AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics...
-
Upload
lyndsey-brownson -
Category
Documents
-
view
214 -
download
0
Transcript of AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics...
![Page 1: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/1.jpg)
AN ELECTRON DENSITY PROFILE AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN MODEL FOR THE SOUTH AFRICAN
IONOSPHEREIONOSPHERE
Lee-Anne McKinnell
Physics Department, Rhodes University, Grahamstown, South Africa
Space Physics Group, Hermanus Magnetic Observatory (HMO), Hermanus, South Africa
![Page 2: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/2.jpg)
South African Ionosonde Network
Grahamstown(33.3ºS, 26.5ºE)
Louisvale(28.5ºS,21.2ºE)
(22.4ºS, 30.9ºE )Madimbo
Hermanus(34.4ºS, 19.2ºE)
1973 – 2008N(h) profiles from 1996
2000 – 2008
2000 – 2008
Installed June 2008
![Page 3: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/3.jpg)
Neural Networks
Training a computer to learn the relationship between a given set of inputs and a corresponding output
highly suitable for non-linear relationships
Main requirement -- an archived database describing the history of the relationship
South African region Grahamstown, n(h) profile data from 1996, characteristics from 1973 Louisvale & Madimbo, n(h) profile data from 2000
![Page 4: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/4.jpg)
SABIM Model
• South African region
• Bottomside ionospheric model
• Electron density profile
• Several NNs combined
Special Features
• F1 Probability Network
• Smoothing technique
Criterion for optimisation
• rms error on individual parameters
• Ability to reproduce realistic profiles
![Page 5: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/5.jpg)
0
20
40
60
80
100
120
140
160
180
200
220
1973 1977 1981 1985 1989 1993 1997 2001 2005
Year
R2
Grahamstown 3 ionosondes
Solar Activity
![Page 6: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/6.jpg)
SABIMSouth African
Bottomside Ionospheric Model
Day Number
Solar Activity
Hour
Magnetic Activity
ElectronDensityProfile
Model
Geomagneticposition info
Neural Network basedempirical ionospheric model
for theSouth African region
![Page 7: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/7.jpg)
E layer Profile
Is E layer predictable?E limits NN
Predict E layerfoE, hmE,
E profile NNs
Determining the probability of an F1 layer
F1 Probability NNOutput determines 1) or 2) or 3)
1) No F1 layerF2NN
2) F1 layer definiteF1F2NN
3) F1 layer in L conditionL Algorithm
Smoothing Technique
The Model
F layer Profile
F2 Layer NetworkIncluded
Peak parameters – foF2, hmF2Chebyshev coefficients
Profile constructedfoF2 – global foF2 network used
F1 Layer NetworkIncluded
Peak parameters – foF1, hmF1Chebyshev coefficients
Profile constructedL-algorithm,
weighted avg btn F1 and No F1
![Page 8: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/8.jpg)
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25
hour, [ut]
fof2
, [M
Hz]
Summer
Winter
Louisvale -- Low Solar
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25
hour, [ut]
fof2
, [M
Hz]
Summer
Winter
Grahamstown -- Low Solar
0
1
2
3
4
5
6
7
8
9
0 5 10 15 20 25
hour, [ut]
fof2
, [M
Hz]
Summer
Winter
Madimbo -- Low Solar
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25
hour, [ut]
fof2
, [M
Hz]
Summer
Winter
mid point -- Low Solar
Diurnal foF2 variations
![Page 9: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/9.jpg)
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
5.3
5.5
0 50 100 150 200 250 300 350
Day Number
foF
1, [
MH
z]
measured
predicted
Madimbo
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
5.3
5.5
0 50 100 150 200 250 300 350
Day Number
foF
1, [
MH
z]
measured
predictedLouisvale
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.1
5.3
5.5
0 50 100 150 200 250 300 350
Day Number
foF
1, [
MH
z]
measured
predictedGrahamstown
foF1 variations
2007
10h00 UT
foF1
![Page 10: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/10.jpg)
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 50 100 150 200 250 300 350
Day Number
foE
, [M
Hz]
measured
predicted
Madimbo
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 50 100 150 200 250 300 350
Day Number
foE
, [M
Hz]
measured
predicted
Louisvale
2.4
2.6
2.8
3
3.2
3.4
3.6
3.8
4
0 50 100 150 200 250 300 350
Day Number
foE
, [M
Hz]
measured
predictedGrahamstown
2007
10h00 UT
foE
foE variations
![Page 11: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/11.jpg)
80
130
180
230
280
330
2 4 6 8 10 12 14frequency, [MHz]
hei
gh
t, [
km]
Actual
SABIM
IRI2001
Louisvale
DN=90, R=113
80
130
180
230
280
330
2 4 6 8 10frequency, [MHz]
hei
gh
t, [
km]
Actual
SABIM
IRI2001
Madimbo
DN=340, R=105
80
100
120
140
160
180
200
220
240
260
280
2 3 4 5 6 7 8frequency, [MHz]
hei
gh
t, [
km]
Actual
SABIM
IRI2001
Grahamstown
DN=93, R=17
Predicted profiles
80
130
180
230
280
2 4 6 8 10frequency, [MHz]
hei
gh
t, [
km]
Actual
SABIM
IRI2001
Grahamstown
DN=186, R=120
![Page 12: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/12.jpg)
foE
hmE
foF1
hmF1
Summer
10h00 UT Contour Plots
![Page 13: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/13.jpg)
foE
hmE
foF1
hmF1
Winter
10h00 UT Contour Plots
![Page 14: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/14.jpg)
10h00 UT Contour Plots
foF2
foF2
hmF2
hmF2
Winter
Summer
![Page 15: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/15.jpg)
F1 Probability
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
3.5 4 4.5 5 5.5 6 6.5 7 7.5
Hour, UT
Pro
bab
ilit
y
P(N)
P(L)
P(F)
Summer, High R
No F1 F1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
13.5 14 14.5 15 15.5 16 16.5 17 17.5
Hour, UT
Pro
bab
ilit
y P(N)
P(L)
P(F)
Summer, High R
No F1 F1
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
3.5 5.5 7.5 9.5 11.5 13.5 15.5 17.5
Hour, UT
Pro
bab
ilit
y
P(N)
P(L)
P(F)
Autumn, High R
No F1No F1
![Page 16: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/16.jpg)
80
130
180
230
280
330
2 3 4 5 6 7 8 9 10
frequency, MHz
hei
gh
t, k
m
Max
Min
DN = 27, HR = 10h00, R = 83, A = 3.81
Grahamstown
Uncertainty
![Page 17: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/17.jpg)
Future Plans
• extend SABIM to include Hermanus data
• update every 2 years
• use manually obtained F1 information for F1 probability network
• expand uncertainty network
![Page 18: AN ELECTRON DENSITY PROFILE MODEL FOR THE SOUTH AFRICAN IONOSPHERE Lee-Anne McKinnell Physics Department, Rhodes University, Grahamstown, South Africa.](https://reader033.fdocuments.us/reader033/viewer/2022051614/5517e556550346d0568b46c0/html5/thumbnails/18.jpg)