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The three-dimensional solar wind around solar maximum
McComas, D. J.; Goldstein, B. E.; Schwadron, N. A. +3 more
Ulysses is now completing its second solar polar orbit, dropping back down in latitude as the Sun passes through its post-maximum phase of the solar cycle. A mid-sized circumpolar coronal hole that formed around solar maximum in the northern hemisphere has persisted and produced a highly inclined CIR, which was observed from ~70°N down to ~30°N. W…
Current sheet structure near magnetic X-line observed by Cluster
Balogh, A.; Zhang, T. L.; Klecker, B. +9 more
During the interval 0947-0951 UT on 1 October 2001, when Cluster was located at X GSM = -16.4 R E near Z GSM = 0 in the pre-midnight magnetotail, the Cluster barycenter crosses the neutral sheet four times. High speed proton flow, with reversal from tailward to Earthward, was detected during the crossings. Us…
Current sheet flapping motion and structure observed by Cluster
Balogh, A.; Zhang, T. L.; André, M. +8 more
Fast vertical flapping oscillations of the plasma sheet have been observed by Cluster on September 26, 2001. The flapping motion had vertical speeds exceeding 100 km/s, an amplitude in excess of 1 RE and a quasiperiod of ~3 min. The current sheet was mostly tilted in the Y-Z plane (with the tilt sometimes exceeding 45°). The waves had t…
Cluster observation of a bifurcated current sheet
Balogh, A.; Zhang, T. L.; Nakamura, R. +4 more
The current sheet structure and motion at XGSM = -19.5 RE, observed by Cluster/FGM during 1055-1107 UT on 29 August 2001, is examined. It is found that during the interval 1055-1102 UT the current sheet moves vertically up and down with a velocity of about 60 km/s. During this interval the current sheet has a bifurcated struc…
Simultaneous Cluster and IMAGE observations of cusp reconnection and auroral proton spot for northward IMF
Lundin, R.; Sauvaud, J. -A.; Balogh, A. +22 more
On March 18, 2002, under northward interplanetary magnetic field (IMF) and high (~15 nPa) solar wind dynamic pressure conditions, Cluster observed reconnection signatures and the passage of an X-line at the large (~175°) magnetic-shear high-latitude magnetopause (MP). The observations are consistent with the occurrence of a reconnection site tailw…
Transverse dimensions of chorus in the source region
Gurnett, D. A.; Santolík, O.
We report measurement of whistler-mode chorus by the four Cluster spacecraft at close separations. We focus our analysis on the generation region close to the magnetic equatorial plane at a radial distance of 4.4 Earth's radii. We use both linear and rank correlation analysis to define perpendicular dimensions of the sources of chorus elements bel…
Large solar energetic particle events of cycle 23: A global view
Thompson, B. J.; Kaiser, M. L.; Howard, R. A. +4 more
We report on a study of all the large solar energetic particle (SEP) events that occurred during the minimum to maximum interval of solar cycle 23. The main results are: 1. The occurrence rate of the SEP events, long-wavelength type II bursts and the fast and wide frontside western hemispheric CMEs is quite similar, consistent with the scenario th…
Cluster electric current density measurements within a magnetic flux rope in the plasma sheet
Balogh, A.; Owen, C. J.; Reme, H. +11 more
On August 22, 2001 all 4 Cluster spacecraft nearly simultaneously penetrated a magnetic flux rope in the tail. The flux rope encounter took place in the central plasma sheet, βi ~ 1-2, near the leading edge of a bursty bulk flow. The ``time-of-flight'' of the flux rope across the 4 spacecraft yielded Vx ~ 700 km/s and a diame…
Properties of high heliolatitude solar energetic particle events and constraints on models of acceleration and propagation
Balogh, A.; Krucker, S.; Dalla, S. +10 more
We analyse 9 large solar energetic particle (SEP) events detected by the Ulysses spacecraft at high heliolatitudes during the recent solar maximum polar passes. Properties of time intensity profiles from the Ulysses/COSPIN instrument are compared with those measured by SOHO/COSTEP and Wind/3DP near Earth. We find that onset times and times to maxi…
Bashful ballerina: Southward shifted heliospheric current sheet
Mursula, K.; Hiltula, T.
It is known since long [Rosenberg and Coleman, 1969] that one of the two sectors of the interplanetary magnetic field (IMF) observed at the Earth's orbit dominates at high heliographic latitudes during solar minimum times, reflecting the poloidal structure of the global solar magnetic field at these times. Here we find that while this latitudinal …