The Neutral Gas and Ion Mass Spectrometer of the Mars Atmosphere and Volatile Evolution provides a large data set to explore the ion composition and structure of the Martian ionosphere. Here the dayside measurements are used to investigate the minor ion density profiles with distinctive peaks above 150 km, revealing a systematic trend of decreasing peak altitude with increasing ion mass. We specifically

Jupiter displays many distinct auroral structures, among which auroral dawn storms and auroral injections are often observed contemporaneously. However, it is unclear if the contemporaneous nature of the observations is a coincidence or part of an underlying physical connection. We show six clear examples from a recent Hubble Space Telescope campaign (GO‐14634) that each display both auroral dawn storms

Using a three‐dimensional (3D) global‐scale hybrid code, the Magnetospheric Multiscale (MMS) reconnection event around 02:13 UT on 18 November 2015, highlighted in the Geospace Environment Modeling (GEM) Dayside Kinetic Challenge, is simulated, in which the interplanetary magnetic field (IMF) points southward and the geomagnetic field has a −27∘ dipole tilt angle. Strong southward plasma jets are found

Prompt penetration of convection/overshielding electric fields to equatorial and low‐latitudes during the southward/northward turnings of interplanetary magnetic field (IMF Bz) have been widely studied in the literature. The other types of penetration electric fields due to sudden changes in the solar wind dynamic pressure, IMF By and during the onset of substorms have also been recently reported.

A comprehensive analysis on the ionospheric planetary wave activity is undertaken using eight years of ionosonde data at Trivandrum (8.5o N, 77o E), a dip equatorial station. The study reveals that the dominant planetary wave is of 16‐ day type and its strength is maximum in winter solstice/autumnal equinox and minimum in summer solstice in high solar activity conditions. In low solar activity years

The goal of the present study is to observationally test the idea that the substorm current wedge (SCW) is an ensemble of wedgelets, meso‐scale current systems that correspond to plasma‐sheet flow channels. According to this hypothesis, the SML index, SuperMAG equivalent to the AL index, represents a single particular wedgelet at a given time, whereas mid‐latitude positive bays are a sum of the remote

Earth’s slot region, lying between the outer and inner radiation belts, has been identified as due to a balance between inward radial diffusion and pitch angle (PA) scattering induced by waves. However, recent satellite observations and modeling studies indicate that CRAND may also play a significant role in energetic electron dynamics in the slot region. In this study, using a drift‐diffusion‐source

Ionospheric F region bottom‐type irregularity layer has been frequently detected at equatorial latitude and regarded as a possible precursor of equatorial backscatter plumes producing scintillations. In this study, the VHF radar observations of ionospheric F region bottom‐type irregularity layers and plasma plumes over the low latitude station Sanya (18.4°N, 109.6°E, dip lat. 12.8°N) during the equinoctial

The Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) mission provided long‐term measurements of 10s of MeV inner belt (L<2) protons (1992‐2009) as did the Polar‐orbiting Operational Environmental Satellite‐18 (POES‐18, 2005‐present). These long‐term measurements at low‐Earth orbit (LEO) showed clear solar cycle variations which anti‐correlate with sunspot number. However the magnitude

To understand magnetosphere‐ionosphere conditions that result in thermal emission velocity enhancement (STEVE) and subauroral ion drifts (SAID) during the substorm recovery phase, we present substorm aurora, particle injection, and current systems during two STEVE events. Those events are compared to substorm events with similar strength but without STEVE. We found that the substorm surge and intense

Quasi‐thermal noise (QTN) spectroscopy has been extensively used as an accurate tool to measure electron density and temperature in space plasmas. If the antenna length to radius ratio is sufficiently large, a typical measured spectrum clearly shows a resonance at the electron plasma frequency and a lower frequency plateau that quantify the electron distributions. The Wind spacecraft, with its long

Although the postmidnight‐to‐dawn sector of the auroral ionosphere contains interesting dynamic phenomena that may significantly impact the magnetosphere‐ionosphere‐thermosphere system, it has been much less studied than the dusk‐to‐premidnight sector. We discuss a dynamic phenomenon in the postmidnight‐to‐dawn sector of the auroral oval, eastward fast flows mainly within the expanse of the Region

Range‐time‐intensity (RTI) plots of 50 MHz radar backscatter detected at Jicamarca from the 150‐km region of the equatorial ionosphere exhibit necklace‐shaped multilayered structures first reported by Kudeki and Fawcett (1993, https://doi.org/10.1029/93GL01256). The backscatter layers also exhibit quasi‐periodic intensity fluctuations with periods of about 5–15 min and are separated from adjacent layers

Though the Kelvin‐Helmholtz instability (KHI) has been extensively observed in the mesosphere, where breaking gravity waves produce the conditions required for instability, little has been done to describe quantitatively this phenomenon in detail in the mesopause and lower thermosphere, which are associated with the long‐lived shears at the base of this statically stable region. Using trimethylaluminum

Solar coronal mass ejections (CMEs) are sometimes deflected during their propagation. This deflection may be the consequence of an interaction between the CME and the ambient coronal field, for example, a coronal hole, or the solar wind. The coronal magnetic field configuration is computed from daily synoptic maps of magnetic field from SOHO/MDI and SDO/HMI using a Potential Field Source Surface model

The Van Allen Probes Mission consists of two identical spacecraft flying in highly elliptical orbits, with perigee altitudes originally near 600 km. During the low‐altitude periods of the orbits, the spacecrafts are immersed in a region of high‐density atomic oxygen. Atomic oxygen is known to change and degrade the properties of spacecraft surfaces (Banks et al., 2004), such as those of the Van Allen

The existence of Birkeland magnetic field‐aligned current (FAC) system was proposed more than a century ago, and it has been of immense interest for investigating the nature of solar wind‐magnetosphere‐ionosphere coupling ever since. In this paper, we present the first application of deep learning architecture for modeling the Birkeland currents using data from the Active Magnetosphere and Planetary

The Io plasma torus is thought to lie in Jupiter's centrifugal equator, a location that depends on Jupiter's rotation and magnetic field. Yet previous observations and predictions of the location of the Io plasma torus are inconsistent. Here we test the hypothesis that the Io plasma torus lies in the centrifugal equator by comparison of observations by Juno radio occultations to predictions derived

The first global atmospheric model of Ni (WACCM‐Ni) has been developed to understand recent observations of the mesospheric Ni layer by ground‐based resonance lidars. The three components of the model are: the Whole Atmospheric Community Climate Model (WACCM6); a meteoric input function derived by coupling an astronomical model of dust sources in the solar system with a chemical meteoric ablation model;

Auroral arcs and diffuse auroras are common phenomena at high latitudes, though characteristics of their source plasma and fields have not been well understood. We report the first observation of fields and particles including their pitch‐angle distributions in the source region of auroral arcs and diffuse auroras, using data from the Arase satellite at L  ~ 6.0–6.5. The auroral arcs appeared and expanded

The largest moon in the solar system, Ganymede, is the only moon known to possess a strong intrinsic magnetic field and a corresponding magnetosphere. Using the latest version of Space Weather Modeling Framework (SWMF), we study the upstream plasma interactions and dynamics in this sub‐Alfvénic system. Results from the Hall magnetohydrodynamics (MHD) and the coupled MHD with embedded particle‐in‐cell

On 17th January 2013, relativistic electron precipitation (REP) was observed on Balloon Array for Radiation Belt Relativistic Electron Losses (BARREL) payloads, National Oceanic and Atmospheric Administration Polar orbiting Operational Environmental Satellites (NOAA POES) and European Space Agency (ESA) MetOp between 2:44 to 15:04 hrs UT, scattered across dusk to early morning magnetic local time (MLT)

It is now well‐established through multiple event and statistical studies that the solar wind at 1 AU contains contains periodic, mesoscale (L ~100‐1000$ Mm) structures in the proton density. Composition variations observed within these structures and remote sensing observations of similar structures in the young solar wind indicate that at least some of these periodic structures originate in the solar

Imaging is one of the essential techniques to observe the astronomical structures. While analyzing the observed images, it is a challenge in many scientific fields to reconstruct the 3‐dimensional structures from 2‐dimensional image(s). This report discusses this challenge in the context of reconstructing the structure of the Earth's magnetosphere from the X‐ray image and presents a new technique.

We present a study concerning a space weather event on 25–29 August 2018, accounting for its ionospheric and magnetic signatures at low latitudes and midlatitudes. The effects of a storm in several longitudinal sectors (Asia, Africa, America, and the Pacific) have been analyzed using various parameters such as total electron content (TEC), geomagnetic field, and column [O/N2] ratio. Positive ionospheric

The Parker Solar Probe successfully makes electric field measurements over the frequency range of DC‐100 Hz, thanks to the remarkable symmetry of the antennas with respect to sunlight and the mostly radial magnetic field. Calibration of the electric field measurement is described. Sampled electric and magnetic field data are utilized to determine wave modes of whistlers and Alfven‐ion‐cyclotron waves

Ultralow Frequency (ULF) waves are electromagnetic pulsations observed throughout the magnetosphere driven by processes both external and internal to the magnetosphere. Within the magnetosphere, discrete and broadband ULF wave activity can couple to the local plasma via coherent or stochastic wave‐particle interactions. These wave‐particle interactions can lead to dynamic changes in local plasma including

We investigate how initially high‐m, poloidal Alfvén waves evolve using a numerical model solving the ideal, cold, linear magnetohydrodynamic (MHD) equations in a 2D dipole coordinate system. The curved magnetic geometry provides a key difference between the poloidal and toroidal Alfvén frequencies of any one field line. A polarisation rotation from poloidal towards toroidal predicted from the Cartesian

In this paper, we present a systematic study on the characteristics and evolution of the F 3 layer using the Jicamarca incoherent scatter radar (ISR) observations made during 2014–2018. These results are also compared with those obtained from collocated digisonde observations in an effort to understand the F 3 layer in more detail. The purpose of the comparison is twofold: first is to see how the digisonde

This paper presents observations of polar cap arc substructure down to scale sizes of meters and temporal resolution of milliseconds. Two case studies containing polar cap arcs occurring over Svalbard are investigated. The first occurred on 4 February 2016 and is consistent with formation on closed field lines; the second occurred on 15 December 2015 and is consistent with formation on open field lines

A complex daytime sporadic E (E s ) case with extremely high critical frequency (f o E s ) was observed over the low latitude of China on 19 May 2018. Simultaneous observational results from two very high frequency (VHF) radars, two ionosondes, and multiple Global Navigation Satellite System total electron content and scintillation receivers are analyzed to investigate the evolution of the complex

Polar cap and auroral oval areas are presented for the period 1900–2015 using a model of the magnetosphere and the International Geomagnetic Reference Field Version 12 (IGRF‐12) model for the geomagnetic field. The effect of the main field long‐term changes is addressed considering steady interplanetary conditions. Until ~1940 both northern and southern polar cap areas increased with time, consistent

This paper examined the secular displacement of the dip equator and the geomagnetic poles as well as the variations of the global magnetic inclination and declination angles using magnetometer measurements onboard different low‐earth‐orbit (LEO) satellite. The secular variation of the dip equator and geomagnetic poles has different impacts on different applications – from affecting the long‐term characterization

We present the first systematic analysis of global ionospheric disturbance current systems caused by multiple processes of solar and magnetospheric origin, including reorientations of the interplanetary magnetic field (IMF), sudden changes in the solar wind dynamic pressure, magnetospheric sawtooth substorms, and ultra‐low frequency (ULF) waves. Measurements from global magnetometer networks are used

The ionospheric responses to the total solar eclipse on 2 July 2019 over low latitudes in southern South America are presented. Ionosonde observations were used within the totality path at La Serena (LS: 29.9°S, 71.3°W) and at Tucumán (TU: 26.9°S, 65.4°W) and Jicamarca (JI: 12.0°S, 76.8°W), with 85 and 52% obscuration, respectively. Total electron content (TEC) estimations over the South American continent

In this paper, we investigate the latitudinal and longitudinal variations of the disturbance ionospheric current during 12 geomagnetic storms with Dst ranging between ‐50 to ‐130 nT. For this purpose, data from 15 geomagnetic stations along three longitudinal sectors at 70°E, 77°E and 93°E, ranging from mid to equatorial latitudes in both hemispheres are analyzed. Our study reveals the pattern of PP

With a linear theoretical model, we have investigated the properties of whistler waves excited by anisotropic hot electrons with a drift velocity parallel to the background magnetic field, which is usually neglected in previous studies. It is found that a finite drift velocity can significantly change the properties of excited whistler waves, resulting in distinct properties for parallel and antiparallel

It has been noticed recently that the EIA in the Brazilian eastern, middle, and western sectors present significant longitudinal variability within a short separation due to the presence of typical magnetic field structure over South America. Therefore, the main motivation of this study is to investigate day‐to‐day and month‐to‐month characteristics of the equatorial ionization anomaly (EIA) in 3 closely

Whistler and electrostatic electron cyclotron harmonics (ECH) waves are responsible for scattering and precipitating the energetic plasma‐sheet electrons that drive the diffuse aurora. These primary electrons with energies in the keV range, simultaneously precipitating in magnetically conjugate regions, produce the secondary electron population and can be reflected by the atmosphere back through the

The flux of energetic electrons in the outer radiation belt shows a high variability. The interactions of electrons with very low frequency (VLF) chorus waves play a significant role in controlling the flux variation of these particles. Quantifying the effects of these interactions is crucially important for accurately modeling the global dynamics of the outer radiation belt and to provide a comprehensive

We investigate mechanisms of wave particle heating of ionospheric O+ ions resulting from broadband extremely low frequency (BBELF) waves using numerical test particle simulations that take into account ion‐neutral collisions, in order to explain observations from the Enhanced Polar Outflow Probe (e‐POP) satellite at low altitudes (∼400 km) (Shen et al., 2018, https://doi.org/10.1002/2017JA024955).

We evaluate energetic electron scattering in pitch angle and energy using realistic magnetic field and density models due to whistler mode chorus waves in Jupiter's magnetosphere and study their dependences on various wave and background parameters. We calculate the bounce‐averaged diffusion coefficients by considering the latitudinal variation of total electron density and ambient magnetic field intensity

An Ionospheric Observational Network for Irregularity and Scintillation in East and Southeast Asia (IONISE) is developed to identify and study the short‐term and fine‐scale ionospheric variations over China. The IONISE network mainly includes three crossed chains of Beidou geostationary satellite total electron content (TEC)/scintillation receivers along 110°E, 23°N, and 40°N respectively, multistatic

The increasing amount of the Global Navigation Satellite System (GNSS) ground receivers provides extremely abundant data resource to ionospheric community. In present paper, a hybrid data assimilation method is proposed to derive the global ionosphere maps (GIM) using the GNSS measurements. This method can balance the weights of background information from the International Reference Ionosphere model

Using a magnetohydrodynamic simulation of magnetotail reconnection, flow bursts, and dipolarization, we further investigate the current diversion and energy flow and conversion associated with the substorm current wedge (SCW) or smaller‐scale wedgelets. Current diversion into both Region 1 (R1) and Region 2 (R2) sense systems is found to happen inside (that is, closer to the center of the flow burst)

Throat auroras frequently observed near local noon have been confirmed to correspond to magnetopause indentations, but the generation mechanisms for these indentations and the detailed properties of throat aurora are both not fully understood. Using all‐sky camera and magnetometer observations, we reported some new observational features of throat aurora as follows. (1) Throat auroras can occur under

The ratio of O number density to N2 number density (O/N2) is an important parameter to describe thermospheric composition changes and its effects on the ionosphere. Based on Global Ultraviolet Imager (GUVI) limb measurements, we investigate the seasonal behaviors of O/N2 volume density ratio on different constant pressure levels during geomagnetically quiet periods. The global O/N2 shows the prominent

Euler potentials of the Earth's dipole magnetic field with field‐aligned currents are found. The results generalize ones obtained earlier for systems of plane currents parallel to an ambient uniform magnetic field. A real current system corresponding to an observed increase of the magnetic field measured by a low‐altitude spacecraft is used in this modeling. Parameters of charged particle trajectories

By utilizing magnetic field measurements collected by CHAMP during the years 2001–2009, average characteristics of nighttime ionospheric zonal currents at middle and low latitudes are investigated. We provide for the first time the detailed dependencies of these currents on location, local time, season, and the level of solar activity. The main results obtained are (1) the nighttime zonal ionospheric

Reliable quantification of the global, and time‐dependent structure of the Earth's outermost atmosphere, a vast region known as the exosphere, has long been elusive, owing mainly to the sparse spatial and temporal sampling afforded by exospheric sensing platforms deployed to date. In this paper, we introduce new observing schemes that overcome these historical limitations and enable high‐fidelity,

We report results from a study of two consecutive Martian years of imaging observations of nitric oxide ultraviolet nightglow by the Imaging Ultraviolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile Evolution (MAVEN) mission spacecraft. The emission arises from recombination of N and O atoms in Mars' nightside mesosphere. The brightness traces the reaction rate as opposed to the abundance

Many modern outer radiation belt models simulate the long‐time behavior of high‐energy electrons by solving a three‐dimensional Fokker‐Planck equation for the drift‐ and bounce‐averaged electron phase space density that includes radial, pitch‐angle, and energy diffusion. Radial diffusion is an important process, often characterized by a deterministic diffusion coefficient. One widely used parameterization

We present observations of broadband (∼10–50 mHz) Pc3–Pc4 waves on 4 January 2014. The waves were detected on the dayside simultaneously in a compressional component (δ B z ) at the Radiation Belt Storm Probes A (RBSP‐A) in the inner magnetosphere and in the north‐south component (δ H ) on the ground at a low‐latitude Bohyun (BOH) station (L  = 1.3) during an interval of small interplanetary magnetic

In this study we investigate two distinct loss mechanisms responsible for the rapid dropouts of radiation belt electrons by assimilating data from Van Allen Probes A and B and Geostationary Operational Environmental Satellites (GOES) 13 and 15 into a 3‐D diffusion model. In particular, we examine the respective contribution of electromagnetic ion cyclotron (EMIC) wave scattering and magnetopause shadowing

The fractional mass uncertainty of linear, foil‐based time‐of‐flight space instruments is affected by the energy, path length, and timing uncertainties. Carbon foils are typically used in time‐of‐flight instruments to generate secondary electrons, but carbon foils also add unwanted effects to the instrument response. We present a complete characterization that studies the extent to which carbon foils

The development of habitable conditions on Earth is tightly connected to the evolution of its atmosphere, which is strongly influenced by atmospheric escape. We investigate the evolution of the polar ion outflow from the open field line bundle, which is the dominant escape mechanism for the modern Earth. We perform Direct Simulation Monte Carlo (DSMC) simulations and estimate the upper limits on escape

In this paper, we derive a new drift‐kinetic method for estimating gradients in the plasma properties through a velocity space distribution at a single point. The gradients are intrinsically related to agyrotropic features of the distribution function. This method predicts the gradients in the magnetized distribution function and can predict gradients of arbitrary moments of the gyrotropic background

No abstract is available for this article.

In this paper, we study on the precursor seed structures well before the prospective occurrence of equatorial plasma bubble (EPB). We use the scanning mode observations made by the 30‐MHz Gadanki Ionospheric Radar Interferometer for estimating interbubble spacing and high time resolution observations made by a collocated digisonde for inferring horizontal wavelength of wave‐like variations prior to

In the ring current dynamics, various loss mechanisms contribute to the ring current decay, including losses to the upper atmosphere through particle precipitation. This study implements the field line curvature (FLC) scattering mechanism in a kinetic ring current model and investigates its role in precipitating ions into the ionosphere during the 17 March 2013 storm. Simulation results indicate that