Browse Articles
Strong Quarterdiurnal Tides in the Mesosphere and Lower Thermosphere During the 2019 Arctic Sudden Stratospheric Warming Over Mohe, China
-  22 September 2021
Key Points
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Strong quarterdiurnal tides (QDTs) are observed in the mesosphere and lower thermosphere during the 2019 Arctic sudden stratospheric warming (SSW)
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The nonlinear interaction between tidal waves may contribute to the enhancement of the QDTs
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The effect of the 2019 Arctic SSW may play an important role in the amplification of the QDTs
Effects of Subauroral Polarization Streams on the Equatorial Electrojet During the Geomagnetic Storm on June 1, 2013
-  22 September 2021
Key Points
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The daytime counter equatorial electrojet is generated by the subauroral polarization streams (SAPS)
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The Cowling conductivity induced by SAPS plays a negligible role in the changes of equatorial electrojet
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The counter equatorial electrojet is associated with the disturbance dynamo electric field due to disturbance zonal wind
Unexpected Decrease in TW3 Amplitude During Antarctic Sudden Stratospheric Warming Events as Revealed by SD‐WACCM‐X
-  20 September 2021
Key Points
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TW3 amplitudes show an unexpected decrease in the neutral atmosphere during Antarctic sudden stratospheric warming (SSW) events as revealed by SD-WACCM-X
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The decrease in TW3 is likely due to the weakness of DW1 and derived from nonlinear wave-wave interactions
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The simultaneous decrease in the TW3 amplitudes in the ionosphere indicates neutral-ion coupling through tides during Antarctic SSW events
Simultaneous Observation of Whistler Waves and Electron Cyclotron Harmonic Waves in the Separatrix Region of Magnetopause Reconnection
-  20 September 2021
Key Points
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A very narrow band whistler wave and electron cyclotron harmonic waves are simultaneously observed in the magnetosphere separatrix region
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The electron loss-cone distributions are continuously detected while the two kinds of waves are observed
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The two kinds of waves are probably excited by the electron loss-cone instability
Cross‐ Coherence of the Outer Radiation Belt During Storms and the Role of the Plasmapause
-  17 September 2021
Key Points
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Near-relativistic electron fluxes associated with storms are highly correlated (
) cross-
outside the minimum plasmapause location
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Electron fluxes inside the minimum location of the plasmapause are also well correlated but show little correlation with fluxes outside
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During storm main and recovery phases, the electron fluxes are well correlated across all
irrespective of the plasmapause location
Ion Kappa Distribution Parameters in the Magnetosphere of the Earth at Geocentric Distances Smaller Than 20 RE During Quiet Geomagnetic Conditions
-  17 September 2021
Key Points
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Ion spectra obtained from the Time History of Events and Macroscale Interactions during Substorms satellite mission near the equatorial plane are fitted by a kappa distribution function
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Distribution of three fitting parameters (density, core energy, value of k characterizing the spectra slope at high energies) are obtained
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Region of increased k index at geocentric distances 8–10 RE is selected
Drift Orbit Bifurcations and Cross‐Field Transport in the Outer Radiation Belt: Global MHD and Integrated Test‐Particle Simulations
-  17 September 2021
Key Points
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We develop high precision test particle simulations integrated inside global magnetohydrodynamic simulations and study drift orbit bifurcations
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The resulting transport displays notable structure close to the magnetopause and differences for southward and northward interplanetary magnetic field orientations
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The convection electric field not included in previous DOB studies has a significant effect on the resultant transport characteristics
Deducing Non‐Migrating Diurnal Tides in the Middle Thermosphere With GOLD Observations of the Earth's far Ultraviolet Dayglow From Geostationary Orbit
-  16 September 2021
Key Points
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First estimates of non-migrating diurnal tides from an observational platform in geostationary orbit using GOLD
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Deduction of non-migrating tides via known phase relationships between temperature and composition
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Retrieved tidal amplitudes from GOLD observations are generally stronger than their predicted model counterparts
Reconstructing Substorms via Historical Data Mining: Is It Really Feasible?
-  13 September 2021
Key Points
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A new high-resolution B-field representation combined with dynamical data mining reveals magnetosphere behavior on the substorm-time scale
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Full cycle of magnetosphere evolution is reconstructed based on 25-year archive of satellite data and a set of ground-based activity indices
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Initial growth of the distant magnetotail current and its subsequent sudden collapse during the substorm onset are consistently reproduced
The Onset of a Substorm and the Mating Instability
-  30 September 2021
Key Points
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Growth phase arc brightening and instability and reconnection in the near-Earth tail are completely separate processes
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Auroral streamers may be low-entropy content bubbles with a flow channel attached and manifested by an Alfvenic arc
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Mating of two unconnected current sheets by a non-MHD process creates a channel for outflow of energy from the high-beta plasma layer
Diurnal UT Variation of low Latitude Geomagnetic Storms Using six Indices
-  29 September 2021
Key Points
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A striking quasi-semidiurnal pattern is observed in the UT distribution of the geomagnetic storm intensity in six low latitude indices
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Similar pattern exists in the UT variation of the computed value of the main energy input in the ring current
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The quasi-semidiurnal pattern correlates well with the angles μ and θ involved in the mechanisms of equinoctial hypothesis and RM effect
Broadband Imaging to Study the Spectral Distribution of Meteor Radio Afterglows
-  29 September 2021
Key Points
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We collected broadband spectra of 86 meteor radio afterglows (MRAs)
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The spectral index distribution of 86 events peaked at –1.73
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Spectral parameters are not correlated with the physical properties of MRAs
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The duration of the MRAs is found to correlate with other physical properties of MRAs
Saturn’s inner magnetospheric convection in the view of zebra stripe patterns in energetic electron spectra
-  29 September 2021
Key Points
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Energy-discretized electron spectra (zebra stripes) were seen in the majority of Cassini's orbits
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Zebra stripes develop within tens of hours and spread to the whole inner magnetosphere
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The electric field responsible for the stripes has an L-shell and time dependent deviation from the noon-midnight orientation
ULF Waves Observed by Lunar Prospector
-  29 September 2021
Key Points
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ULF waves near the Moon are identified above strong magnetic anomalies on the dayside over a broad frequency band of 10–60 mHz
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The solar wind protons reflected from lunar magnetic anomalies are an energy source for wave excitation through ion beam instability
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The ion beam instability driven by the reflected proton beam is a source for the observed ULF waves in the vicinity of the Moon
Energy Budgets from Collisionless Magnetic Reconnection Site to Reconnection Front
-  29 September 2021
Key Points
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Energy budgets from collisionless magnetic reconnection site to reconnection fronts are studied through two-dimensional particle-in-cell simulations
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The reconnection fronts that dominate the energy conversion are generated from the reconnection site
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Energy conversion at the well-developed reconnection front is unrelated to the reconnection site. The Poynting flux inflow is mainly converted to enthalpy flux
Jupiter’s auroral radio emissions observed by Cassini: rotational versus solar wind control, and components identification
-  29 September 2021
Key Points
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We build synthetic frequency-longitude maps of polarized Jovian auroral radio emissions, DAM, HOM and bKOM
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Jovian HOM and DAM are dominantly rotation-modulated, bKOM dominantly solar wind-modulated
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HOM appears primarily connected to decameter sources from the dusk side of the Jovian magnetosphere
Electron Heat Flux in the Solar Wind: Generalized Approaches to Fluid Transport with a Variety of Skewed Velocity Distributions
-  28 September 2021
Key Points
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Understanding coronal heating and solar wind acceleration requires an accurate description of heat conduction beyond Spitzer-Härm theory
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Fluid-moment models of parallel electron heat conduction are constructed using skewed, positive-definite velocity distributions
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Both analytic models and fits to in situ data can be used to constrain parameters of closed-form solutions for the collisionless heat flux
Complementary and Catalytic Roles of Man‐Made VLF Waves and Natural Plasma Waves in the Loss of Radiation Belt Electrons
-  27 September 2021
Key Points
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Man-made VLF waves mainly reduce hundreds of keV electrons in inner belt, but cannot effectively remove MeV electrons in slot region
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Natural hiss and LGWs mainly remove the MeV electrons in slot region, but do not affect the hundreds of keV electron in inner belt
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Man-made VLF waves can promote the loss of the MeV electrons at large pitch angles in slot region when existence of natural hiss or LGWs
Sensitivity of Upper Atmosphere to Different Characteristics of Flow Bursts in the Auroral Zone
-  27 September 2021
Key Points
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Neutral density perturbations due to a midnight flow burst are most sensitive to the flow burst scale-size
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Neutral density perturbation magnitudes due to flow bursts at different local times depend on the background conditions
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Single- and two-cell flow bursts induce similar neutral density perturbation patterns
NRLMSISE‐00 empirical model of the atmosphere: Statistical comparisons and scientific issues
- Journal of Geophysical Research: Space Physics
-  SIA 15-1-SIA 15-16
-  24 December 2002
What is a geomagnetic storm?
- Journal of Geophysical Research: Space Physics
-  5771-5792
-  1 April 1994
Solar wind spatial scales in and comparisons of hourly Wind and ACE plasma and magnetic field data
- Journal of Geophysical Research: Space Physics
-  16 February 2005
Modeling the dynamics of the inner magnetosphere during strong geomagnetic storms
- Journal of Geophysical Research: Space Physics
-  15 March 2005
Geospace Environmental Modeling (GEM) Magnetic Reconnection Challenge
- Journal of Geophysical Research: Space Physics
-  3715-3719
-  1 March 2001
Magnetic loop behind an interplanetary shock: Voyager, Helios, and IMP 8 observations
- Journal of Geophysical Research: Space Physics
-  6673-6684
-  1 August 1981
The ionospheric disturbance dynamo
- Journal of Geophysical Research: Space Physics
-  1669-1686
-  1 April 1980
Collision frequency of artificial satellites: The creation of a debris belt
- Journal of Geophysical Research: Space Physics
-  2637-2646
-  1 June 1978
Magnetopause location under extreme solar wind conditions
- Journal of Geophysical Research: Space Physics
-  17691-17700
-  1 August 1998
Effect of the altitudinal variation of the gravitational acceleration on the thermosphere simulation
- Journal of Geophysical Research: Space Physics
-  4 September 2008
Possible modification of the cooling index of interstellar helium pickup ions by electron impact ionization in the inner heliosphere
- Journal of Geophysical Research: Space Physics
-  7142-7150
-  7 September 2014
Key Points
- The influence of electron impact ionization is negligible
- Its influence is also small even in the compressions
A Low Signal Detection of X‐Rays From Uranus
- Journal of Geophysical Research: Space Physics
-  31 March 2021
Key Points
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A Chandra ACIS observation reveals a 10.3 sigma detection of X-rays from Uranus with a probability of chance occurrence of 10−6–10−7
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Uranus' X-rays are concentrated between 0.6 and 1.1 keV, consistent with emission observed from Jupiter and Saturn
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The X-ray fluxes seem to exceed scattered solar emission alone, which may suggest X-ray aurora and/or X-ray fluorescence from the rings
Earth's Van Allen Radiation Belts: From Discovery to the Van Allen Probes Era
- Journal of Geophysical Research: Space Physics
-  8319-8351
-  23 November 2019
Key Points
- A brief historical background on the discovery of the Van Allen radiation belts and their response to solar activity is introduced
- Recent advances in understanding mechanisms responsible for radiation belt electron acceleration, transport, and loss are reviewed
- Outstanding challenges for developing future radiation belt models are summarized
Plain Language Summary
Discovery of the Earth's Van Allen radiation belts by instruments flown on Explorer 1 in 1958 was the first major discovery of the Space Age. The dynamic properties of trapped outer zone electrons and the outer boundary of the inner zone proton population, along with source populations, have recently been studied in great detail by instruments on National Aeronautics and Space Administration's Van Allen Probes spacecraft, as well as other data sources like operational spacecraft designed for navigation and terrestrial weather forecasting. The vulnerability of the myriad of spacecraft that is strongly affected by space weather disruptions, as compared to 1958, has motivated the radiation belt community to develop essential improved models for forecasting the space environment we will inhabit in the 21st century and evaluate its impacts on our technological society. In this paper, we provide a review on historical background and recent advances in understanding and modeling acceleration, transport, and loss processes of energetic particles in the Earth's Van Allen radiation belts, followed by outstanding challenges for developing future radiation belt models. The findings on the fundamental physics of the Van Allen radiation belts potentially provide insights into understanding energetic particle dynamics at other magnetized planets in the solar system, exoplanets throughout the universe, as well as in astrophysical and laboratory plasmas. Given the potential Space Weather impact of radiation belt variability on technological systems, these new radiation belt models are expected to play a critical role in our technological society in the future much as meteorological models do today.
NRLMSISE‐00 empirical model of the atmosphere: Statistical comparisons and scientific issues
- Journal of Geophysical Research: Space Physics
-  SIA 15-1-SIA 15-16
-  24 December 2002
Magnetic Reconnection in the Space Sciences: Past, Present, and Future
- Journal of Geophysical Research: Space Physics
-  15 December 2019
Key Points
- Magnetic reconnection is a key energy conversion and transport process in plasmas
- There has been recent, considerable, research progress understanding how reconnection works
- Many exciting research challenges await, while we can reap the benefits of our new understanding
Plain Language Summary
In space, huge amounts of energy are released explosively by a mysterious mechanism: magnetic reconnection. Reconnection can abruptly convert energy stored in magnetic fields to energy in charged particles, and power such diverse phenomena as solar and stellar flares, magnetic storms and aurorae in near-Earth space, and major disruptions in magnetically confined fusion devices. It is behind many of the dangerous effects associated with space weather, including damage to satellites, endangering astronauts, and impacting the power grid and pipelines. Understanding reconnection enables us to quantitatively describe and predict these magnetic explosions. Therefore, magnetic reconnection has been at the forefront of scientific interest for many years, and will be for many more. Measuring reconnection is incredibly difficult. However, recently scientists have been able to peek into its machinery. Combining measurements from NASA's Magnetospheric Multiscale mission with supercomputer modeling, scientists have now been able to analyze the inner workings of this elusive mechanism. Even though open questions remain, this new understanding has broad implications. Here, we describe magnetic reconnection, where it plays a role, its impacts on society, and what we now know about it. We point to future research challenges, including implications and the utility of our recently developed knowledge.
Correcting the Dst index: Consequences for absolute level and correlations
- Journal of Geophysical Research: Space Physics
-  24 August 2006
Editorial: Reviewer selection process and new areas of expertise in GEMS
- Journal of Geophysical Research: Space Physics
-  5566-5570
-  23 May 2016
Key Points
- Methods for selecting potential reviewers for manuscripts are described, including filtering user Areas of Expertise in the GEMS database
- The Journal Editors have just added 18 new Areas of Expertise in GEMS, increasing the list by 33% to 73 entries
- Space physicists are urged to update their GEMS profiles, especially their Areas of Expertise, to improve potential reviewer selection
Diurnal nonmigrating tides from TIMED Doppler Interferometer wind data: Monthly climatologies and seasonal variations
- Journal of Geophysical Research: Space Physics
-  9 September 2006
Challenges to Understanding the Earth's Ionosphere and Thermosphere
- Journal of Geophysical Research: Space Physics
-  27 February 2020
Key Points
- Winds and currents dependent on external drivers and internal processes need improved descriptions
- Coupling to the magnetosphere should include hemispheric differences in energy and mass flow
- Formation and evolution of multiscale structures require detailed investigation
Plain Language Summary
The ionosphere is the region of Earth's upper atmosphere made up of a mixture of charged and neutral gases between approximately 50 and 1,000 miles (80–1,600 km) above the Earth's surface. Sandwiched between the lower atmosphere and the magnetosphere, the ionosphere reacts to weather and climate near the Earth's surface and to eruptions and sunspot activity on the Sun. The ionosphere absorbs the harmful radiation from the Sun and determines the fidelity of all radio communication, navigation, and surveillance transmissions through it. It is part of a complex, coupled system that changes on scales from meters to the planetary radius, and from seconds to decades. Understanding how the behavior of this region is controlled, by internal interactions and by the external regions to which it is coupled, is the preeminent challenge for the next generation of scientists. These challenges in understanding Earth's ionosphere are associated with deciphering the many changes in neutral and plasma density and their relationships to the coupling with the Earth's lower atmosphere, the generation and flow of currents within the region, and the coupling to the magnetosphere. Addressing these challenges requires advances in observing the composition and dynamics of the neutral particles and simultaneous observations of the charged particles, as well as the particles and field-aligned current describing the coupling of the ionosphere to the magnetosphere. Additionally, our modeling capability must advance to include better descriptions of the processes affecting the ionosphere and thermosphere region and to incorporate coupling with the regions below and above at smaller spatial and temporal scales.