MSSL Space Plasma Science Nuggets
High-time-resolution observations of an FTE using Cluster
Publication date: 29 September 2014
We have presented the Cluster observations of a crater FTE on 12 February 2007, when the quartet was located in the low-latitude boundary layer, and widely separated on the magnetopause plane. The passage of the structure was sequentially observed by Cluster 2, 3, 4 and 1 respectively, analysed in detail. But what are flux transfer events, and why are they important within the magnetosphere?
New and improved analytic expressions for ULF wave radiation belt radial diffusion coefﬁcients
Publication date: 31 March 2014
Ozeke et al.  presented analytic expressions for ULF wave-derived radiation belt radial diffusion coefﬁcients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefﬁcients are derived from statistical representations of ULF wave power, electric ﬁeld power mapped from ground magnetometer data, and compressional magnetic ﬁeld power from in situ measurements.
Detailed azimuthal structure of the substorm current wedge
Publication date: 12 February 2014
During the most dynamic auroral displays, known as substorm, electrical current is diverted from the magnetosphere through the ionosphere. The passage of this current through the upper atmosphere causes the gas to glow giving us the aurora. Since the 1970s it has been thought that this diverted current forms a "substorm current wedge" with upwards current on the duskward side and downward current on the dawnward side.
Automated determination of auroral breakup during the substorm expansion phase using all-sky imager data
Publication date: 1 February 2014
The detailed spatial structure of ﬁeld-aligned currents comprising the substorm current wedge
Publication date: 1 December 2013
We present a comprehensive two-dimensional view of the ﬁeld-aligned currents (FACs) during the late growth and expansion phases for three isolated substorms utilizing in situ observations from the Active Magnetosphere and Planetary Electrodynamics Response Experiment and from ground-based magnetometer and optical instrumentation from the Canadian Array for Realtime Investigations of Magnetic Activity and Time History of Events and Macroscale Interactions during Substorms ground-based arrays.
Discovery of the action of a geophysical synchrotron in the Earth’s Van Allen radiation belts
Publication date: 1 November 2013
Although the Earth's Van Allen radiation belts were discovered over 50 years ago, the dominant processes responsible for relativistic electron acceleration, transport and loss remain poorly understood. Here we show evidence for the action of coherent acceleration due to resonance with ultra-low frequency waves on a planetary scale.
The influence of magnetospheric convection and magnetopause motion on Radiation Belt electrons
Publication date: 30 June 2013
Understanding the acceleration, transport and loss of relativistic electrons in Earth’s magnetosphere is a high-priority international science objective. Observations indicate that there are a vast number of effects to be considered in this region ranging from large-scale global effects to effects on the electron gyroscale and from the interaction of electrons with electromagnetic wave processes, to global changes in the Earth’s magnetosphere.
Poleward Boundary Intensifications and Bursty Bulk Flows do not coherently drive the substorm current wedge
Publication date: 1 June 2013
Rae et al.  published a comment on a recent Nishimura et al.  paper that hypothesized that individual flow bursts created the field-aligned currents (FACs) that form the substorm current wedge (SCW). In their comment, Rae et al.  systematically broke down the underpinning assumptions of the Nishimura paper.
Structure and variability of the auroral acceleration region
Publication date: 5 February 2013
Bright auroral arc appear when charged particles from the magnetosphere are accelerated into the upper atmosphere. Collisions between charged particles and neutrals excite the electrons in the neutral particles which then de-excite by emitting auroral light. Particles, in particular electrons, are accelerated out of the magnetosphere and into the atmosphere by magnetic-field-aligned electric potential drops in a region known as the auroral acceleration region (AAR). In a recent paper, Forsyth et al.  investigated the temporal variability and spatial structure in one such region.
What is the source of magnetotail flux-ropes?
Publication date: 12 December 2011
Travelling compression regions (TCRs) are perturbations in the magnetotail lobe magnetic field caused by structures moving Earthward or tailward within the plasma sheet. Previous works have suggested that these structures are created by either time-dependant reconnection occurring at a single X-line, forming a flux-bulge-type structure, or space-variant reconnection at multiple X-lines, forming flux-rope-type structures. By analysing a TCR and its source structure using the Cluster spacecraft, Beyene et al. (2011) have endeavoured to determine which of these mechanisms creates TCRs.