Studies of Ionospheric Plasma Structuring at Low Latitudes from Space and Ground, their Modeling and Relationship to Scintillations Sunanda Basu Center for Space Physics, Boston University

1
Studies of Ionospheric Plasma Structuring at Low
Latitudes from Space and Ground, their Modeling
and Relationship to ScintillationsSunanda
BasuCenter for Space Physics,Boston University

• GUVI has provided a tool for global mapping of
  the equatorial anomaly as shown in Figures 1 and
  2
• GUVI images at dusk demonstrate the great
  variability of the anomaly over narrow swaths of
  longitude even on magnetically quiet days
• Combining GUVI images with scintillation and
  satellite in-situ data have provided insights
  into day-to-day variability of equatorial
  irregularity generation
• Attempts are being made to reproduce the observed
  longitudinal variability by introducing
  longitudinally dependent instability drivers in
  the SAMI 3 model
• The ultimate goal is to determine the underlying
  electrodynamics that cause such longitudinally
  varying equatorial anomaly structure at dusk.

2
Dayto-Day Variability 0f Equatorial
Scintillation TIMED/GUVI and DMSP
Day-to Day Variability of Equatorial
Scintillation TIMED/GUVI and DMSP

• Anomaly crest separation asymmetry related to
  E-field neutral wind
• Electric field strength controls vertical drift
  correlated with instability onset and subsequent
  irregularity generation
• Large meridional separation corresponds to
  favorable conditions for scintillation
• Intense L-band scint. seen at Calcutta under
  anomaly crest
• Coordinated DMSP data show bubbles at 840 km

3
Day-to-day Variability of Equatorial
Scintillation TIMED/GUVI and DMSP

• Collapse of anomaly in
• Indian sector on day 33 is correlated with
  absence of VHF scintillations at both Calcutta
  and Singapore
• Coordinated DMSP data show lack of bubbles and
  single density peak over magnetic equator
• Initial attempt made to model the longitudinal
  confinement of collapse region by SAMI 3