Post on 04-Feb-2016
description
Tidal Structures in the Equatorial Ionosphere
C. Y. Huang1, S. H. Delay2, E. K. Sutton1, and P. A. Roddy1,
1Air Force Research Laboratory2Boston College
MURI Workshop28 October 2010
Outline
• Broad Plasma Decreases (BPDs) in C/NOFS PLP – description
• Detrending C/NOFS PLP plasma densities - procedure
• Statistical analysis of detrended plasma densities for June 2008
• GRACE neutral density residuals for June 2008
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Communication/Navigation Outage Forecast System
• Launched May 2008 into low-inclination orbit
• Goal is forecasting of scintillation
• 5 experiments – Planar Langmuir Probe– Vector Electric Field Investigation– Ion Velocity Monitor / Neutral Wind Monitor– RF Beacon– GPS
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Simultaneous Broad Plasma Decreases C/NOFS and DMSP22 – 23 UT, 19 June 2008
C/NOFS BPD:Altitude 400 – 450 km, width 5 hrs LT
DMSP BPD:Altitude 840 km, width 30 latitude
[Huang et al., 2009, GRL]
Detrend C/NOFS Plasma Densities
• Variations in plasma density obscured by changing orbital altitude
• Detrend PLP densities using IRI (ver. 2007.3) as follows:
Ndet = N(PLP) * (IRI(500)/IRI(C/NOFS))
N(PLP) is the density measured by PLP along the orbit;
IRI (500) is the model value at 500 km, at the equator, at C/NOFS longitude, UT, DOY etc.;
IRI (C/NOFS) is the model value at C/NOFS location, UT, DOY etc.
• Use 1-minute averages of PLP densities• Result - densities all mapped to 500 km altitude, equator• Plots show density as function of geographic longitude
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C/NOFS Orbit 953, 19 June 2008
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Initial and Detrended C/NOFS DensitiesOrbit 953, 19 June 2008
Dayside Detrended Plasma Densities June 2008
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5 104
1 105
1.5 105
2 105
8-10LT
Ave
. Det
. Den
s
0
5 104
1 105
1.5 105
6-8LT
Ave
Det
. Den
s
5 104
1 105
1.5 105
2 105
2.5 105
0 60 120 180 240 300 360
10-12LT
Ave
Det
. Den
s
Geog. Long
1 105
1.5 105
2 105
2.5 105
3 105
12-14LT
Ave
Det
Den
s
1 105
2 105
3 105
4 105
14-16LT
Ave
Det
. Den
s
0
1 105
2 105
3 105
0 60 120 180 240 300 360
16-18LTA
ve D
et. D
ens
Geog. Long
IRI PLP
Nightside Detrended Plasma DensitiesJune 2008
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0
1 105
2 105
3 105
18-20LT
Ave
Det
. Den
s
0
1 105
2 105
3 105
20-22LT
Ave
Det
. Den
s
0
5 104
1 105
0 60 120 180 240 300 360
22-24LT
Ave
Det
. Den
s
Geog. Long
0
2 104
4 104
0-2LT
Ave
Det
Den
s0
1 104
2 104
2-4LT
Ave
. Det
. Den
s
0
2 104
4 104
6 104
0 60 120 180 240 300 360
4-6LT
Ave
Det
. Den
s
Geog. Long
IRI
PLP
Ionospheric Tidal Structures
• PLP data analyzed from May 2008 to December 2009
• Climatology of tidal structures similar to planetary wave climatology (strongest in June – August, weakest around December –January)
• Other C/NOFS experiments show similar wave-4 structures (electric fields, ion drifts, n/n)
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-30
-15
0
15
30
0 60 120 180 240 300 360Neu
tral
Den
sity
Res
idu
als
Geographic Longitude
June 2008 Plasma and Neutral Densities 20-22 LT Sector
0
5 104
1 105
Ni(
PL
P)
12
-20
-10
0
10
20
0 60 120 180 240 300 360Neu
tral
Den
sity
Res
idu
als
Geographic Longitude
5 104
1 105
1.5 105
2 105
2.5 105
N(P
LP
)
June 2008 Plasma and Neutral Densities 10-12 LT Sector
Summary
• Detrended PLP densities show tidal structures, most obvious on dayside
• Deep minimum persists on nightside around 330 (SAA)
• Climatology of plasma tides agrees with planetary wave source
• GRACE averaged neutral densities also show tidal structures
• Ion/neutral tides do not coincide!
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