Post on 20-Dec-2015
Morphological features of the Morphological features of the spectral resonance structures at spectral resonance structures at
different latitudesdifferent latitudes
N.V. SemenovaN.V. SemenovaPolar Geophysical Institute, Apatity, Russia
Examples of Spectral Resonance Structure (SRS) observed inSodankyla Geophysical Observatory (L ~ 5.2) during two
successive days
The existence of the IAR causes resonance features of the ionosphere reflection coefficient
0 1 2 3 4 5Frequency, H z
0.0
0.2
0.4
0.6
0.8
1.0
Ref
lect
ion
Coe
ffici
ent
F1
F2
Dependence of the frequency interval of IAR (F) on ionospheric parameters
The theory of IAR The theory of IAR predicts dependence of predicts dependence of the SRS characteristics the SRS characteristics on parameterson parametersof upper ionosphereof upper ionosphere
)(
)(
hLan2
kc
kf 4
1
F = f k + 1 - f k = )( hLan2c
w h e r e c i s v e l o c i t y o f l i g h t , L i s e f f e c t i v e t h i c k n e s s o ft h e F - l a y e r , h i s t h i c k n e s s o f t h e F - l a y e r m a x i m u m , n a
i s t h e A l f v e n r e f r a c t i v e i n d e x a t t h e h e i g h t o f t h e F -l a y e r m a x i m u m .
50e
N0H
4ca
n .~
w h e r e H 0 - m a g n e t i c f i e l d , – p l a s m a d e n s i t y , N e - t h ee l e c t r o n d e n s i t y .
Morphological features of the Morphological features of the Spectral Resonance StructuresSpectral Resonance Structures at at
mid-latitudesmid-latitudes
Nizhny Novgorod
Examples of magnetic variation spectra observed at mid-latitude in the nighttime and daytime in the years of solar
activity minimum
The total number of observation The total number of observation days in half-year intervals days in half-year intervals
Probability of the SRS observation in 6-month intervals during the solar activity cycle
Variation of the number of Variation of the number of sunspots during the solar sunspots during the solar activity cycle averaged activity cycle averaged
over 6 months over 6 months
Morphological features of the Morphological features of the Spectral Resonance StructuresSpectral Resonance Structures at high at high
latitudes latitudes
Sodankyla Geophysical ObservatorySodankyla Geophysical Observatory
Examples of Spectral Resonance Structure observed inSodankyla Geophysical Observatory during two successive days
012
012
012
012
012
F, H
z
012
012
012
0 - 3 U T
3 - 6 U T
6 - 9 U T
9 - 12 U T
12 - 15 U T
15 - 18 U T
18 - 21 U T
21 - 24 U T
June 95 June 96 June 97 June 98 June 99
The SRS frequencyThe SRS frequencyinterval (interval (F) depends onF) depends on: • local timelocal time• seasonseason• solar activitysolar activity
0
1
0
1
0
1
0
1
Pro
babi
lity
0
1
0
1
0
1
0
10 - 3 U T
3 - 6 U T
6 - 9 U T
9 - 12 U T
12 - 15 U T
15 - 18 U T
18 - 21 U T
21 - 24 U T
June 95 June 96 June 97 June 98 June 99
The SRS occurrence rateThe SRS occurrence ratedepends on:depends on:• local timelocal time• seasonseason• solar activitysolar activity
Morphological features of the Morphological features of the Spectral Resonance StructuresSpectral Resonance Structures at low at low
latitudes latitudes
Island of Crete, GreeceIsland of Crete, Greece
Morphological features of the Morphological features of the Spectral Resonance StructuresSpectral Resonance Structures at at
high latitudeshigh latitudes
Barentsburg, Spitsbergen
The number of observation days and probability of SRS observation as a function of season
0
10
20
30
40
nu
mb
er
of d
ays
0.0
0.2
0.4
0.6
0.8
1.0
pro
ba
bili
ty
Jul 02 O ct 02 Jan 03 Apr 03 Jul 03 O ct 03 Jan 04
Dependence of the F on season 0 - 3 UT
3 - 6 UT
6 - 9 UT
9 - 12 U T
12 - 15 U T
15 - 18 U T
18 - 21 U T
21 - 23 U T
Jul 02 O ct 02 Jan 03 Apr 03 Ju l 03 O ct 03 Jan 04
0.00.40.8
0.00.40.8
0.00.40.8
0.00.40.8
0.00.40.8
0.00.40.8
F, H
z
0.00.40.8
0.00.40.8
0 1 2 3 4 5
0.0
0.5
1.0
Ref
lect
ion
Coe
ffici
ent
0 1 2 3 4 5Frequency, H z
0.0
0.5
1.0
Ref
lect
ion
Coe
ffici
ent
June 1995
D ecem ber 1995
June 1999
D ecem ber 1999
100 1000 10000 100000 1000000Electron D ensity, cm -3
0
500
1000
1500
2000
Alti
tude
, km
June 1995
Decem ber 1995
June 1999
Decem ber 1999
Model ionospheric profiles and calculated reflection coefficientsfor different conditions