Quiet-time F2-layer Disturbances: Quiet-time F2-layer Disturbances: Morphology and some Formation Morphology and some Formation Mechanisms Mechanisms Andrei Mikhailov Andrei Mikhailov Institute of Terrestrial Magnetism Ionosphere and Radio Wave Propagation (IZMIRAN) Russian Academy of Sciences
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Quiet-time F2-layer Disturbances: Morphology and some Formation Mechanisms Quiet-time F2-layer Disturbances: Morphology and some Formation Mechanisms Andrei.
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Quiet-time F2-layer Disturbances: Quiet-time F2-layer Disturbances: Morphology and some Formation Morphology and some Formation
Mechanisms Mechanisms
Andrei MikhailovAndrei Mikhailov
Institute of Terrestrial Magnetism Ionosphere and Radio Wave Propagation
is a special class of the F2-layer is a special class of the F2-layer perturbations not related to perturbations not related to
geomagnetic activitygeomagnetic activity
1.Their amplitude is comparable to moderate F2-layer storm
effects resulted from increased geomagnetic activity
2. Their morphology is different from the morphology of
usual storm-induced F2-layer disturbances
3. The formation mechanisms are also different
(for Negative disturbances)
Specification of Q-disturbances used in the Specification of Q-disturbances used in the analysisanalysis
1. (NmF2/NmF2med – 1)x100% ≥ 40% If all 3-h ap indices were ≤ 7 for the preceding 24 hours
2. A 27-day NmF2 running median centered to the day in question
3. Only long-lasting, ≥ 3-h disturbances were considered
4. =NmF2/NmF2med were used
An example of negative Q-disturbanceAn example of negative Q-disturbance
5 .5
5 .7
5 .9
6 .1
6 .3
log
Nm
F2,
cm
M o sc o w , A p r 2 1 -2 4 , 1 9 8 0
-3
A p r 2 1 A p r 2 2 A p r 2 3 A p r 2 4
.
.
0 24 4 8 7 2 96U T , h o u rs
30 0
34 0
38 0
42 0
46 0
hmF
2, k
m
A p = 5 A p = 9 A p = 6 A p = 7
.
An example of positive Q-disturbanceAn example of positive Q-disturbance
M o sc o w , A p r 0 6 -0 9 , 1 9 7 3-3
0 24 4 8 7 2 96
4 .6
4 .8
5 .0
5 .2
5 .4
5 .6
5 .8
6 .0
log
Nm
F2,
cm
A p r 0 6 A p r 0 7 A p r 0 8 A p r 0 9
.
0 24 4 8 7 2 96U T , h o u rs
22 0
26 0
30 0
34 0
38 0
hmF
2, k
m
A p = 4 A p = 4 A p = 8 A p = 7
.
Seasonal occurrence frequency variation forSeasonal occurrence frequency variation for negative usual and Q-disturbances negative usual and Q-disturbances
1 2 3 4 5 6 7 8 9 10 11 12M o n th s
0
4
8
12
16
20
24
28
Occ
uren
ce, %
M ax (N = 2 0 6 )
M ed (N = 2 5 3 )
M in (N = 1 8 2 )
(0 9 -1 5 ) L T
.
.
1 2 3 4 5 6 7 8 9 10 11 12M o n th s
0
5
10
15
20
25
30
35
40
Occ
urre
nce,
%
A ll so la r ac tiv itylev e l (N = 7 5 )(0 9 -1 5 ) L T
Q -d is tu rb a n cesU su a l d is tu rb a n ce s
.
Latitudinal occurrence frequency variation forLatitudinal occurrence frequency variation for Negative and Positive usual and Q-disturbances Negative and Positive usual and Q-disturbances
(0 9 -1 5 ) L T S e c to r
A ll n e g a tiv e d is t.N eg a tiv e Q -d is t.
2 0 3 0 4 0 5 0 6 0 7 0In v a ria n t la ti tu d e , d e g
0 .0
0 .2
0 .4
0 .6
0 .8
1 .0
1 .2
Per
cent
of
tim
e
(0 9 -1 5 ) L T S e c to r
A ll p o s itiv e d is t.P o s itiv e Q -d is t.
2 0 3 0 4 0 5 0 6 0 7 0In v a ria n t la ti tu d e , d e g
0 .0
0 .2
0 .4
0 .6
0 .8
1 .0
Per
cent
of
tim
e
(1 6 -2 2 ) L T S e c to r
A ll n e g a tiv e d is t.N eg a tiv e Q -d is t.
2 0 3 0 4 0 5 0 6 0 7 0In v a ria n t la ti tu d e , d e g
0 .0
0 .4
0 .8
1 .2
1 .6
2 .0
2 .4
Per
cent
of
tim
e
(1 6 -2 2 ) L T S e c to r
A ll p o s itiv e d is t.P o s itiv e Q -d is t.
2 0 3 0 4 0 5 0 6 0 7 0In v a ria n t la ti tu d e , d e g
0 .0
0 .4
0 .8
1 .2
1 .6
2 .0
2 .4
Per
cent
of
tim
e
2-D distribution of NmF2/NmF22-D distribution of NmF2/NmF2medmed in the case of in the case of
Positive Q-disturbance Positive Q-disturbance
0 60 120 180 240 300 360
G eodetic lon g itu de , deg
2 0
3 0
4 0
5 0
6 0
7 0
Inva
rian
t lat
itu
de, d
egP o sitiv e Q -d istu rb a n ce A p r 0 6 , 1 9 7 3
Notice latitudinal dependence for NmF2/NmF2med variations
2-D distribution of NmF2/NmF22-D distribution of NmF2/NmF2medmed in the case of in the case of
Negative Q-disturbance Negative Q-disturbance
0 60 120 180 240 300 360
G eodetic lon g itu de , deg
2 0
3 0
4 0
5 0
6 0
7 0
Inva
rian
t lat
itu
de, d
eg
N eg a tiv e Q -d istu rb a n ce J a n 0 6 , 1 9 7 0
Longitudinal variations of the NmF2/NmF2med ratio under Q-disturbance events
P o sitiv e Q -d istu rb a n ce A p r 0 6 -0 9 , 1 9 7 3
In v a r. L a t = 6 0 (1 1 -1 4 L T )
0 60 1 20 1 80 240 300 36 0G e o d e tic lo n g itu d e , d e g
0 .8
1 .0
1 .2
1 .4
1 .6
1 .8
2 .0
2 .2
Nm
F2/
Nm
F2 m
ed
A p r 6A p r 7A p r 8A p r 9
0 60 1 20 1 80 240 300 36 0G e o d e tic lo n g itu d e , d e g
0 .5
0 .6
0 .7
0 .8
0 .9
1 .0
Nm
F2/
Nm
F2 m
ed
Jan 6Jan 7Jan 8
N eg a tiv e Q -d istu rb a n ce J a n 0 6 -0 8 , 1 9 7 0
In v a r. L a t = 6 0 (1 1 -1 4 L T )
Steep front
Steep front
Physical Physical InterpretationInterpretation
Positive and Negative Q-disturbances observedPositive and Negative Q-disturbances observed
by Millstone Hill ISR by Millstone Hill ISR
5 .8
6 .0
6 .2
6 .4
6 .6
log
Nm
F2
A p r 1 1 , 2 0 0 0A p r 1 2 , 2 0 0 0M e d ia n
1 3 1 5 1 7 1 9 2 1 2 3U T , h o u rs
2 8 0
3 0 0
3 2 0
3 4 0
3 6 0
hmF2
, km
P o sitiv e Q -d is tu rb an ce
A p r 1 6 , 2 0 0 2A p r 1 5 , 2 0 0 2M e d ia n
5 .8
6 .0
6 .2
6 .4
log
Nm
F2
1 3 1 5 1 7 1 9 2 1 2 3U T , h o u rs
2 6 0
2 8 0
3 0 0
3 2 0
3 4 0
hmF2
, km
N e g a tiv e Q -d is tu rb an c e
Date Tex (K)
log [O]300 (cm-3)
log [O2]300 (cm-3)
log [N2]300 (cm-3)
log300 (s-1)
W (m/s)
Apr 11 1457 1312
9.019 9.095
7.150 6.884
8.602 8.588
-3.309 0
Apr 12 1427 1303
8.751 9.094
7.102 6.848
8.519 8.568
-3.381 7.6
Apr 15 1447 1344
8.889 9.078
6.866 6.921
8.404 8.588
-3.511 1.0
Apr 16 1439 1326
8.667 9.073
6.824 6.891
8.311 8.570
-3.624 -7.1
lgNmF2 = 4/3lg[O] - 2/3lg + 1/2lgTn
Both Positive and Negative Q-disturbances are mainly due to [O] variations presumably resulted from the vertical gas
motion in the whole thermosphere
Retrieved Aeronomic Parameters at 300 km for Positive (Apr 11, Retrieved Aeronomic Parameters at 300 km for Positive (Apr 11, 2000) and Negative (Apr 16, 2002) Q-disturb. 2000) and Negative (Apr 16, 2002) Q-disturb.
Second line (Italic) – NRLMSISE-00 model values Second line (Italic) – NRLMSISE-00 model values
Negative daytime Q-disturbances Negative daytime Q-disturbances correspond to low [O] and an enhanced correspond to low [O] and an enhanced
Monthly Ap indices and number (in brackets) of negative disturbances observed at Slough for three months and
years around solar minimum.
A sketch to illustrate the place of Q-disturbances A sketch to illustrate the place of Q-disturbances on the Ap index scaleon the Ap index scale
0 5 1 0 1 5 2 0 2 5 3 0A p
0 .0
0 .5
1 .0
1 .5
2 .0
Nm M ed ia n
Neg
ativ
eQ
-dis
turb
ance
sar
eaPo
sitiv
eQ
-dis
turb
ance
sar
ea
L o n g -d u ra tio np o sitiv e d is tu rb an ce sa rea
U su a ln e g a tiv ed is tu rb an ce sa rea
The Ground State of the ThermosphereThe Ground State of the Thermosphere
The Ground State corresponds to a very low The Ground State corresponds to a very low geomagnetic activity with an unconstrained geomagnetic activity with an unconstrained
solar-driven (poleward) thermospheric solar-driven (poleward) thermospheric circulation and low [O] at middle and circulation and low [O] at middle and
subauroral latitudes. subauroral latitudes.
This follows from the model calculations by Rishbeth and Müller-Wodarg (1999)
Retrieved Aeronomic Parameters at 300 km forRetrieved Aeronomic Parameters at 300 km for Apr 15, 16, 18, 2002 Apr 15, 16, 18, 2002
Italic – Millstone Hill Tex estimates Italic – Millstone Hill Tex estimates
Dates Tex log[O]300 log300 W
Apr 16/15, 2002 -36 -0.196 -0.105 -2.8
Apr 18/15, 2002 +13 +0.06 +0.147 +8.8
Variations of aeronomic parameters for the two pairs of dates
A contribution of the main parameters to hmF2 A contribution of the main parameters to hmF2 variationsvariations
][][;/
54.0loglog]log[
3
3.2
2221
2
ONmgkTH
cWd
HO
Hhm
n
All controlling parameters: log[O], log, Tn, and W
are < 0 for Q-disturbance decreasing hmF2, [O] providing the main contribution
and these parameter contributions
are > 0 for Storm-induced disturbance increasing hmF2, the [O] contribution being small due to the competition between Tn increase and storm-induced thermospheric circulation
Different Ne(h) distributionsDifferent Ne(h) distributions
10 0
20 0
30 0
40 0
50 0
60 0
70 0
Hei
ght,
kmA p r 1 5 , 2 0 0 2A p r 1 6 , 2 0 0 2A p r 1 8 , 2 0 0 2
5 .0 5 .2 5 .4 5 .6 5 .8 6 .0 6 .2 6 .4L o g N e , cm -3
10 0
20 0
30 0
40 0
50 0
60 0
Hei
ght,
km
M a r 1 7 , 1 9 9 0M ar 2 2 , 1 9 9 0
R efe ren c e d ay
R efe ren c e d ay
The difference in Ne(h) distributions results from The difference in Ne(h) distributions results from different plasma temperatures, i.e. plasma scale heights different plasma temperatures, i.e. plasma scale heights
dh
TTd
TTTTk
gmH ie
ieie
ip
)(1
)(1
Observed at Millstone Hill plasma temperatures, their gradient and plasma scale heights at 500 km for quiet and disturbed days.