Search Publications
Influence of coronal mass ejection interaction on propagation of interplanetary shocks
Howard, R. A.; Gopalswamy, N.; Michalek, G. +3 more
We studied 91 interplanetary (IP) shocks associated with coronal mass ejections (CMEs) originating within about ±30° in longitude and latitude from the center of the Sun during 1997-2002. These CMEs cover a wide range of initial speeds of about 120 to 2400 kms-1 and they also include a special population of 25 interacting CMEs. This stu…
Iron charge state distributions as an indicator of hot ICMEs: Possible sources and temporal and spatial variations during solar maximum
Lepri, S. T.; Zurbuchen, T. H.
It has been shown that Fe charge states greater than and equal to 16 are often observed in the presence of interplanetary coronal mass ejections (ICMEs) at 1 AU. These elevated charge states, representative of hot source regions on the Sun, provide an identifier of ICMEs independent of expansion processes and heliocentric distance. Using this new …
Jupiter's low-frequency radio spectrum from Cassini/Radio and Plasma Wave Science (RPWS) absolute flux density measurements
Kurth, W. S.; Cecconi, B.; Zarka, P.
We apply the calibration method developed by [2001] to the data from the Cassini/Radio and Plasma Wave Science (RPWS) High-Frequency Receiver in order to derive flux density measurements of six components of the Jovian low-frequency radio spectrum over the full frequency range of the instrument (3.5 kHz to 16.1 MHz). The estimated accuracy is bett…
Characteristics of Saturn's FUV aurora observed with the Space Telescope Imaging Spectrograph
Trauger, John T.; Gustin, Jacques; Clarke, John T. +3 more
We analyze a set of 15 FUV images obtained between October 1997 and January 2001 with the Hubble Space Telescope Imaging Spectrograph (STIS), providing a good view of Saturn's south auroral oval. It is found that the morphology and brightness distribution of the aurora are dynamical with variations occurring on time scales of hours or less. The da…
Magnetic turbulence in the plasma sheet
Balogh, A.; Zhang, T. L.; Klecker, B. +9 more
Small-scale magnetic turbulence observed by the Cluster spacecraft in the plasma sheet is investigated by means of a wavelet estimator suitable for detecting distinct scaling characteristics even in noisy measurements. The spectral estimators used for this purpose are affected by a frequency-dependent bias. The variances of the wavelet coefficient…
Cluster observations of hot flow anomalies
Balogh, A.; Dandouras, I.; RèMe, H. +2 more
On 2 April 2002, Cluster entered the solar wind at high northern latitudes and observed a series of disturbances upstream of the bow shock. We suggest that these were signatures of a sequence of hot flow anomalies (HFAs), observed at different stages of development. We estimate the orientation and motion of the HFAs and structures within them usin…
Helicity of magnetic clouds and their associated active regions
Pevtsov, Alexei A.; Leamon, Robert J.; Canfield, Richard C. +3 more
In this work we relate the magnetic and topological parameters of twelve interplanetary magnetic clouds to associated solar active regions. We use a cylindrically symmetric constant-α force-free model to derive field line twist, total current, and total magnetic flux from in situ observations of magnetic clouds. We compare these properties with th…
Inferring of flux rope orientation with the minimum variance analysis technique
Fu, S. Y.; Pu, Z. Y.; Zong, Q. G. +3 more
The accuracy in flux rope orientation inference from both the traditional magnetic-field-based minimum variance analysis (BMVA) technique and the current-based MVA (CMVA) approach is examined. Four different flux rope models are used in the MVA test. It is found that the directions of eigenvectors of MVA are critically dependent on the spacecraft …
Differential velocity between solar wind protons and alpha particles in pressure balance structures
Sakurai, Takashi; Suess, Steven T.; Steinberg, John T. +1 more
Pressure balance structures (PBSs) are a common high-plasma beta feature in high-latitude, high-speed solar wind. They have been proposed as remnants of coronal plumes. If true, they should reflect the observation that plumes are rooted in unipolar magnetic flux concentrations in the photosphere and are heated as oppositely directed flux is advect…
Energy-flux relationship in the FUV Jovian aurora deduced from HST-STIS spectral observations
Clarke, J. T.; Cowley, S. W. H.; Grodent, D. +3 more
Far ultraviolet spectral observations of the Jovian aurora have been made since 1997 with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope at low spectral resolution. The combination of the spectral resolution with the intensity variation along the STIS slit provides information on the latitudinal variation of th…