neutral density variations within the southern auroral oval
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Neutral Density Variations Within the Southern Auroral Oval. Bruce R Bowman HQ AFSPC/A9AC. DOD Distribution A Approved for public release Distribution unlimited. Acknowledgement. - PowerPoint PPT PresentationTRANSCRIPT
Neutral Density VariationsWithin the Southern Auroral Oval
Bruce R BowmanHQ AFSPC/A9AC
DOD Distribution AApproved for public release
Distribution unlimited
DOD Distribution AApproved for public release
Distribution unlimited
Presentation Title 2Presentation Date
Acknowledgement
I would like to thank Janet Green of the Space Weather
Prediction Center for providing the NOAA/POES space
environment monitoring data from the NOAA satellites.
Presentation Title 3Presentation Date
Introduction
• Decay of high eccentricity satellite 16125 with perigee location in the southern hemisphere
• Neutral density variations during pre-storm period
• Neutral density variations during storm period
• Southern auroral oval variations during storm period
• Conclusions
Presentation Title 4Presentation Date
Last 20 Days of Orbital Decay
16125 Perigee and Apogee Heights
105
110
115
120
125
130
135
140
145
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
2001 Day
Pe
rig
ee
Ht
(km
)
0
500
1000
1500
2000
2500
3000
3500
4000
Ap
og
ee
Ht
(km
)
Presentation Title 5Presentation Date
Orbital Drag at Perigee
16125 ΔTime Since Perigee Passage
110
115
120
125
130
135
140
145
150
155
160
165
170
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Minutes Since Perigee Passage
Orb
ita
l H
eig
ht
(km
)
95 % Orbit Drag
80 % Orbit Drag
Δlong = -15° Δlong = +15°
Presentation Title 6Presentation Date
Orbit Perigee Location
16125 Perigee Latitude and Local Solar Time
-80
-70
-60
-50
-40
-30
-20
-10
0
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
2001 Year Day
Pe
rig
ee
La
titu
de
(d
eg
)
0
3
6
9
12
15
18
21
24
Pe
rig
ee
LS
T (
HH
)
Presentation Title 7Presentation Date
Storm Indices ap and Dst Prior to Orbit Decay
Geomagnetic Indices
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
40 41 42 43 44 45 46 47 48 49 50
2001 Day
ap
an
d D
st
Dst
ap
Presentation Title 8Presentation Date
HALO CME C3 HALO CME C3
Presentation Title 9Presentation Date
Pre-Storm Density Variations by Time
16125 ΔRho at Lat -57°, Ht 118 km, LST 3 Hr
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
40.5 41.0 41.5 42.0 42.5 43.0
2001 Day
DR
ho
(%
)
-25
0
25
50
75
100
125
150
175
200
ap
an
d -
Ds
t
- Dst ap
Presentation Title 10Presentation Date
Pre-Storm Density Variations by Longitude
16125 ΔRho (Using Daily Aves) for Pre-Storm Days 041-043
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
0 30 60 90 120 150 180 210 240 270 300 330 360
Longitude E (deg)
DR
ho
(%
)
DAY 041
DAY 042
DAY 043
Presentation Title 11Presentation Date
Day 042 Pre-Storm Perigee Passage
90°
0°
270°
180°
ω
Presentation Title 12Presentation Date
Storm Density Variations by Time
16125 ΔRho at Lat -57°, Ht 118 km, LST 3 Hr
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
43 44 45 46 47 48 49
2001 Day
DR
ho
(%
)
-25
0
25
50
75
100
125
150
175
200
ap
an
d -
Ds
t
- Dst ap
Presentation Title 13Presentation Date
Storm Density Variations by Longitude
16125 ΔRho (Using Daily Aves) for Day 044-048 by Longitude E
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
0 30 60 90 120 150 180 210 240 270 300 330 360
Longitude E (deg)
DR
ho
(%
)
DAY 44DAY 45DAY 46DAY 47DAY 48
Presentation Title 14Presentation Date
Day 044/2243 UT - Density High
270°
0°
90°
180°
270°
90°
180° 0°
ω
Presentation Title 15Presentation Date
Day 045/0544 UT - Density High
270°
0°
90°
180°
270°
180° 0°
90°
ω
Presentation Title 16Presentation Date
Day 045/ 2318 UT - Density High
270°
0°
90°
180°
270°
180°
90°
0°
ω
Presentation Title 17Presentation Date
Day 046/ 0614 UT - Density High
270°
0°
90°
180°
ω
270°
180°
90°
0°
Presentation Title 18Presentation Date
Day 045/ 1617 UT - Density Low
270°
0°
90°
180°
270°
180°
90°
0°ω
Presentation Title 19Presentation Date
Day 046/ 1451 UT - Density Low
270°
0°
90°
180° ω
270°
180°
90°
0°
Presentation Title 20Presentation Date
Day 047/ 1442 UT - Density Low
270°
0°
90°
180° ω
270°
180°
90°
0°
Presentation Title 21Presentation Date
Day 048 End of Storm Perigee Passage
270°
90°
0°180°
ω
Presentation Title 22Presentation Date
Storm Density Variations
16125 ΔRho at Lat -57°, Ht 118 km, LST 3 Hr
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
43 44 45 46 47 48 49
2001 Day
DR
ho
(%
)
-25
0
25
50
75
100
125
150
175
200
ap
an
d -
Ds
t
- Dst ap
76° 64° 84°
143° 162° 187° 143°
Long E Initial High:
Long E Mid Low:
59° 43°
16125 ΔRho at Lat -57°, Ht 118 km, LST 3 Hr
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
43 44 45 46 47 48 49
2001 Day
DR
ho
(%
)
-25
0
25
50
75
100
125
150
175
200
ap
an
d -
Ds
t
- Dst ap
76° 64° 84°
143° 162° 187° 143°
Long E Initial High:
Long E Mid Low:
59° 43°
Presentation Title 23Presentation Date
Storm Response Summary
• Density response shows no more than 2hr lag from storm commencement
• ~15% rise in density at density high longitudes
• ~15% drop in density at density low longitudes
• Density low values are more persistent as density highs drop as storm subsides
Presentation Title 24Presentation Date
Conclusions
• Density variations accurate to ~5% can be obtained from orbital drag analysis using accurate radar tracking data either side of the perigee passage.
• Neutral density variations within the southern hemisphere auroral oval can be obtained from decays of high eccentricity satellite orbits.
• This unique data set implies unmodeled longitudinal variations in neutral density in the lower thermosphere auroral zone.
• Additional satellite decays are available for further analysis of density variations within the lower thermosphere.
Presentation Title 25Presentation Date
Backup Slides
Presentation Title 26Presentation Date
16125 Orbital Height History
16125 Perigee and Apogee Height History
0
500
1000
1500
2000
2500
3000
3500
4000
4500
85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102
Year
Pe
rig
ee
He
igh
t (k
m)
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
Ap
og
ee
He
igh
t (k
m)