characteristics of equatorial plasma bubbles observed by ...diego barros | april/2017 plasma bubles...

Characteristics of equatorial plasma

bubbles observed by TEC map over

South America

Barros, D.; Takahashi, H.; Wrasse, C. M.; Figueiredo, C. A.

Instituto Nacional de Pesquisas EspaciaisSao Jose dos Campos, Sao Paulo, Brazil

April/2017

Diego Barros — April/2017 plasma bubles observed by tec map 1

Outline

1. IntroductionWhat are plasma bubbles?

2. Instrumentation and MetodologyTECdTEC

3. ResultsCharacteristics of plasma bubbles observed by TEC map

4. Summary

Outline

4. Summary

Outline

4. Summary

Outline

4. Summary

Outline

4. Summary

INTRODUCTION

Introduction

What are plasma bubbles?

Plasma Bubbles are equatorial plasma irregularities;

Are characterized to be a depletion of the ionosphericplasma density along the magnetic field lines;

It has serious implication in trans-ionosphericcommunications and navigation systems.

Introduction

Plasma bubbles signaturesAll Sky imager

EMBRACE

VHF radar

De Paula et al. (2011)Photometer

Pimenta (2005)

Introduction

EMBRACE

VHF radar

Pimenta (2005)

Introduction

EMBRACE

VHF radar

Pimenta (2005)

Introduction

Plasma bubbles signatures

Rockets - Langmuir probe

Muralikrishna (2006)

Ionosonde

Pimenta (2005)

Introduction

Plasma bubbles signatures

Rockets - Langmuir probe

Muralikrishna (2006)

Ionosonde

Pimenta (2005)

INSTRUMENTATION ANDMETODOLOGY

Instrumentation and Metodology

Measurement limitations

Most of the techniques mentioned above are not able to monitorplasma bubbles continuously in a sufficiently large twodimensional area.

All-sky imager - Depend on favorable weather conditions;

VHF radar and ionosonde - Cannot cover a wide range;

Rocket and Satellite - Only in situ measeruments;

Rocket - Sporadic launching.

TEC = Total Electron Content

TEC =satellite∫receiver

Ne · ds

TECU = 1016 eletrons/m2

Ne · ds

GNSS receivers

GNSS network N◦ of satellitesGPS 32

GLONASS 24Galileo 18BDS 22Total 96

-80 -75 -70 -65 -60 -55 -50 -45 -40 -35 -30

-35-30

-25-20

-15-10

5 RBMC RAMSAC LISN IGS

RBMC RAMSAC LISN IGS

Longitude (o)

Figueiredo (2017)

Square GPS (2017)

Receivers network N◦ of receiversLISN 30IGS 29

RAMSAC 67RBMC 101Total 227

GNSS receivers

GNSS network N◦ of satellitesGPS 32

GLONASS 24Galileo 18BDS 22Total 96

-80 -75 -70 -65 -60 -55 -50 -45 -40 -35 -30

-35-30

-25-20

-15-10

5 RBMC RAMSAC LISN IGS

Longitude (o)

Figueiredo (2017)

Square GPS (2017)

Receivers network N◦ of receiversLISN 30IGS 29

RAMSAC 67RBMC 101Total 227

TEC map

-80 -75 -70 -65 -60 -55 -50 -45 -40 -35 -30

-35-30

-25-20

-15-10

Longitude (o)

TEC map

TEC map analysis

TEC map can cover almost wholeSouth America and monitor TECvariability.

The spatial resolution varies from50-500 km.

TEC map has a time resolutionof 10 minutes.

TEC map analysis

Linear fitting over the minimumTEC values;

Latitudinal extension;

Inclination = angle between thelinear fitting and the geomagneticfield line.

TEC map analysis

Keograms

A keogram is a collection of west-east slices of TEC maps displayed in alongitude vs time diagram.

Keograms

A keogram is a collection of west-east slices of TEC maps displayed in alongitude vs time diagram.

Keogram analysis

Zonal drift velocity

vel =x(ti)− x(ti−1)

ti − ti−1[m/s]

Distance between adjacents bubbles

Dis = (xi − xi−1)[km]

Keogram analysis

ti − ti−1[m/s]

Keogram analysis

ti − ti−1[m/s]

We repeate this metodoly for eight different latitudes.

Keograms

We can investigate latitudinal gradients in zonal velocities anddistances in a large spatial range.

Keograms

We can investigate latitudinal gradients in zonal velocities anddistances in a large spatial range.

CHARACTERISTICS OFPLASMA BUBBLES OBSERVED

BY TEC MAP

Characteristics of plasma bubbles - TEC map

TEC map data base

TEC map data were analyzedbetween 11/2012 and01/2016;

Total of 597 nights;

Several plasma bubblessimultaneously.

TEC map data base

Frequency of occurrence of plasma bubbles

The largest number of plasmabubbles extends fromSeptember to March;

No occurrence of plasmabubbles can be seen from Mayto August due to the plasmabubbles criteria discussed.

Latitudinal extension of the plama bubbles and apex height

The extensions are larger inJanuary and December;

88% of cases the plasma bubblescan develop up to 20◦S.

Zonal drift velocities

Zonal velocities present a clearlatitudinal gradient;

v = 123 m/s at the Equator;

v = 65 m/s at 35◦S latitude.

Inter-bubble distances

Inter-bubble distances present aclear latitudinal gradient;

d = 920 km at the Equator;

d = 640 km at 30◦S latitude;

Distances greater than 2000 kmat the Equator.

Inclination of the plasma bubbles against geomagnetic field lines

Geomagnetic field lines;

θ+ = Tilted to the West;

θ− = Tilted to the East.

Nov./2012 − Jan./2016

Months

Jan Fev Mar Abr Mai Jun Jul Ago Set OutNovDez−12−10

In general, inclination of the plasma bubbles is larger in January andDecember;

∇U = U(0◦) - U(25◦S);

Good agreement with the monthly averaged zonal windgradient calculated from the HWM14.

Nov./2012 − Jan./2016

Months

∇U = U(0◦) - U(25◦S);

Nov./2012 − Jan./2016

Months

∇U = U(0◦) - U(25◦S);

Magnetic inclination vs Zonal wind gradient

Months

Jan Feb MarAprMay Jun Jul Aug Sep Oct NovDec−12−10

s)In general, inclination of the plasma bubbles is larger in January andDecember;

∇U = U(0◦) - U(25◦S);

Summary

EPBs occurred mainly from September to March. The latitudinal extensionof the EPBs is larger for the months of January and December. In 88% ofthe cases the EPBs developed up to 20◦S, indicating that the apex heightwas of 777 km altitude;

EPB zonal drift velocities presented a clear latitudinal gradient varying from123m/s at the Equator to 65m/s at 35◦S;

The inter-bubble distances also showed a clear latitudinal gradient varyingfrom 920 km at the Equator to 640 km at 30◦S;

The latitudinal extension of EPBs occasionally presents a significantinclination against the geomagnetic field lines;

Summary

Thank you!

characteristics of equatorial plasma bubbles observed by ...diego barros | april/2017 plasma bubles...

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