Search Publications
Type II solar radio bursts: 2. Detailed comparison of theory with observations
Cairns, Iver H.; Robinson, P. A.; Hillan, D. S.
In this paper, the second in a two paper series, we quantitatively compare a detailed theory for type II solar radio bursts with observations and extract the parameters of the associated shocks. We use the techniques and assessment parameters developed and demonstrated in the companion paper for artificial data sets and solar wind models. Here we …
Is there long-range memory in solar activity on timescales shorter than the sunspot period?
Rypdal, M.; Rypdal, K.
The sunspot number (SSN), the total solar irradiance (TSI), a TSI reconstruction, and the solar flare index (SFI) are analyzed for long-range persistence (LRP). Standard Hurst analysis yields H ≈ 0.9, which suggests strong LRP. However, solar activity time series are nonstationary because of the almost-periodic 11 year smooth component, and the an…
Cluster multipoint study of the acceleration potential pattern and electrodynamics of an auroral surge and its associated horn arc
Lucek, E.; Nilsson, H.; Karlsson, T. +10 more
Cluster results are presented from the acceleration region of an auroral surge and connected horn arc, observed during an extended time period of substorm activity. The Cluster spacecraft crossed different magnetic local time (MLT) sectors of the surge and horn, with lag times of 2-10 min. Acceleration potential patterns are derived for the horn a…
The wide skirt of the bashful ballerina: Hemispheric asymmetry of the heliospheric magnetic field in the inner and outer heliosphere
Mursula, K.; Virtanen, I. I.
We reanalyze the observations of the heliospheric magnetic field (HMF) made by the Pioneer 10 and 11 and Voyager 1 and 2 heliospheric probes since 1972, and calculate the HMF sector occurrence ratios and tangential component strengths in the different regions of the heliosphere. Observations at the distant probes and at 1 AU show a very consistent…
Storm and substorm effects on magnetotail current sheet motion
Lester, M.; Milan, S. E.; Fear, R. C. +1 more
Passes through the mid-region of the magnetotail by the Cluster spacecraft from 2001 to 2007 have been examined to study the dynamics of the cross-tail current sheet. Cluster is ideally placed to study this region due to the orientation of the orbit in the magnetotail, such that the current sheet is sampled at distances downtail from about 8-19 R<…
Cluster observations of the dusk flank magnetopause near the sash: Ion dynamics and flow-through reconnection
Dunlop, Malcolm; Farrugia, Charles J.; Rème, Henri +5 more
Compared to the dayside, dynamics on the flanks of the magnetopause are poorly understood. To help bridge this knowledge gap we analyzed Cluster plasma and field measurements acquired during a 90-min period on 20 November 2003 when Cluster crossed the magnetopause four times in the vicinity of the sash. MHD simulations provide a context for Cluste…
Modeling of electron fluxes in the Enceladus plume
Coates, A. J.; Jones, G. H.; Cravens, T. E. +2 more
Observations by instruments onboard the Cassini spacecraft of Saturn's icy satellite Enceladus have shown that a plume containing water vapor and ice grains is present in the southern hemisphere. Energy distributions of electrons in this plume were measured by the electron sensor part of the Cassini plasma spectrometer (CAPS - ELS). A significant …
The detection of energetic electrons with the Cassini Langmuir probe at Saturn
Schippers, P.; Gurnett, D. A.; Krupp, N. +10 more
The Cassini Langmuir probe, part of the Radio and Plasma Wave Science (RPWS) instrument, has provided a wealth of information about the cold and dense plasma in the Saturnian system. The analysis of the ion side current (current for negative potentials) measured by the probe from 2005 to 2008 reveals also a strong sensitivity to energetic electron…
Study of kinetic Alfvén wave and whistler wave spectra and their implication in solar wind plasma
Sharma, R. P.; Dwivedi, Navin Kumar; Batra, Karuna
This work presents the numerical simulation of the nonlinear evolution of kinetic Alfvén wave (KAW), in a parametric regime consistent with the solar wind plasmas. The nonlinear dynamical equation of KAW satisfies the modified nonlinear Schrödinger equation when incident pump KAW has a small perturbation. Numerical simulation has been done to solv…
Simultaneous ground-satellite observations of meso-scale auroral arc undulations
Lester, M.; Milan, S. E.; Sato, N. +4 more
We present simultaneous ground-based and in situ measurements of a train of meso-scale (about 100-300 km) auroral arc undulations, occurring in the postmidnight sector (∼1 MLT) between 0040 UT and 0054 UT on September 21, 2009. The undulations appeared at the auroral poleward boundary, and then moved eastward with a speed of 0.9-2.2 km s-1