Scientific Objectives of Coordinated Ground-Based
Observations With ESA's CLUSTER mission

• Tail phenomena and substorms
  • Location of substorm onset
  • Location of near-Earth neutral line (NENL)
  • Onset time of substorm-enhanced tail reconnection
  • Mechanisms for cross-tail current disruption (CD)
  • Development of CD and evolution into NENL
  • Energy release from tail lobe
  • Pseudo-breakups
  • Structure, evolution and pinch-off time of plasmoids
  • Southward-drifting arcs
  • Nightside ionospheric outflows and tail composition
  • Omega bands
  • Plasma sheet (PS) thinning
  • Field aligned currents and precipitation as a function of substorm phase
  • Westward travelling surge
  • Connection of dayside and nightside auroral intensifications
  • Asymmetric ring current
  • Energetic particle injection
  • Substorm growth phase
  • Polar cap expansion and contraction
  • Convection during substorms
  • IMF and SW triggers of substorms
  • Recovery phase
  • Activations along a contracted auroral oval

• General magnetospheric topology, morphology and dynamics
  • Mapping electric and magnetic fields
  • Double auroral oval and open/closed boundary
  • Lobe field topology (bifurcation and asymmetries)
  • Conjugacy and interhemispheric symmetries and asymmetries
  • Time-dependency of RC drift shells and splitting
  • Detached plasmasphere regions and ionospheric plasma in the dayside magnetosphere
  • Transpolar and other polar cap arcs
  • Auroral acceleration
  • IMF control of convection
  • NBz convection

• Magnetopause and boundary-layers
  • Effects of magnetopause reconnection
  • Location of dayside X-line
  • Conditions at dayside X-line
  • Causes of magnetopause reconnection rate variations
  • Ion transmission factors across magnetopause
  • Cusp ions steps and temporal and spatial variations
  • Maintenance of cusp quasi-neutrality
  • Open and closed low-latitude boundary layers (LLBL)
  • Origin, propagation and lifetime of travelling convection vortices (TCVs)
  • Field-aligned currents and precipitation in TCVs
  • Voltage and thickness of LLBL
  • Local time extent of dayside transients
  • Origin of cleft ion fountain and effects on lobe and PS composition
  • Voltage contribution of reconnection pulses
  • Magnetopause oscillations and surface waves
  • Mid-afternoon auroral bright spot
  • IMF control of dayside ionospheric transients, TCVs and magnetopause flux transfer events (FTEs)
  • SW pressure pulses as a cause of TCVs, magnetopause FTEs and reconnection pulses
  • Spatial distribution and origins of dayside field aligned current
  • Ion acceleration at the magnetopause
  • Motion of newly-reconnected field lines
  • Origin of polar cap patches
  • Origin of dayside ionospheric transients
  • Ionospheric signatures of magnetopause FTEs