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


Narayan chapagain jonathan makela john meriwether dan fisher

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.


Narayan chapagain jonathan makela john meriwether dan fisher

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


Comparison of winds and epb velocities1

Comparison of Winds and EPB Velocities

Peru-Chile


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%)


Comparison of winds and plasma drifts

Comparison of Winds and Plasma Drifts

Peru


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%)


Comparison of winds with epb and plasma drifts

Comparison of Winds with EPB and Plasma Drifts

Wind-EPB-Plasma


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.


Thanks

Thanks


Plasma drifts from jicamarca isr measurements

Plasma Drifts from Jicamarca ISR Measurements

Zonal Velocity (m/s)


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