Special Section of JGR Space Physics Marks Polar

1
Special Section of JGR Space Physics Marks
Polars 5th Anniversary
This April special section is first of two Polar
special sections to be published in JGR this year

• Some featured articles
• Mozer et al., Origin geometry of upward
  parallel electric fields
• Frank et al., Encounters of the substorm onset
  region
• Reeves et al., The storm-substorm relationship
• Crumley et al., Studies of ion solitary waves
• Maynard et al., The magnetospheric sash and its
  implications
• Trattner et al., Origins of cusp energetic
  particles
• Fuselier et al., O in the cusp, implications for
  reconnection

September 4, 1996
26 papers of new accomplishments in particle
acceleration, reconnection, substorm onset, ion
outflow, auroral power and precipitation, and
energetic particles of the radiation belts.
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Polar Resurrects TIMAS, Immediately Detects New
Terrestrial Ion Signature
Measurements
On Oct 29, 1999, all telemetry reported from
TIMAS became invalid (zeroes). Thereafter,
collection of valid values was sporadic, ending
on July 15, 2000
The fault appeared to be located at the interface
between TIMAS and the GGS Telemetry Module 1
(GTM1) and was loosely temperature dependent.
On Mar 27, 2001 the Polar spacecraft switched to
its backup telemetry module and restored
telemetry capture of the TIMAS mid-energy mass
spectrometer.
TIMAS immediately detected new terrestrial source
ion signature at the dayside magnetosphere during
magnetic storm period.
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Polar Resurrects TIMAS, Immediately Detects New
Terrestrial Ion Signature
Polars orbit has precessed so that it samples
regions near the dayside equatorial magnetopause
with high-temporal and spatial resolution the
low-latitude boundary layer, turbulent boundary
layer, magnetosphere, and magnetosheath.
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Polar Resurrects TIMAS, Immediately Detects New
Terrestrial Ion Signatures
Observations
TIMAS energy-time spectrogram obtained as Polar
passed through the polar cap, cusp and dayside
magnetosphere.
Obtained shortly after the onset of the large
magnetic storm on 3/31/2001, these data show
intense ionosphere O flowing at high altitudes
well equatorward of the cusp.
The free energy to drive these ions to such high
altitudes on the dayside appears to be related to
large scale electric fields generated during the
storm period.
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Other Polar Particle Detectors Report Similar
Observations
Observations
TIDE low-energy ion data, from a similar orbit,
clearly demonstrate the presence of the
terrestrial source ions within the turbulent
boundary layer. Within this layer, circularly
polarized waves accelerate the plasmaspheric-like
ions to 30-40 km/s perpendicular to B.
6
New Dayside LLBL Observations Define Path for
Circulation of Terrestrial Particles
Interpretation and Implications

• Based on density ratios and low field-aligned
  drifts, the plasma is of plasmaspheric origin.
• Likely to be associated with plasma tails
  observed by IMAGE that show a convection path for
  plasmaspheric ions to the magnetopause.
• Polar flies through the region of emission seen
  by IMAGE

provides composition and absolute density for
observations quantifies source strength
determines plasma processes for the transport
of plasmaspheric ions to the plasma sheet a
source that had been proposed but not directly
observed until IMAGE imaged the path and Polar
observed the entry into the boundary layer.