Search Publications
Solar activity variations of the ionospheric peak electron density
Liu, Libo; Wan, Weixing; Ning, Baiqi +2 more
The daily averaged Solar EUV Monitor (SEM)/Solar Heliospheric Observatory (SOHO) EUV measurements, solar proxies, and foF2 data at 20 ionosonde stations in the east Asia/Australia sector are collected to investigate the solar activity dependences of the ionospheric peak electron density (NmF2). The intensities of solar EUV from the SEM/SOHO measur…
Joint observations by Cluster satellites of bursty bulk flows in the magnetotail
Zhang, T. L.; Dandouras, I.; Lucek, E. +9 more
Using the observations of three satellites of Cluster (C1, C3, and C4) during the periods July to October 2001 and July to October 2002, we study 209 active time bursty bulk flows (BBFs), the difference between single satellite observations and multisatellite observations, and the difference among three selection criteria (two about BBFs and one a…
Coronal prominence structure and dynamics: A magnetic flux rope interpretation
Gibson, S. E.; Fan, Y.
The solar prominence is an example of a space physics phenomenon that can be modeled as a twisted magnetic flux tube or magnetic flux "rope." In such models the prominence is one observable part of a larger magnetic structure capable of storing magnetic energy to drive eruptions. We show how a flux rope model explains a range of observations of pr…
Single-spacecraft detection of rolled-up Kelvin-Helmholtz vortices at the flank magnetopause
RèMe, H.; Hasegawa, H.; Fujimoto, M. +3 more
Recent numerical simulations suggest that as soon as the Kelvin-Helmholtz instability (KHI) has grown nonlinearly to form a highly rolled-up vortex, plasma mixing is inevitably achieved within the vortex. Identification of rolled-up vortices by in situ measurements is therefore an important task as a step to establish the mechanism by which solar …
Kinetic simulations of ring current evolution during the Geospace Environment Modeling challenge events
Thomsen, M. F.; Mouikis, C. G.; Jordanova, V. K. +5 more
We investigate the temporal and spatial evolution of the ring current during two storms selected for study by the Geospace Environment Modeling (GEM) program using our kinetic drift-loss model coupled with a time-dependent plasmasphere model. We use geosynchronous data from LANL satellites to model the inflow of plasma from the magnetotail. We com…
Constraints on the global structure of magnetic clouds: Transverse size and curvature
Liu, Y.; Wang, C.; Richardson, J. D. +3 more
We present direct evidence that magnetic clouds (MCs) have highly flattened and curved cross section resulting from their interaction with the ambient solar wind. Lower limits on the transverse size are obtained for three MCs observed by ACE and Ulysses from the latitudinal separation between the two spacecraft, ranging from 40° to 70°. The cross-…
Coronal mass ejections and magnetic flux buildup in the heliosphere
Owens, M. J.; Crooker, N. U.
To test for magnetic flux buildup in the heliosphere from coronal mass ejections (CMEs), we simulate heliospheric flux as a constant background open flux with a time-varying interplanetary CME (ICME) contribution. As flux carried by ejecta can only contribute to the heliospheric flux budget while it remains closed, the ICME flux opening rate is an…
Dynamics of thin current sheets associated with magnetotail reconnection
Balogh, A.; RèMe, H.; Fazakerley, A. N. +7 more
We have examined the detailed structure of thin current sheets and their evolution during a substorm interval on 24 August 2003, when Cluster experienced several rapid current sheet crossings within a couple of ion gyrotimes. These crossings took place during an interval of high-speed ion flows with BZ reversals and signatures of accele…
Alfvén vortex filaments observed in magnetosheath downstream of a quasi-perpendicular bow shock
André, M.; Maksimovic, M.; Alexandrova, O. +3 more
Magnetic field fluctuations in the frequency range [0.02-12.5] Hz are studied with the four Cluster satellites in the Earth magnetosheath downstream of a quasi-perpendicular bow shock. The turbulent spectrum presents a spectral break accompanied by a broad maximum usually interpreted as due to Alfvén ion cyclotron waves. In this paper we establish…
Propagation of whistler mode chorus to low altitudes: Spacecraft observations of structured ELF hiss
Gurnett, D. A.; Pickett, J. S.; Parrot, M. +3 more
We interpret observations of low-altitude electromagnetic ELF hiss observed on the dayside at subauroral latitudes. A divergent propagation pattern has been reported between 50° and 75° of geomagnetic latitude. The waves propagate with downward directed wave vectors which are slightly equatorward inclined at lower magnetic latitudes and slightly p…