Search Publications
Characteristics of merging at the magnetopause inferred from dayside 557.7-nm all-sky images: IMF drivers of poleward moving auroral forms
Winningham, J. D.; Balogh, A.; Farrugia, C. J. +10 more
We combine in situ measurements from Cluster with high-resolution 557.7 nm all-sky images from South Pole to investigate the spatial and temporal evolution of merging on the dayside magnetopause. Variations of 557.7 nm emissions were observed at a 6 s cadence at South Pole on 29 April 2003 while significant changes in the Interplanetary Magnetic F…
Propagation pattern of low frequency waves in the terrestrial magnetosheath
Glassmeier, K. -H.; Narita, Y.
Propagation pattern (distribution of phase velocities) is determined in three dimensions in the terrestrial magnetosheath on a statistical basis using Cluster spacecraft observations. It is found that the anti-sunward propagation dominates and that the propagation direction is toward the magnetosheath flank at smaller zenith angles, while it is to…
Flux closure during a substorm observed by Cluster, Double Star, IMAGE FUV, SuperDARN, and Greenland magnetometers
Wild, J. A.; Lucek, E. A.; Milan, S. E. +5 more
We examine magnetic flux closure during an extended substorm interval on 29 August 2004 involving a two-stage onset and subsequent re-intensifications. Cluster and Double Star provide observations of magnetotail dynamics, while the corresponding auroral evolution, convection response, and substorm current wedge development are monitored by IMAGE F…
Cluster observations of a structured magnetospheric cusp
Balogh, A.; Fazakerley, A. N.; André, M. +8 more
On 18 April 2002 the Cluster spacecraft crossed through the northern outer magnetospheric cusp region during 16:25-17:55 UT when the solar wind dynamic pressure was rather low (<2 nPa) and IMF Bz was more negative than IMF By. The Cluster data from the FGM, CIS, PEACE, EFW, WHISPER and STAFF instruments reveal that the cus…
VLF/ELF wave activity in the vicinity of the polar cusp: Cluster observations
Zong, Q. -G.; Lucek, E.; Maksimovic, M. +9 more
Observations by the Cluster spacecraft of VLF/ELF wave activity show distinct signatures for different regions in the vicinity of high altitude polar cusps, which are identified by using magnetic field and plasma data along spacecraft trajectories. These waves include: (1) Broad band magnetic noise observed in the polar cusp at frequencies from se…
Alfvénic turbulence in solar wind originating near coronal hole boundaries: heavy-ion effects?
Bavassano, B.; Pietropaolo, E.; Bruno, R. +1 more
The mid-latitude phases of the Ulysses mission offer an excellent opportunity to investigate the solar wind originating near the coronal hole boundaries. Here we report on Alfvénic turbulence features, revealing a relevant presence of in-situ generated fluctuations, observed during the wind rarefaction phase that charaterizes the transition from f…
The association of coronal mass ejections with their effects near the Earth
Schwenn, R.; Gonzalez, W. D.; Huttunen, E. +1 more
To this day, the prediction of space weather effects near the Earth suffers from a fundamental problem: The radial propagation speed of "halo" CMEs (i.e. CMEs pointed along the Sun-Earth-line that are known to be the main drivers of space weather disturbances) towards the Earth cannot be measured directly because of the unfavorable geometry. From …
Properties and geoeffectiveness of magnetic clouds in the rising, maximum and early declining phases of solar cycle 23
Schwenn, R.; Bothmer, V.; Koskinen, H. E. J. +1 more
The magnetic structure and geomagnetic response of 73 magnetic clouds (MC) observed by the WIND and ACE satellites in solar cycle 23 are examined. The results have been compared with the surveys from the previous solar cycles. The preselected candidate MC events were investigated using the minimum variance analysis to determine if they have a flux…
Electric current and magnetic field geometry in flapping magnetotail current sheets
Sauvaud, J. -A.; Balogh, A.; Zhang, T. L. +11 more
Using four-point magnetic field measurements by the Cluster spacecraft, we statistically analyze the magnetic field and electric current configurations during rapid crossings of the current sheet observed in July-October 2001 at geocentric distances of 19 RE. The database includes 78 crossings, specially selected to apply multi-point da…
The Double Star magnetic field investigation: instrument design, performance and highlights of the first year's observations
Balogh, A.; Zhang, T. L.; Glassmeier, K. -H. +19 more
One of the primary objectives of the Double Star mission is the accurate measurement of the magnetic field vector along the orbits of the two spacecraft. The magnetic field is an essential parameter for the understanding of space plasma processes and is also required for the effective interpretation of data from the other instruments on the spacec…