erkka Heino; Hilde Nesse Tyssøy; Erlend Kallelid
A set of 24 isolated, 46 compound, and 36 multi-night substorm events from the years 2008–2013 have been analysed in this study. Isolated substorm events are defined as single expansion–recovery phase pairs, compound substorms consist of multiple phase pairs, and multi-night substorm events refer to recurring substorm activity on consecutive nights. Approximately 200 nights of substorm activity observed
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Influence of different types of ionospheric disturbances on GPS signals at polar latitudes Ann. Geophys. (IF 1.49) Pub Date : 2021-01-21 Vladimir B. Belakhovsky; Yaqi Jin; Wojciech J. Miloch
Abstract. The comparative research of the influence of different types of auroral particle precipitation and polar cap patches (PCP) on the GPS signals disturbances in the polar ionosphere was done. For this purpose, we use the GPS scintillation receivers at Ny-Ålesund and Skibotn, operated by the University of Oslo. The presence of the auroral particle precipitation and polar cap patches was determined
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Ion acoustic waves near a comet nucleus: Rosetta observations at comet 67P/Churyumov–Gerasimenko Ann. Geophys. (IF 1.49) Pub Date : 2021-01-15 Herbert Gunell; Charlotte Goetz; Elias Odelstad; Arnaud Beth; Maria Hamrin; Pierre Henri; Fredrik L. Johansson; Hans Nilsson; Gabriella Stenberg Wieser
Ion acoustic waves were observed between 15 and 30 km from the centre of comet 67P/Churyumov–Gerasimenko by the Rosetta spacecraft during its close flyby on 28 March 2015. There are two electron populations: one cold at kBTe≈0.2 eV and one warm at kBTe≈2 eV. The ions are dominated by a cold (a few hundredths of electronvolt) distribution of water group ions with a bulk speed of (3–3.7) km s−1. A warm
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A Survey on High-energy Protons Response to Geomagnetic Storm in the Inner Radiation Belt Ann. Geophys. (IF 1.49) Pub Date : 2021-01-15 Zhaohai He; Jiyao Xu; Ilan Roth; Chi Wang; Lei Dai
Abstract. RBSPA observations suggest that the inner radiation belt high energy proton fluxes drop significantly during the storm main phase and recover in parallel to as the SYM-H index [Xu et al., 2019]. A natural problem arises: are these storm‐time proton flux variations in response to the magnetic field modifications adiabatic? Based on Liouville's theorem and conservation of the first and third
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Testing the electrodynamic method to derive height-integrated ionospheric conductances Ann. Geophys. (IF 1.49) Pub Date : 2021-01-14 Daniel Weimer; Thom Edwards
We have used empirical models for electric potentials and the magnetic fields both in space and on the ground to obtain maps of the height-integrated Pedersen and Hall ionospheric conductivities at high latitudes. This calculation required use of both “curl-free” and “divergence-free” components of the ionospheric currents, with the former obtained from magnetic fields that are used in a model of the
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Detection of Kelvin-Helmholtz billows over the National Capital Region of India using SODAR Ann. Geophys. (IF 1.49) Pub Date : 2021-01-13 Nishant Kumar; Kirti Soni; Ravinder Agarwal
Abstract. Kelvin-Helmholtz billows (KHB) have been investigated in the Atmospheric Boundary layer (ABL) using Mono-static SODAR (Sound Detection And Ranging) designed and developed by CSIR-National Physical Laboratory, New Delhi over the capital region Delhi of India. KH billows are a primary cause of mixing in stably stratified conditions and hence have been studied widely by researchers by using
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On the semi-annual variation of relativistic electrons in the outer radiation belt Ann. Geophys. (IF 1.49) Pub Date : 2021-01-08 Christos Katsavrias; Constantinos Papadimitriou; Sigiava Aminalragia-Giamini; Ioannis A. Daglis; Ingmar Sandberg; Piers Jiggens
Abstract. The nature of the semi-annual variation in the relativistic electron fluxes in the Earth’s outer radiation belt is investigated using Van Allen Probes (MagEIS and REPT) and GOES (EPS) data during solar cycle 24. We perform wavelet and cross-wavelet analysis in a broad energy and spatial range of electron fluxes and examine their phase relationship with the axial, equinoctial and Russell-McPherron
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Magnetosheath plasma flow model around Mercury Ann. Geophys. (IF 1.49) Pub Date : 2021-01-08 Daniel Schmid; Ferdinand Plaschke; Yasuhito Narita; Martin Volwerk; Rumi Nakamura; Wolfgang Baumjohann
Abstract. The magnetosheath is defined as the plasma region between the bow shock, where the super-magnetosonic solar wind plasma is decelerated and heated, and the outer boundary of the intrinsic planetary magnetic field, the so called magnetopause. Based on the Soucek-Escoubet magnetosheath flow model at Earth, we present the first analytical magnetosheath plasma flow model for Mercury. It can be
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Seasonal evolution of winds, atmospheric tides, and Reynolds stress components in the Southern Hemisphere mesosphere–lower thermosphere in 2019 Ann. Geophys. (IF 1.49) Pub Date : 2021-01-07 Gunter Stober; Diego Janches; Vivien Matthias; Dave Fritts; John Marino; Tracy Moffat-Griffin; Kathrin Baumgarten; Wonseok Lee; Damian Murphy; Yong Ha Kim; Nicholas Mitchell; Scott Palo
In this study we explore the seasonal variability of the mean winds and diurnal and semidiurnal tidal amplitude and phases, as well as the Reynolds stress components during 2019, utilizing meteor radars at six Southern Hemisphere locations ranging from midlatitudes to polar latitudes. These include Tierra del Fuego, King Edward Point on South Georgia island, King Sejong Station, Rothera, Davis, and
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Fine Scale Dynamics of Fragmented Aurora-Like Emission Ann. Geophys. (IF 1.49) Pub Date : 2021-01-07 Daniel K. Whiter; Hanna Dahlgren; Betty S. Lanchester; Joshua Dreyer; Noora Partamies; Nickolay Ivchenko; Marco Zaccaria Di Fraia; Rosie Oliver; Amanda Serpell-Stevens; Tiffany Shaw-Diaz; Thomas Braunersreuther
Abstract. Fragmented Aurora-like Emissions (FAEs) are small (few km) optical structures which have been observed close to the poleward boundary of the aurora from the high-latitude location of Svalbard (magnetic latitude 75.3 ° N). The FAEs are only visible in certain emissions and their shape has no magnetic-field aligned component, suggesting that they are not caused by energetic particle precipitation
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Ionospheric control of space weather Ann. Geophys. (IF 1.49) Pub Date : 2021-01-04 Osuke Saka
Abstract. We propose that ionospheric plasma injections to the magnetosphere (ionospheric injection) represent a new plasma process in the polar ionosphere. The ionospheric injection is first triggered by westward electric fields transmitted from the convection surge in the magnetosphere in association with dipolarization onset. Localized westward electric fields result in local accumulation of ionospheric
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A New Perspective and Explanation to the Formation of Plasmaspheric Shoulder Structure Ann. Geophys. (IF 1.49) Pub Date : 2020-12-28 Hua Zhang; Guangshuai Peng; Chao Shen
Abstract. Over the hours of 5–9 UT on June 8 2001, the extreme ultraviolet (EUV) instrument onboard IMAGE satellite observed a Shoulder-like formation in the morning sector and a Plume-like structure straddling in the between noon and dusk region. Simulation results of the plasmapause formation based on mechanism of drift motion called Test Particle Model (TPM) and have reproduced various plasmapause
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Odd hydrogen response thresholds for indication of solar proton and electron impact in the mesosphere and stratosphere Ann. Geophys. (IF 1.49) Pub Date : 2020-12-22 Tuomas Häkkilä; Pekka T. Verronen; Luis Millán; Monika E. Szeląg; Niilo Kalakoski; Antti Kero
Understanding the atmospheric forcing from energetic particle precipitation (EPP) is important for climate simulations on decadal time scales. However, presently there are large uncertainties in energy flux measurements of electron precipitation. One approach to narrowing these uncertainties is by analyses of EPP direct atmospheric impacts and their relation to measured EPP fluxes. Here we use observations
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Resolution dependence of magnetosheath waves in global hybrid-Vlasov simulations Ann. Geophys. (IF 1.49) Pub Date : 2020-12-21 Maxime Dubart; Urs Ganse; Adnane Osmane; Andreas Johlander; Markus Battarbee; Maxime Grandin; Yann Pfau-Kempf; Lucile Turc; Minna Palmroth
Kinetically driven plasma waves are fundamental for a description of the thermodynamical properties of the Earth's magnetosheath. The most commonly observed ion-scale instabilities are generated by temperature anisotropy of the ions, such as the mirror and proton cyclotron instabilities. We investigate here the spatial resolution dependence of the mirror and proton cyclotron instabilities in a global
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Multipoint observations of compressional Pc5 pulsations in the dayside magnetosphere and corresponding particle signatures Ann. Geophys. (IF 1.49) Pub Date : 2020-12-21 Galina Korotova; David Sibeck; Mark Engebretson; Michael Balikhin; Scott Thaller; Craig Kletzing; Harlan Spence; Robert Redmon
We use Van Allen Probes (Radiation Belt Storm Probes A and B, henceforth RBSP-A and RBSP-B) and GOES-13 and GOES-15 (henceforth G-13 and G-15) multipoint magnetic field, electric field, plasma, and energetic particle observations to study the spatial, temporal, and spectral characteristics of compressional Pc5 pulsations observed during the recovery phase of a strong geomagnetic storm on 1 January 2016
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Migrating tide climatologies measured by a high-latitude array of SuperDARN HF radars Ann. Geophys. (IF 1.49) Pub Date : 2020-12-21 Willem E. van Caspel; Patrick J. Espy; Robert E. Hibbins; John P. McCormack
This study uses hourly meteor wind measurements from a longitudinal array of 10 high-latitude SuperDARN high-frequency (HF) radars to isolate the migrating diurnal, semidiurnal, and terdiurnal tides at mesosphere–lower-thermosphere (MLT) altitudes. The planetary-scale array of radars covers 180∘ of longitude, with 8 out of 10 radars being in near-continuous operation since the year 2000. Time series
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Diurnal mesospheric tidal winds observed simultaneously by meteor radars in Costa Rica (10° N, 86° W) and Brazil (7° S, 37° W) Ann. Geophys. (IF 1.49) Pub Date : 2020-12-17 Ricardo A. Buriti; Wayne Hocking; Paulo P. Batista; Igo Paulino; Ana R. Paulino; Marcial Garbanzo-Salas; Barclay Clemesha; Amauri F. Medeiros
This paper presents a study of diurnal tidal winds observed simultaneously by two meteor radars located on each side of the Equator in the equatorial region. The radars were located in Santa Cruz, Costa Rica (10.3∘ N, 85.6∘ W) (hereafter CR) and São João do Cariri, Brazil (7.4∘ S, 36.5∘ W) (hereafter CA). The distance between the sites is 5800 km. Harmonic analysis has been used to obtain amplitudes
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Dynamics of He++ ions at interplanetary shocks Ann. Geophys. (IF 1.49) Pub Date : 2020-12-16 Olga V. Sapunova; Natalia L. Borodkova; Georgii N. Zastenker; Yuri I. Yermolaev
Abstract. Variations of parameters of twice-ionized helium ions – He++ ions or α-particles – in the solar wind plasma during the interplanetary shock front passage are investigated. We used the data measured by the BMSW (Bright Monitor of Solar Wind) instrument installed on the SPEKTR-R satellite, which operated since August 2011 to 2019 and registered 57 interplanetary shocks. According to received
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Estimating the maximum of the smoothed highest 3-hourly aa index in 3 d by the preceding minimum for the solar cycle Ann. Geophys. (IF 1.49) Pub Date : 2020-12-15 Zhanle Du
Predicting the maximum intensity of geomagnetic activity for an upcoming solar cycle is important in space weather service and for planning future space missions. This study analyzed the highest and lowest 3-hourly aa index (aaH∕aaL) in a 3 d interval, smoothed by 363 d to analyze their variation with the 11-year solar cycle. It is found that the maximum of aaH (aaHmax) is well correlated with the
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Steepening of magnetosonic waves in the inner coma of comet 67P/Churyumov-Gerasimenko Ann. Geophys. (IF 1.49) Pub Date : 2020-12-14 Katharina Ostaszewski; Karl-Heinz Glassmeier; Charlotte Goetz; Philip Heinisch; Pierre Henri; Hendrik Ranocha; Ingo Richter; Martin Rubin; Bruce Tsurutani
Abstract. We present a statistical survey of large amplitude, asymmetric plasma, and magnetic field enhancements at comet 67P/Churyumov-Gerasimenko from December 2014 to June 2016. The aim is to provide a general overview of these structures' properties over the mission duration. At comets, nonlinear wave evolution plays an integral part in the development of turbulence and in particular facilitates
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Ionospheric Response to Solar EUV Radiation Variations: Comparison based on CTIPe Model Simulations and Satellite Measurements Ann. Geophys. (IF 1.49) Pub Date : 2020-12-11 Rajesh Vaishnav; Erik Schmölter; Christoph Jacobi; Jens Berdermann; Mihail Codrescu
Abstract. The ionospheric Total Electron Content (TEC) provided by the International GNSS Service (IGS), and the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) model simulated TEC have been used to investigate the delayed ionospheric response against solar flux and its trend during the years 2011 to 2013. The analysis of the distinct low and mid-latitudes TEC response over 15° E
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Climatology of ionosphere over Nepal based on GPS TEC data from 2008 to 2018 Ann. Geophys. (IF 1.49) Pub Date : 2020-12-11 Drabindra Pandit; Basudev Ghimire; Christine Amory-Mazaudier; Rolland Fleury; Narayan Prasad Chapagain; Binod Adhikari
Abstract. In this study, we analyze the climatology of ionosphere over Nepal based on GPS derived VTEC observed from four stations: KKN4 (27.80° N, 85.27° E), GRHI (27.95° N, 82.49° E), JMSM (28.80° N, 83.74° E), DLPA (28.98° N,82.81° E) during years 2008 to 2018. The study illustrates the diurnal, monthly, annual, seasonal and solar cycle variations of VTEC during all time of solar cycle 24. The results
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Neutral air turbulence in the mesosphere and associated polar mesospheric summer echoes (PMSEs) Ann. Geophys. (IF 1.49) Pub Date : 2020-12-08 Alireza Mahmoudian; Mike J. Kosch; Wayne A. Scales; Michael T. Rietveld; Henry Pinedo
Abstract. This paper presents the first simultaneous four radar frequency observations of the PMSE region under varying neutral air turbulence conditions. Radar frequencies of 8, 56, 224, and 930 MHz are used in this study. Three days of experimental observations associated with EISCAT are presented. Numerical simulations of mesospheric dusty/ice plasma associated with the observed radar frequencies
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Requirement of HE-PIXE at High Z Elements in Charnockite Matrix Composition Ann. Geophys. (IF 1.49) Pub Date : 2020-12-08 Avupati Venkata Surya Satyanarayana; Mokka Jagannadha Rao; Byreddy Seetharami Reddy
Abstract. The maximum of Proton Induced X-ray Emission analytical technique on metamorphic rocks in geology has used 3 MeV range proton beams for excitation of thick targets. Protons of such energies do not accurately excite K-X–rays for high Z elements in matrix geological compositions like charnockite. In this analysis, low-energy PIXE (LE-PIXE) uses K-X-rays of Low Z elements and L-X-ray series
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Microbarom radiation and propagation model assessment using infrasound recordings: a vespagram-based approach Ann. Geophys. (IF 1.49) Pub Date : 2020-12-08 Ekaterina Vorobeva; Marine De Carlo; Alexis Le Pichon; Patrick Joseph Espy; Sven Peter Näsholm
Abstract. This study investigates the use of a vespagram-based approach as a tool for multi-directional comparison between simulated microbarom soundscapes and infrasound data recorded at ground-based array stations. Data recorded at the IS37 station in northern Norway during 2014–2019 have been processed to generate vespagrams (velocity spectral analysis) for five frequency bands between 0.1 and 0
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Semi-Annual Variation of Excited Hydroxyl Emission at Mid-Latitudes Ann. Geophys. (IF 1.49) Pub Date : 2020-12-07 Mykhaylo Grygalashvyly; Alexander I. Pogoreltsev; Alexey B. Andreyev; Sergei P. Smyshlyaev; Gerd R. Sonnemann
Abstract. Ground-based observations show a phase shift in semi-annual variation of excited hydroxyl (OH*) emissions at mid-latitudes (43° N) compared to those at low latitudes. This differs from the annual cycle at high latitudes. We examine this behaviour utilising an OH* airglow model which was incorporated into the 3D chemistry-transport model (CTM). Through this modelling, we study the morphology
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Comment on Invariability of relationship between the polar cap magnetic activity and geoeffective interplanetary electric field by Troshichev et al. (2011) Ann. Geophys. (IF 1.49) Pub Date : 2020-12-04 Peter Stauning
Abstract. In the publication Troshichev et al. (2006) on the Polar Cap (PC) indices, PCN (North) and PCS (South), an error was made by using components of the Interplanetary Magnetic Field (IMF) in their Geocentric Solar Ecliptic (GSE) representation instead of the prescribed Geocentric Solar Magnetosphere (GSM) representation for calculations of index scaling parameters in the version AARI_1998-2001
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Comment on Identification of the IMF sector structure in near-real time by ground magnetic data by Janzhura and Troshichev (2011) Ann. Geophys. (IF 1.49) Pub Date : 2020-12-04 Peter Stauning
Abstract. The only published description of the solar wind sector (SS) term used for the reference level in the post-event and real-time derivation of the Polar Cap (PC) indices, PCN (North) and PCS (South), in the version endorsed by the International Association for Geomagnetism and Aeronomy (IAGA) is found in the commented publication, Janzhura and Troshichev (2011): Identification of the IMF sector
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Thermal electron anisotropy driven by kinetic Alfven waves in the Earth's magnetotail Ann. Geophys. (IF 1.49) Pub Date : 2020-11-27 Alexander Lukin; Anton Artemyev; Evgeny Panov; Rumi Nakamura; Anatoly Petrukovich; Robert Ergun; Barbara Giles; Yuri Khotyaintsev; Per Arne Lindqvist; Christopher Russell; Robert Strangeway
Abstract. Thermal and subthermal electron populations in the Earth's magnetotail are usually characterized by pronounced field-aligned anisotropy that contributes to generation of strong electric currents within the magnetotail current sheet. Formation of this anisotropy requires electron field-aligned acceleration, and thus likely involves field-aligned electric fields. Such fields can be carried
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Modeling total electron content derived from radio occultation measurements by COSMIC satellites over the African region Ann. Geophys. (IF 1.49) Pub Date : 2020-11-24 Patrick Mungufeni; Sripathi Samireddipalle; Yenca Migoya-Orué; Yong Ha Kim
This study developed a model of total electron content (TEC) over the African region. The TEC data were obtained from radio occultation measurements done by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites. Data during geomagnetically quiet time (Kp < 3 and Dst > −20 nT) for the years 2008–2011 and 2013–2017 were binned according to local time, seasons
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A deep insight into the ion foreshock with the help of test particle two-dimensional simulations Ann. Geophys. (IF 1.49) Pub Date : 2020-11-24 Philippe Savoini; Bertrand Lembège
Two-dimensional (2D) test particle simulations based on shock profiles issued from 2D full particle-in-cell (PIC) simulations are used in order to analyze the formation processes of ions back streaming within the upstream region after interacting with a quasi-perpendicular curved shock front. Two different types of simulations have been performed based on (i) a fully consistent expansion (FCE) model
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Contribution of Meteor Flux in the Occurrence of Sporadic-E over Arabian Peninsula Ann. Geophys. (IF 1.49) Pub Date : 2020-11-24 Muhammad Mubasshir Shaikh; Govardan Gopakumar; Aisha Abdulla Alowais; Maryam Essa Sharif; Ilias Fernini
Abstract. Sporadic-E (Es) is generally associated with a thin-layered structure present in the lower ionosphere mostly consisted of metallic ions. This metallic ion layer is formed when meteors burn in the upper atmosphere resulting in the deposition of free metal atoms and ions. Many studies have attributed to the presence of Es due to metallic ion layer, specifically during the nighttime. Using data
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Mesoscale Convective Systems as a source of electromagnetic signals registered by ground-based system and DEMETER satellite Ann. Geophys. (IF 1.49) Pub Date : 2020-11-21 Karol Martynski; Jan Blecki; Roman Wronowski; Andrzej Kulak; Janusz Mlynarczyk; Rafał Iwanski
Abstract. Mesoscale Convective Systems (MCS) are especially visible in the summertime, when there is an advection of warm maritime air from the West. Advection of air masses is enriched by water vapour, which source can be found over the Mediterranean Sea. In propitious atmospheric conditions, thus significant convection, atmospheric instability or strong vertical thermal gradient, lead to the development
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Observations of precipitation energies during different types of pulsating aurora Ann. Geophys. (IF 1.49) Pub Date : 2020-11-13 Fasil Tesema; Noora Partamies; Hilde Nesse Tyssøy; Derek McKay
Pulsating aurora (PsA) is a diffuse type of aurora with different structures switching on and off with a period of a few seconds. It is often associated with energetic electron precipitation (>10 keV) resulting in the interaction between magnetospheric electrons and electromagnetic waves in the magnetosphere. Recent studies categorize pulsating aurora into three different types – amorphous pulsating
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Analysis of different propagation models for the estimation of the topside ionosphere and plasmasphere with an ensemble Kalman filter Ann. Geophys. (IF 1.49) Pub Date : 2020-11-10 Tatjana Gerzen; David Minkwitz; Michael Schmidt; Eren Erdogan
The accuracy and availability of satellite-based applications, like Global Navigation Satellite System (GNSS) positioning and remote sensing, crucially depend on the knowledge of the ionospheric electron density distribution. The tomography of the ionosphere is one of the major tools for providing links to specific ionospheric corrections and studying and monitoring physical processes in the ionosphere
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Stratospheric influence on MLT over mid-latitudes in winter by Fabry-Perot interferometer data Ann. Geophys. (IF 1.49) Pub Date : 2020-11-10 Olga S. Zorkaltseva; Roman V. Vasilyev
Abstract. In this paper, we study the response of the mesosphere and lower thermosphere (MLT) to sudden stratospheric warmings (SSWs) and the activity of stationary planetary waves (SPWs). We observe the 557.7-nm optical emission for retrieve the MLT wind, temperature with the Fabry-Perot interferometer (FPI) that has no analogues in Russia. The FPI is located at the mid-latitudes of Eastern Siberia
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Tomographic imaging of a large-scale travelling ionospheric disturbance during the Halloween storm of 2003 Ann. Geophys. (IF 1.49) Pub Date : 2020-11-03 Karl Bolmgren; Cathryn Mitchell; Talini Pinto Jayawardena; Gary Bust; Jon Bruno; Elizabeth Mitchell
The most intense ionospheric storm observed in recent times occurred between 29 and 31 October 2003. The disturbances to the high-latitude regions set off several large-scale travelling ionospheric disturbances (LSTIDs), wave-like perturbations in the ionospheric electron density. This paper investigates one particular TID on 31 October 2003 using North American Global Positioning System (GPS) receiver
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High-latitude crochet: solar-flare-induced magnetic disturbance independent from low-latitude crochet Ann. Geophys. (IF 1.49) Pub Date : 2020-11-03 Masatoshi Yamauchi; Magnar G. Johnsen; Carl-Fredrik Enell; Anders Tjulin; Anna Willer; Dmitry A. Sormakov
A solar-flare-induced, high-latitude (peak at 70–75∘ geographic latitude – GGlat) ionospheric current system was studied. Right after the X9.3 flare on 6 September 2017, magnetic stations at 68–77∘ GGlat near local noon detected northward geomagnetic deviations (ΔB) for more than 3 h, with peak amplitudes of >200 nT without any accompanying substorm activities. From its location, this solar flare effect
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An early mid-latitude aurora observed by Rozier (Béziers, 1780) Ann. Geophys. (IF 1.49) Pub Date : 2020-11-02 Chiara Bertolin; Fernando Domínguez-Castro; Lavinia de Ferri
Aurora observations are an uncommon phenomenon at low and mid latitudes that, at the end of the 18th century, were not well known and understood. Low and mid geomagnetic latitude aurora observations provide information about episodes of intense solar storms associated with flares and outstanding coronal mass ejection (CME) and about the variation of the geomagnetic field. However, for many observers
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An inter-hemispheric seasonal comparison of polar amplification using radiative forcing of a quadrupling CO2 experiment Ann. Geophys. (IF 1.49) Pub Date : 2020-10-29 Fernanda Casagrande; Ronald Buss de Souza; Paulo Nobre; Andre Lanfer Marquez
The numerical climate simulations from the Brazilian Earth System Model (BESM) are used here to investigate the response of the polar regions to a forced increase in CO2 (Abrupt-4×CO2) and compared with Coupled Model Intercomparison Project phase 5 (CMIP5) and 6 (CMIP6) simulations. The main objective here is to investigate the seasonality of the surface and vertical warming as well as the coupled
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