Perturbations of Perturbations of the terrestrial low the terrestrial low ionosphere caused ionosphere caused

by solar flaresby solar flares

Aleksandra NinaInstitute of Physics, Belgrade, Serbia Institute of Physics, Belgrade, Serbia

ContentsContents

• Ionosphere

• Significance of its studySignificance of its study

• VLF signals – “ionospheric probes”VLF signals – “ionospheric probes”

• Belgrade VLF station

• Analyze of low ionosphere response to the solar X-flares

IntroductionIntroduction

• Terrestrial ionosphere• Methods• This talk: experimental and

theoretical research of the perturbations of low ionosphere

(D region)

Significance Significance • ScienceScience

- ionospheric diagnostics

- study of physical and chemical processes

- detection of different pure natural and man-induced events:

1. processes in the Sun

2. processes in the outer spaces

3. processes in the Earth

• TelecommunicationsTelecommunications• - radio communications,

• - planned networks of mobile communications satellites, • - high precision applications of global navigation satellite systems,

etc.

Solar flares and CMEGRB

Lightning Terrestrial Gamma-Ray FlashesNuclear testsEarthquakes Vulcan eruptions

VLF signals – VLF signals – “ionospheric probes”“ionospheric probes”

• Numerical programs: LWPCLWPC, ModeFinderModeFinder

• Advantage: - continual emission - large space that can be analyzed• VLF networks -transmitters -receivers: AWESOMEAWESOME,

AbsPALAbsPAL, SAVNETSAVNET, AARDDVARKAARDDVARK

Belgrade VLF station on Belgrade VLF station on Institute of Physics Institute of Physics

• AbsPalAbsPal- electrical antenna- works as of 2004- simultaneously records 6

signals • AWESOMEAWESOME((Atmospheric Weather Electromagnetic System for Observation Modeling and Education))- two magnetic loop antennas- works as of 2008- simultaneously records 15

signals VLF receiver systems

at Belgrade station

AbsPALAbsPAL AWESOMEAWESOME

Solar X-flare perturbationsSolar X-flare perturbations• Theoretical model: Wait’s model of ionosphere:Wait’s model of ionosphere: reflection height H’ and sharpness β• Numerical program for simulation VLF

signal propagation:

LWPCLWPC (Long-Wave Propagation Capability)::- Input parameters: β and H’ - Output: ALWPC and PLWPC

- Unperturbed ionosphere:

β = 0.3 km-1 H’=74 km

- Perturbed ionosphere:

determination of β and H’

14:05 14:10 14:15 14:20 14:25

52

54

56

58

60

24

26

28

30

10-6

10-5

14:05 14:10 14:15 14:20 14:25

Time (UT)

rec (

o)

Are

c (d

B)

I(W

/m2 )

GOES-15 fit

14:05 14:10 14:15 14:20 14:25

0,3

0,4

0,5

0,6

68

70

72

74

14:05 14:10 14:15 14:20 14:25

(k

m-1)

t (UT)

modeling fit

H' (

km)

modeling fit

Case: -February 18th, 2011

- Recording:- GOES-15 satellite- Belgrade AWESOME receiver- DHO (Germany) transmitter (23.4 kHz) 14:05 14:10 14:15 14:20 14:25

109

1010

1011

N (m

-3)

Time (UT)

httHt eehtN 15.0'131043.1),(

recLWPC AA recLWPC PP

Ionospheric response Ionospheric response (preliminary results)(preliminary results)

G(t) – electron gain rate

L(t) – electron loss rate

Upper half of D region:

tLtGdt

dN

)()()( 00 tItIKPtPtG sss

tNttRtL eff2

P(t) – photo-ionization rateR(t) – recombination rateI(t) – radiation flux by satelliteαeff – effective recombination coefficientKs – coefficient (dependent on energy interval of data registered by satellite)

14:05 14:10 14:15 14:20 14:25

0

1x1010

2x1010

3x1010

4x1010

5x1010

6x1010

dN

/dt (m

-3s-1

)

Time (UT)

total P R

I II III

I - Quasi equilibrium regime

II - Photo-ionization regime

III - Recombination regime

ConclusionsConclusions• The applications of the low ionospheric

investigations in science and information technologies

• Research of low ionosphere by VLF waves• Presentation of Belgrade VLF station• Experimental and theoretical analyzes of the low

ionospheric response to particular solar X-flares - electron concentration - electron gain and electron loss rates (preliminary results)

PerturbersPerturbers• Solar radiation

- regular variation

- transient variations

• Outer space

• Terrestrial

21:30:00 21:30:20 21:30:40 21:31:00

58.0

58.5

59.0

59.5

-130

-125

-120

-11521:30 21:30 21:30 21:31

Am

plit

ud

e (

dB

)

NAA

GRB December 27th, 2004

Ph

ase

(o)

Time (UT)00:00 04:00 08:00 12:00 16:00 20:00 24:0010

20

30

40

10

20

30

40

10

20

30

40

10

20

30

4000:00 04:00 08:00 12:00 16:00 20:00 24:00

Time (UT)

Mart 21, 2011 Mart 22, 2011 Mart 23, 2011

Am

plit

ud

e (

dB

)

December 21, 2010 December 22, 2010 December 23, 2010

September 22, 2010 September 23, 2010 September 24, 2010

Jun 13, 2010 Jun 19, 2010 Jun 20, 2010

DHO

HESSI

06:00 08:00 10:00 12:00 14:00 16:000

5

10

15

20

10

20

30

0

5

10

15

2006:00 08:00 10:00 12:00 14:00 16:00

Am

plit

ude (

dB

)

Time (UT)

NAA

DHO

16_February_2011

1-8A GOES-15

Inte

nsi

ty (

10-6

W/m

2 )

SGR 1806-20

00:42 00:44 00:46 00:48

-170

-165

-160

-155

18

19

20

21

-160

-155

-150

-145

-140

-135

23

24

25

26

2700:42 00:44 00:46 00:48

Ph

ase

(o)

Time (UT)

GQD

Am

plit

ud

e (

dB

)

GQD

Ph

ase

(o) DHO

Am

plit

ud

e (

dB

)

DHO