Search Publications
The redshifted footpoints of coronal loops
Parenti, S.; Dwivedi, B. N.; Curdt, W. +1 more
The physics of coronal loops holds the key to understanding coronal heating and the flow of mass and energy in the region. However, the energy source, structure maintenance and mass balance in coronal loops are not yet fully understood. Observations of blue- and redshifted emissions have repeatedly been used in the construction of loop models. But…
Least-squares multi-spacecraft gradient calculation with automatic error estimation
de Keyser, J.
Multi-spacecraft missions allow the gradient of important physical quantities in the terrestrial environment to be determined. The gradient can be computed from four simultaneous measurements in a straightforward way, but this computation does not produce proper error estimates, making it hard to assess the meaningfulness of the result. Recently d…
GALS - Gradient Analysis by Least Squares
Hamrin, M.; Vaivads, A.; Rönnmark, K. +2 more
We present a method, GALS (Gradient Analysis by Least Squares) for estimating the gradient of a physical field from multi-spacecraft observations. To obtain the best possible spatial resolution, the gradient is estimated in the frame of reference where structures in the field are essentially locally stationary. The estimates are refined iterativel…
Foreshock density holes in the context of known upstream plasma structures
Parks, G. K.; Mazelle, C.; Harris, A. +4 more
We present case examples of foreshock density holes and results from a statistical survey, which provide additional characterizations of these recently-described structures. Specific effort is made to place these objects into context with well-studied foreshock phenomena, such as hot flow anomalies (HFAs) and large-amplitude magnetic pulsations (S…
Correlation length of magnetosheath fluctuations: Cluster statistics
Němeček, Z.; Gutynska, O.; Afránková, J. Å.
Magnetosheath parameters are usually described by gasdynamic or magnetohydrodynamic (MHD) models but these models cannot account for one of the most important sources of magnetosheath fluctuations the foreshock. Earlier statistical processing of a large amount of magnetosheath observations has shown that the magnetosheath magnetic field and plasma…
Off-limb EUV observations of the solar corona and transients with the CORONAS-F/SPIRIT telescope-coronagraph
Slemzin, V.; Kuzin, S.; Zhitnik, I. +4 more
The SPIRIT telescope aboard the CORONAS-F satellite (in orbit from 26 July 2001 to 5 December 2005), observed the off-limb solar corona in the 175 Å (Fe IX, X and XI lines) and 304 Å (He II and Si XI lines) bands. In the coronagraphic mode the mirror was tilted to image the corona at the distance of 1.1...5 Rsun from the solar center, t…
The wave surveyor technique for fast plasma wave detection in multi-spacecraft data
Narita, Y.; Constantinescu, O. D.; Vogt, J.
Multi-satellite missions like Cluster allow to study the full spatio-temporal variability of plasma processes in near-Earth space, and both the frequency and the wave vector dependence of dispersion relations can be reconstructed. Existing wave analysis methods include high-resolution beamformers like the wave telescope or k-filtering technique, a…
Transients in oxygen outflow above the polar cap as observed by the Cluster spacecraft
Lundin, R.; Yamauchi, M.; Sauvaud, J. -A. +11 more
Oxygen ion outflow associated with the cusp and cleft give rise to persistent oxygen ion beams which can be observed over the polar cap. For high altitude spacecraft such as Cluster these beams are often observed for several hours on each occasion. This allows for a study of typical temporal structures on the time scale of minutes. We have used 3 …
Influence of non-stationary electromagnetic field conditions on ion pick-up at Titan: 3-D multispecies hybrid simulations
Glassmeier, K. -H.; Motschmann, U.; Simon, S.
Titan's interaction with the corotating Saturnian magnetospheric plasma is studied in terms of a three-dimensional electromagnetic hybrid model. This approach treats the electrons as a massless, charge-neutralizing fluid, whereas the ions are represented by macroparticles. The model considers two magnetospheric and three ionospheric ion species. I…
Evidence for particle acceleration in the magnetospheric cusp
Chen, J.
New evidence reveals that the charged particles can be energized locally in the magnetospheric cusp. The power spectral density of the cusp magnetic fluctuations shows increases by up to four orders of magnitude in comparison to an adjacent region. Large fluctuations of the cusp electric fields have been observed with an amplitude of up to 350 mV/…