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Electrodynamics of Low-latitude Thermosphere-Ionosphere from Coincident Measurements of Zonal Neutral Winds, EPB and Plasma Drift Velocities. Narayan Chapagain, Jonathan Makela John Meriwether, Dan Fisher Jorge Chau , Ricardo Buriti.

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narayan chapagain jonathan makela john meriwether dan fisher jorge chau ricardo buriti

Electrodynamics of Low-latitude Thermosphere-Ionosphere from Coincident Measurements of Zonal Neutral Winds, EPB and Plasma Drift Velocities

Narayan Chapagain, Jonathan Makela

John Meriwether, Dan Fisher

Jorge Chau, Ricardo Buriti

AOGS 10th Annual Meeting, 24-28 June 2013

outlines
Outlines
  • Measurement Techniques
  • Comparison of zonal neutral winds with:
  • EPB velocities from Brazil
  • Plasma drifts (Peru) and EPB velocity (Chile)
  • Summary
instrumentation sites
Instrumentation Sites
  • Jicamarca ISR: Plasma drifts
  • Fabry-Perot Interferometers (FPIs): Neutral winds
  • Optical imaging systems: EPB velocity

Peru

Caj

Cariri

Jicamarca

Brazil

Merihill

Nazca

Chile

slide4

Measurement Techniques: Neutral Winds

Brazil

  • Two techniques:
  • Cardinal mode (N-E-S-W): Data from Caj only.
  • Common volume mode (CVN-IN-CVS): Data from both Caj and Cariri.
  • Measurements of Doppler shifts of redline emission at 250 km.
slide5

EPB Drift Velocity

Brazil

  • Images projected onto geographic coordinates at altitude of 250 km
  • Intensity cut through the image along a line of constant magnetic latitude
    • Chosen to correspond to the magnetic latitude of the FPI pierce point used in the comparison
  • Data stacked in time to get keogram plot to estimate velocity

W

E

database brazil
Database: Brazil
  • Kp<3
  • 65<F10.7<80
comparison of winds and epb velocities
Comparison of Winds and EPB Velocities

Brazil

Chapagainet al. (2012), JGR

differences in winds and epb velocities
Differences in Winds and EPB Velocities
  • Wind≅EPB (40-95%)
  • Excellent agreement after ~23:00 LT
  • F-region dynamo fully developed.

Brazil

(57 nights)

  • Wind>EPB (2-60%)
  • Early evening discrepancy
  • F-region dynamo not fully activated.
  • Wind<EPB (22:00-00:00 LT)
peru chile
Peru-Chile
  • A bi-static FPI network in Peru (Merihill and Nazca)
  • Plasma Drifts from ISR from Jicamarca Radio Observatory (JRO)
  • Narrow Field Optical Imaging system (PICASSO) from CTIO Chile
database peru and chile
Database: Peru and Chile
  • Kp<3
  • 80<F10.7<140
differences in winds and epb velocities1
Differences in Winds and EPB Velocities

(43 nights)

Peru-Chile

  • Wind≅EPB (55-65%)
  • Wind<EPB (10-25%)
  • EPB velocity corresponds to at higher apex altitude (~400 km)
  • Wind>EPB (5-20%)
differences in winds and plasma drifts
Differences in Winds and Plasma Drifts

(18 nights)

Peru

  • Wind≅Drifts (~60-80%)
  • Wind<Drifts (~10-15%)
  • Wind>Drifts (~5-35%)
summary
Summary
  • Brazil results in the early evening hour most often (~60%) show the bubble velocity being slower than the neutral winds that reveal the F-region dynamo is not fully activated.
  • Around midnight and post midnight hours, there is excellent agreement between zonal neutral winds and EPB velocities illustrating that F-region dynamo fully developed and the EPB velocity indicates as a background motion.
  • The neutral winds and plasma drifts from Peru show similar temporal variability with EPB velocity from Chile, however, the difference in their magnitude possibly due to EPB velocity estimated corresponding to an apex altitude of ~400 km.
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