A5028446171- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Earthquake Detection and Analysis
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Planetary Science and Exploration
- Dust and Plasma Wave Phenomena
- Atmospheric Ozone and Climate
- Laser-induced spectroscopy and plasma
- Geophysics and Gravity Measurements
- Atomic and Subatomic Physics Research
- GNSS positioning and interference
- Magnetic Field Sensors Techniques
- Seismic Waves and Analysis
- Space Satellite Systems and Control
- Geophysics and Sensor Technology
- Space Science and Extraterrestrial Life
- Mass Spectrometry Techniques and Applications
- Ocean Waves and Remote Sensing
- Particle accelerators and beam dynamics
- Methane Hydrates and Related Phenomena
- earthquake and tectonic studies
- Cold Atom Physics and Bose-Einstein Condensates
Swedish Institute of Space Physics
2015-2024
Uppsala University
2003-2024
John Wiley & Sons (United States)
2016-2018
Charles River Laboratories (Netherlands)
2016-2018
Space Science Institute
2018
Aalto University
2016
Institut de Recherche en Astrophysique et Planétologie
2015
Umeå University
1985-2011
Massachusetts Institute of Technology
1989-2011
University of Electro-Communications
2008
[1] Two dipolarization front (DF) structures observed by Cluster in the Earth midtail region (XGSM ≈ −15 RE), showing respectively feature of Fermi and betatron acceleration suprathermal electrons, are studied detail this paper. Our results show that dominates inside a decaying flux pileup (FPR), while growing FPR. Both FPRs associated with DF can be distinguished examining whether peak bursty bulk flow (BBF) is co-located (decaying) or behind (growing). routinely caused shrinking length...
Abstract Magnetic reconnection—the process responsible for many explosive phenomena in both nature and laboratory—is efficient at dissipating magnetic energy into particle energy. To date, exactly how this dissipation happens remains unclear, owing to the scarcity of multipoint measurements “diffusion region” sub‐ion scale. Here we report such a measurement by Cluster—four spacecraft with separation 1/5 ion We discover numerous current filaments nulls inside diffusion region reconnection,...
Abstract. Highlights are presented from studies of the electric field data various regions along Cluster orbit. They all point towards a very high coherence for phenomena recorded on four spacecraft that separated by few hundred kilometers structures over whole range apparent frequencies 1 mHz to 9 kHz. This presents completely new opportunities study spatial-temporal plasma magnetosphere out solar wind. A probe environment was constructed CLUSTER experiment now produces unprecedented...
Measurements from the Cluster spacecraft of electric fields, magnetic and ions are used to study structure dynamics reconnection region in tail at distances ∼18 R E near 22.4 MLT on 1 October 2001. This paper focuses measurements large amplitude normal component field observed ion decoupling x‐line, associated potential drops across current sheet, role electrostatic ballistic acceleration sheet. The thinnest sheet during this interval was bifurcated into a pair sheets measured width...
Large‐amplitude (up to ∼50 mV/m) solitary waves, identified as electron holes, have been observed during waveform captures on two of the four Cluster satellites several plasma sheet encounters that passage a magnetotail reconnection x line. The holes were seen near outer edge sheet, within and density cavity, at distances order few ion inertial lengths from center current sheet. occur intervals when there narrow beams but not distributions more isotropic or contained broad in pitch angle....
Fast vertical flapping oscillations of the plasma sheet have been observed by Cluster on September 26, 2001. The motion had speeds exceeding 100 km/s, an amplitude in excess 1 R E and a quasiperiod ∼3 min. current was mostly tilted Y ‐ Z plane (with tilt sometimes 45°). waves properties kink mode propagated toward dusk flank. allowed to probe structure sheet. Three different methods gave consistent evidence bifurcated cross‐tail with about half all concentrated two sheets (each ∼500–1000 km...
Observations obtained by the Freja satellite at altitudes around 1700 km in high‐latitude magnetosphere are used to study ion energization perpendicular geomagnetic field. Investigations of ions, electrons, plasma densities, electric and magnetic wave fields, field‐aligned currents O + heating mechanisms. Three events studied detail, 20 a detailed statistical study. More than 200 classified as belonging one four major types ordered function local time. The most common associated with...
Magnetic reconnection leads to energy conversion in large volumes space but is initiated small diffusion regions. Because of the sizes regions, their crossings by spacecraft are rare. We report four-spacecraft observations a region encounter at Earth's magnetopause that allow us reliably distinguish spatial from temporal features. find stable on ion time and length scales agreement with numerical simulations. The electric field normal current sheet balanced Hall term generalized Ohm's law,...
We report in situ observations by the Cluster spacecraft of wave-particle interactions a magnetic flux pileup region created reconnection outflow jet Earth's magnetotail. Two distinct regions wave activity are identified: lower-hybrid drift waves at front edge and whistler-mode inside region. The locally generated electron temperature anisotropy, provide evidence for ongoing betatron energization caused pileup. cause fast pitch-angle scattering electrons isotropization distribution, thus...
Spacecraft potential measurements by the EFW electric field experiment on Cluster satellites can be used to obtain plasma density estimates in regions barely accessible other type of experiments. Direct calibrations as a function measured difference between spacecraft and probes carried out solar wind, magnetosheath, plasmashere use CIS ion WHISPER electron measurements. The photoelectron characteristic (photoelectrons escaping current balance with collected ambient electrons) calculated...
The Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe (LP) sensor observed the cold plasma environment around Titan during first two flybys. data show that conditions in Saturn's magnetosphere affect structure dynamics deep ionosphere of Titan. maximum measured ionospheric electron number density reached 3800 per cubic centimeter near closest approach, a complex chemistry was indicated. temperature profiles are consistent with heat conduction from hotter wake. escape flux estimated...
Using Cluster data, we investigate the electric structure of a dipolarization front (DF) – ion inertial length ( c/ω pi ) scale boundary in Earth's magnetotail formed at edge an earthward propagating flow with reconnected magnetic flux. We estimate current density and electron pressure gradient throughout DF by both single‐spacecraft multi‐spacecraft methods. Comparison results from two methods shows that analysis, which is capable resolving detailed boundary, can be applied for study. Based...
Dipolarization fronts (DFs) are frequently detected in the Earth's magnetotail from X GSM = −30 R E to −7 . How these DFs formed is still poorly understood. Three possible mechanisms have been suggested previous simulations: (1) jet braking, (2) transient reconnection, and (3) spontaneous formation. Among three mechanisms, first has verified by using spacecraft observation, while second third not. In this study, we show Cluster observation of inside reconnection diffusion region. This...
The occurrence rate of earthward‐propagating dipolarization fronts (DFs) is investigated in this paper based on the 9 years (2001–2009) Cluster 1 data. For first time, we select DF events by fitting characteristic increase B z using a hyperbolic tangent function. 303 DFs are found; they have average duration 4 s and 8 nT. maximum at Z GSM ≈ 0 r 15 R E with one event occurring every 3.9 hours, where distance to center Earth XY plane. can be explained steep large near central current sheet,...
We examine the pitch angle distribution (PAD) of suprathermal electrons (>40 keV) inside flux pileup regions (FPRs) that are located behind dipolarization fronts (DFs), in order to better understand particle energization mechanisms operating therein. The 303 earthward‐propagating DFs observed during 9 years (2001–2009) by Cluster 1 have been analyzed and divided into two groups according differential fluxes >40 keV FPR. One group, characterized low ( F < 500/cm 2 · s sr keV),...
Simultaneous measurements of electromagnetic fields and particle distributions, measured during the crossing by Swedish spacecraft Viking an auroral kilometric radiation (AKR) source, are presented. It is shown that AKR generated within acceleration region characterized upward directed parallel electric field, as evidenced its signature on proton electron distributions. From observations inside source it clear potential drop below produces moving field‐aligned ion beams a depletion in...
Abstract Electromagnetic ion cyclotron (EMIC) waves are an important mechanism for particle energization and losses inside the magnetosphere. In order to better understand effects of these on dynamics, detailed information about occurrence rate, wave power, ellipticity, normal angle, energy propagation angle distributions, local plasma parameters required. Previous statistical studies have used in situ observations investigate distribution magnetic time versus L‐shell (MLT‐L) frame within a...
Abstract. We report on the evolution of dipolarization and associated disturbances near-Earth current sheet during a substorm 27 October 2007, based upon Cluster multi-point, multi-scale observations night-side plasma at X~−10 RE. Three events were observed accompanied by activations ground magnetograms 09:07, 09:14, 09:22 UT. found that all these consist two types signatures: (1) Earthward moving pulse, which is enhanced rapid flux transport followed with decrease in BZ local density,...
Ions with energies less than tens of eV originate from the Terrestrial ionosphere and several planets moons in solar system. The low energy indicates origin plasma but also severely complicates detection positive ions onboard sunlit spacecraft at higher altitudes, which often become positively charged to Volts. We discuss some methods observe low‐energy ions, including a recently developed technique based on wake behind supersonic flow. Recent results this show that typically dominate...
We examine traversals on 20 November 2001 of the equatorial magnetopause boundary layer simultaneously at ∼1500 magnetic local time (MLT) by Geotail spacecraft and ∼1900 MLT Cluster spacecraft, which detected rolled‐up MHD‐scale vortices generated Kelvin‐Helmholtz instability (KHI) under prolonged northward interplanetary field conditions. Our purpose is to address excitation process KHI, ion‐scale structures vortices, formation mechanism low‐latitude (LLBL). The observed KH wavelength...