Search Publications
Statistical analysis of earthward flow bursts in the inner plasma sheet during substorms
Zhang, T. L.; Dandouras, I.; Lucek, E. +5 more
In this article, we study the velocity distribution, density, duration, and energy transport of earthward flow bursts in the inner plasma sheet (IPS) during three substorm phases using the data of Cluster in 2001 and 2002. The mean peak velocity of earthward flow bursts in recovery phases (390 km/s) is smaller than those in growth and expansion ph…
Transient auroral features at Saturn: Signatures of energetic particle injections in the magnetosphere
Krupp, N.; Roussos, E.; Mitchell, D. G. +7 more
We report for the first time transient isolated auroral spots at Saturn's southern polar region, based on Hubble Space Telescope (HST) FUV images. The spots last several minutes and appear distinct from the rest of the auroral emissions. We study two sets of HST and Cassini observations during which Cassini instrumentation detected signatures of e…
Operational validation of HAFv2's predictions of interplanetary shock arrivals at Earth: Declining phase of Solar Cycle 23
Dryer, M.; Fry, C. D.; McKenna-Lawlor, S. M. P. +3 more
This is the third in a series of papers showing the performance of the Hakamada-Akasofu-Fry version 2 (HAFv2) model in predicting, in the operational environment, the arrival of interplanetary shocks at Earth. The first and second studies covered the time of the rise and maximum of Solar Cycle 23. This study covers the declining phase, through Dec…
Hot flow anomalies at Saturn's bow shock
Coates, A. J.; Dougherty, M. K.; Thomsen, M. F. +8 more
We present evidence for the occurrence of hot flow anomalies (HFAs) at Saturn's bow shock. A survey of Cassini magnetic field and electron data taken upstream of the dawn flank bow shock is carried out in order to identify Kronian HFAs. Seventeen events are identified that were all associated with energization of the solar wind electrons and satis…
Phase relation of oscillations near the planetary period of Saturn's auroral oval and the equatorial magnetospheric magnetic field
Nichols, J. D.; Cowley, S. W. H.; Provan, G.
Previous analyses of Hubble Space Telescope (HST) images of Saturn's southern auroras obtained during two campaigns, in January 2007 and February 2008, have revealed that the auroral oval oscillates at a period close to the planetary rotation period, with its center describing an elongated ellipse of semimajor axis ∼2° colatitude aligned along the…
Magnetic turbulence in space plasmas: Scale-dependent effects of anisotropy
Perri, S.; André, M.; Bruno, R. +4 more
The presence of a background magnetic field induces anisotropy in magnetic turbulence. Understanding properties of anisotropy is important to characterize turbulence power spectrum. This paper presents a case study of anisotropy by using a minimum variance analysis, in three different regions of the heliosphere, namely in the solar wind, and in th…
Size, shape, and orientation of magnetosheath mirror mode structures
Horbury, T. S.; Lucek, E. A.
Information about the size, shape, and orientation of mirror mode structures in the magnetosheath is obtained by combining data from the four Cluster spacecraft, resulting in an estimate of the form of the magnetic field magnitude spatial autocorrelation function. It is shown that the longest direction of the structures is typically inclined at ar…
Poleward arcs of the auroral oval during substorms and the inner edge of the plasma sheet
Haerendel, Gerhard
An analytical model for the connection between the near-Earth edge of the plasma sheet at substorm onset and the auroral arcs at the poleward edge of the auroral oval is presented. The connection is established through the existence of a Boström type I current system. Its generator is assumed to be constituted by a narrow high-beta plasma layer lo…
Substorm expansion triggered by a sudden impulse front propagating from the dayside magnetopause
Dandouras, I.; Nakamura, R.; Lucek, E. A. +12 more
We examine a substorm expansion on 21 June 2007, which occurred <2 min after a solar wind discontinuity accompanied by a dynamic pressure (P d ) increase impinged on the magnetopause. To investigate how the perturbation due to such P d increase propagates in the magnetosphere and what the timing analysis may imply about…
Conjugate ionospheric equivalent currents during bursty bulk flows
Nakamura, R.; Kauristie, K.; Amm, O. +1 more
Ionospheric equivalent currents related to bursty bulk flows (BBF) during Cluster and the International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer network conjunctions between 2001 and 2006 are studied. A geomagnetically southeast-northwest aligned, relatively narrow channel of northwestward equivalent current density with downwa…