Post on 23-Apr-2018
Boston College Seminar Series • Dec 1, 2016
Earth’s Ionosphere Groundbased Measurements
and Real-time Ionospheric Modeling
Bodo Reinisch1,2 and the Lowell GIRO Data Center Team
1Lowell Digisonde International, LLC 2University of Massachusetts Lowell
Boston College Seminar Series • Dec 1, 2016
Acknowledgement
The Lowell Team UML - LDI
Boston College Seminar Series • Dec 1, 2016
Outline
• Ionosonde observations of the ionosphere
• International Reference Ionosphere -- IRI
• IRI-based Real Time Assimilating Mapping-- IRTAM
• Bottomside Traveling Ionospheric Disturbances -- TIDs
Boston College Seminar Series • Dec 1, 2016
Earth’s Ionosphere & Space Weather
Boston College Seminar Series • Dec 1, 2016
Magnetotail
MAGNETOSPHERE
Atmosphere / Ionosphere
IMAGE S/C
Solar Wind-Magnetosphere Interaction
Boston College Seminar Series • Dec 1, 2016
Boston College Seminar Series • Dec 1, 2016
Electron Density Distribution
Ionosphere and Plasmasphere
IRI EDP and Parameters Plasmasphere EDP
7
Boston College Seminar Series • Dec 1, 2016 8
Measuring the Bottomside Electron Density Profile
O-wave reflections of HF waves
At the reflection point:
O-wave is perp to Bg, and fN = f
X-wave is parallel to Bg (not shown here)
Boston College Seminar Series • Dec 1, 2016
9
Digisonde Ionogram Autoscaling real-time Electron Density Profile
𝑓𝑁[𝐻𝑧] ≅ 9 𝑁[𝑚−3]
Digisonde: Reinisch et al., 2009 NHPC profile: Reinisch und Huang, 1983 ARTIST: Galkin et al., 2009
Boston College Seminar Series • Dec 1, 2016 10
Comparing Digisonde NHPC profiles with incoherent scatter radar measurements
Several thousand inverted profiles from Digisonde ionograms at Millstone Hill and Arecibo were compared with the profiles derived from co-located incoherent scatter radar measurements for half a solar cycle from 1990-1996 [Chen, et al., 1993].
Comparison summary:
1. The height differences in the F layer are in the average less than 5 km
2. The valley model is very good in general, but during twilight or ionosphere storms larger deviations occur.
Boston College Seminar Series • Dec 1, 2016
Eglin 01 FEB 2012 Isodensity contours
0300 0245 0145
200 km
300 km
0315
1015
0730
Complicated ionogram signatures in the presence of Medium- and Large- Scale TIDs
ARTIST ionogram scaler is capable of extracting vertical echo traces and calculate the vertical EDP
Boston College Seminar Series • Dec 1, 2016
Ionogram during disturbed conditions
Eglin, FL
22:15 LT
Boston College Seminar Series • Dec 1, 2016 13 From the IRI2015 Workshop, Bangkok
Phase and Group Velocities in a Magnetoplasma
In a dispersive medium, the phase and group velocities differ. The phase velocity is (neglecting collisions)
𝑣𝑝ℎ =𝑐
𝜇. Since m<1 in a plasma, vph > c
The group velocity in a dispersive medium is 𝑣𝑔 =𝑑𝜔
𝑑𝑘
The group refractive index is
𝜇′ =𝑐
𝑣𝑔= 𝑐
𝑑𝑘
𝑑𝜔=
𝑑
𝑑𝜔𝜇𝜔 = μ + 𝜔
𝑑𝜇
𝑑𝜔
Neglecting the magnetic field and collisions (Y=0 and Z=0), 𝜇 = 1 − 𝑓𝑁 𝑓 2 . Then
𝜇′ =𝑑
𝑑𝑓𝜇𝑓 =
1
𝜇 𝑜𝑟
𝜇𝜇′ = 1
𝑣𝑔𝑣𝑝ℎ = 𝑐2 Therefore 𝑣𝑔 < 𝑐
Note that vg →0 at the reflection point where 𝜇 = 0. Important: Directions of vph and vg are different when using the plane wave description (as is usually done)! Huang and Reinisch [2012] showed that using spherical wave solutions makes vph ӏӏ vg . Huang, X. and B. Reinisch (2012), Excited spherical waves in unbounded cold magneto-plasma and applications in radio sounding, Radio Sci., 47, RS0L08, doi:10.1029/2011RS004940.
Boston College Seminar Series • Dec 1, 2016 14 IRI2015 Workshop
Appleton-Lassen Formula for the Index of Refraction
The indices of refraction 𝑛±are given by the Appleton-Lassen* formula:
with 𝑘 =𝜔
𝑣=
𝜔 𝑛
𝑐
𝑛±2 = 1 −
𝑋
1 − 𝑖𝑍 −𝑌𝑇2
2 1 − 𝑋 − 𝑖𝑍±
𝑌𝑇4
4 1 − 𝑋 − 𝑖𝑍 2 + 𝑌𝐿2
𝑋 = 𝑓𝑁2 𝑓2 ; 𝑌 = 𝑓𝐵 𝑓; 𝑍 = 𝜈 2𝜋𝑓 where
𝑓𝑁2 =
𝑒2
4𝜋𝜀0𝑚𝑁 ≅ 80.6 𝑁 (𝑁 𝑖𝑛 𝑚−3, 𝑓𝑁 𝑖𝑛 𝐻𝑧)
𝑓𝐵 =𝑒𝐵𝑔
2𝜋 𝑚≅ 1.4 𝑀𝐻𝑧
*often called “Appleton-Hartree” formula, but Hartree (1931) had included an incorrect dielectric polarization term. Lassen had derived the correct 𝒏± in 1927.
Boston College Seminar Series • Dec 1, 2016
15
Digisonde Ionogram Autoscaling real-time Electron Density Profile
𝑓𝑁[𝐻𝑧] ≅ 9 𝑁[𝑚−3]
Digisonde: Reinisch et al., 2009 NHPC profile: Reinisch und Huang, 1983 ARTIST: Galkin et al., 2008
Boston College Seminar Series • Dec 1, 2016 16
Off-vertical Echo Traces and Severe Spread F
Boston College Seminar Series • Dec 1, 2016
Groundbased Ionosondes -- Digisonde Data Products
• 1931: First ionogram
• 1936: 5 ionosondes in the world
• 1957: 150 ionosondes in the world
• 1969: First Lowell Digisonde built
• 2016: <a few hundred?> ionosondes ever built • 231 ionosonde locations registered in SPIDR (1942…
current)
• 164 Lowell Digisondes (1969 …. current)
4º 8º
0°
90° 270°
180°
Boston College Seminar Series • Dec 1, 2016
Digisonde History
Digisonde 128 (1969)
Digisonde 256 (1978)
DPS4 (1993)
DPS4D (2006)
Boston College Seminar Series • Dec 1, 2016
Global Ionosphere Radio Observatory (GIRO) Lowell GIRO Data Center
[Reinisch and Galkin, 2011]
Boston College Seminar Series • Dec 1, 2016
24-hour GIRO ionogram movies
Boulder C.Paulista Dourbes El Arenosillo Ebro Eglin AFB
Gakona Hermanus Irkutsk Jicamarca Jeju Is. Kwajalein Is.
RRL-Chilton Millstone Hill Moscow Norlisk Pt. Arguello Pruhonice
http://giro.uml.edu/IonogramMovies/
Boston College Seminar Series • Dec 1, 2016
http://ionosphere.meteo.be
Ionospheric plasma density specifications in real time
Stankov et al. (2011): Local ionospheric electron density profile reconstruction in real time. Adv. Space Res. 47(7), 1172-1180.
Boston College Seminar Series • Dec 1, 2016
HAARP Heating Experiments
f1< f2 f3> f2
f2 (heater)
Ionograms show the bottomside of expanding plasma ball appearing as an artificial ionization layer
Credits: Todd Pedersen and HAARP/AFRL team
Boston College Seminar Series • Dec 1, 2016
HAARP Heating Campaign 2008 Digisonde Skymap and Waterfall Display
Topside of the expanding
plasma structure ~50 km wide,
accelerating upward
along the magnetic field line
at 80-100 m/s
Boston College Seminar Series • Dec 1, 2016
EDP from Ionospheric Radio Occultation
24
[Jakowski et al., 2007]
Comparison with ISR
Boston College Seminar Series • Dec 1, 2016
COSMIC and Digisonde concurrent measurements
Corresponding Ionogram Profiles obtained by COSMIC and DPS4D Digisonde
25
[From Baiqi Ning, 2014]
0.2 0.4 0.6 0.8 10
100
200
300
400
500
600
700
800
900
Year=2011 DOY=344 UT(C)=23.77 UT(I)=23.75
Density (106/cm3)
Heig
ht
(km
)
Iono
Cos
Boston College Seminar Series • Dec 1, 2016
IRI-based Real Time Assimilative Mapping -- IRTAM The new IRTAM-2016
26
• Digisonde GIRO network sends measured ionogram data in real time to LGDC for assimilation into the IRI maps for fof2, hmF2, B0, B1
[Galkin et al., 2012]
Boston College Seminar Series • Dec 1, 2016 27
IRI and IRTAM-2016 Anchor points:
– NmF2, hmF2
– NmF1, hmF1
– NmE, hmE
– B0, B1, D1
Time expansion in IRI
EDP all measured by GIRO Digisondes
0 02( ; , ; , ) ( , ; , ) ( , ; , )
6( , ; , )cos ( , ; , )sin
1
G G M M G G M M G G M M
i G G M M i i G G M M i
foF t a b t
a t b t
i
IRTAM-2016 assimilates the measured foF2, hmF2, B0, and B1 values
IRI
IRTAM uses same expansion to represent the measured data between t-24h and t, and finds new coefficients 𝑎𝑖
′, 𝑏𝑖′.
Similarly for hmF2, B0 and B1
Boston College Seminar Series • Dec 1, 2016
B0
foF2
hmF2
3D global bottomside ionosphere in real-time
Real-Time IRI
Real-time
PORT STANLEY
obs
Diurnal fit to GIRO data
4D data assimilation: 24-hour fit of minimizing differences between IRI and GIRO
x 52 GIRO stations
Port Stanley data courtesy of Sarah James, RAL UK
Global Spatial fit
Jones-Gallet Gk basis (76), CCIR = total map coefficients: 1064 [24-hour global weather]
NmF2, hmF2, B0, B1 anchors
IRI p
rofi
le f
orm
alis
m
15 minute cadence
Low confidence autoscaling
Boston College Seminar Series • Dec 1, 2016
In Combination with VTEC:
29
Total Electron Content Peak Density Peak Density Height Slab Thickness
Deviation from expected quiet-time behavior Red: larger than model Blue: smaller than model
Boston College Seminar Series • Dec 1, 2016
Test Period: 2013.02.19 to 2013.06.11
IRTAM foF2 = typical x2 improvement
Green sites: loss of quality < 40%
Cntl Site Included vs excluded Lost Q
BC840 2.20 vs 1.75 20 %
IF843 1.92 vs 1.39 28 %
WP937 2.14 vs 1.46 32 %
AU930 2.10 vs 1.34 36 %
EG931 2.00 vs 1.28 36 %
foF2 Improvement factor Comparisons with control site included vs excluded
Real-Time IRI Improvement over Climatology Average improvement ~ factor of 2 in terms of <Obs-Model> error reduction (15 million comparisons)
Boston College Seminar Series • Dec 1, 2016
Not all GIRO sites are equally important
Test Period: 2013.02.19 to 2013.06.11
Cntl Site Included vs excluded Lost Q
MHJ45 2.11 vs 1.24 41 %
PA836 2.61 vs 1.29 51 %
PRJ18 2.86 vs 1.05 63 %
No improvement to IRI climatology when PRJ18 is excluded
foF2 improvement factor Comparisons with control site included vs excluded
Red sites: loss of quality > 40%
Boston College Seminar Series • Dec 1, 2016
Testing IRTAM-2016 Performance foF2 prediction for Austin
IRI
IRTAM including Austin data
IRTAM excluding Austin data Neighboring GIRO sites adequately
steer the foF2 prediction for Austin
Boston College Seminar Series • Dec 1, 2016
Digisonde Tilt and TID Measurements
Vertical incidence and oblique sounding
Electron Density Profiles
Ionospheric Tilt
D2D TID Measurements
4º 8º
0°
90° 270°
180°
Boston College Seminar Series • Dec 1, 2016
Digisonde Tilt Measurements
• Overhead skymap shows locations of echo sources:
– pi, the virtual range (1/2 ToF·c)
qi, the zenith angle, and
fi, the azimuth angle (counted from the north to the east).
• Vector to “cluster” center specifies tilt:
q0 is the zenith angle of the normal to the isodensity contour, and f0 the azimuth angle of the normal
4º
8º
90° 270°
180°
(pi, qi, fi) (p0, q0, f0)
tilted ionosphere
[Huang and Reinisch, 2006]
Skymap
Boston College Seminar Series • Dec 1, 2016
TID Measurements
+ + =
OUTPUT: Period, Phase, Amplitude, and velocity vector of TID
FREQUENCY-ANGLE-SOUNDING (FAS) TECHNIQUE
[Paznukhov et al., ASR, 2012]
D2D Skymap
Boston College Seminar Series • Dec 1, 2016
Net-TIDE Europe https://sites.google.com/site/spsionosphere/
Boston College Seminar Series • Dec 1, 2016
Digisonde-to-Digisonde (D2D) sounding detects TIDs (measurements from the NetTIDE Project were used1)
Dourbes → Juliusruh, 778 km
D2D Skymap
NATO D2D NetTIDE Project
Juliusruh, April 6, 2015; 3450 kHz
1Technique developed under AFRL SBIR project RETID, 2016
Boston College Seminar Series • Dec 1, 2016
Simulating Raytracing and Mirror Reflection for TID
We assume that during the passage of a TID the electron density ( , , , )N h t at height h, time
t, and location ( , ) can be represented by
0( , , , ) ( , , , ) 1 cos ( )IRTAMN h t N h t A t D
The phase distance D depends on the azimuth of the direction of the TID propagation. The
angular frequency of the TID wave is related to its period T, and the wave number to the
wavelength : Ω = 2𝜋 𝑇, 𝐾 = 2 .
Raytracing Amplitude: density variation @ constant height
Mirror Reflection
[Huang et al., 2016, Radio Sci.]
Doppler frequency vs time
Amplitude: height variation
Azimuth vs time Elevation vs time
Boston College Seminar Series • Dec 1, 2016
TID Detection and Evaluation
Boston College Seminar Series • Dec 1, 2016
D2D Signal and TIDs: Modeling
05:00 05:10 05:20 05:30 05:40
-0.2
-0.1
0.0
0.1
0.2
Oct 15, 2013; foF2=5.5 MHz
TID (model2, A=2.7%,az=180,=300km,T=20min)
Dist = 601 km; 5 MHz
Do
pp
ler,
Hz
05:00 05:10 05:20 05:30 05:40
39
40
41
42
43
44
45
46
(at Tx)
Ele
va
tio
n, d
eg
05:00 05:10 05:20 05:30 05:40
840
850
860
870
880
O-mode
X-mode
Gro
up
pa
th, km
UT
05:00 05:10 05:20 05:30 05:40
-0.2
-0.1
0.0
0.1
0.2
Oct 15, 2013; foF2=5.5 MHz
TID (model2, A=2.7%,az=180,=300km,T=20min)
Dist = 601 km; 5 MHz
Do
pp
ler,
Hz
05:00 05:10 05:20 05:30 05:40
39
40
41
42
43
44
45
46
(at Tx)
Ele
va
tio
n, d
eg
05:00 05:10 05:20 05:30 05:40
840
850
860
870
880
O-mode
X-mode
Gro
up
pa
th, km
UT
14% 3% 3%
Boston College Seminar Series • Dec 1, 2016
D2D Signal and TIDs: First results D2D sounding: Dourbes-to-Roquetes
Time Amplitude,
%
Wavelength, km
Azimuth, ⁰
Period, min
Velocity, m/s
01:13:40 11.0 810 167 80 169
01:18:40 11.3 852 168 80 178
01:23:40 11.5 955 168 80 199
01:28:40 11.4 1133 167 80 236
01:33:40 10.5 1253 168 80 261
01:38:40 9.8 1436 177 80 299
01:43:40 9.9 1732 188 80 361
01:48:40 9.9 1684 196 80 351
01:53:40 9.6 1535 197 80 320
01:58:40 9.1 1442 193 80 300
02:03:40 8.3 1472 194 80 307
02:08:40 7.1 1593 208 80 332
FAS Computations
Large-scale TID propagating southward [from auroral region]
Boston College Seminar Series • Dec 1, 2016
References
• Chen, C. F., B.W. Reinisch, J.L. Scali, X. Huang, R.R. Gamache, M.J. Buonsanto, and B.D. Ward, The accuracy of ionogram-derived N(h) profiles, Adv. Space Res., 14, 43 - 46, 1994.
• Galkin, I.A., G.M. Khmyrov, A.V. Kozlov, B.W. Reinisch, X. Huang, and V.V. Paznukhov (2008), The ARTIST 5, in Radio Sounding and Plasma Physics, AIP Conf. Proc. 974, 150-159 doi:10.1063/1.2885024.
• Galkin, I.A., B.W. Reinisch, X. Huang, and D. Bilitza (2012), Assimilation of GIRO Data into a Real-Time IRI, Radio Sci., 47, RS0L07, doi:10.1029/2011RS004952.
• Huang, X. and B. W. Reinisch, Real time HF raytracing through a tilted ionosphere, Radio Sci., 41(5), RS5S47, 10.1029/2005RS003378, 2006.
• Huang, X., B. W. Reinisch, G. S. Sales, V. V. Paznukhov, and I. A. Galkin (2016), Comparing TID simulations using 3-D ray tracing and mirror reflection, Radio Sci., 51, 337–343, doi:10.1002/2015RS005872.
• ITU-R, International Telecommunications Union (2009), ITU-R reference ionospheric characteristics, Recommendation P.1239-2 (10/2009). Retrieved from http://www.itu.int/rec/R-REC-P.1239/en on November 29, 2011.
• Jones, W. and R. Gallet (1962), Representation of Diurnal and Geographic Variations of Ionospheric Data by Numerical Methods, J. Res., NBS 66D, No. 4, 419-438.
• Paznukhov, V. V., V. G. Galushko, A. S. Kascheev, and B. W. Reinisch (2012), Digisonde observations of AGWs/TIDs with Frequency and Angular Sounding Technique, Adv. Space. Res., 49(4), 700-710, doi:10.1016/j.asr.2011.11.012.
• Rawer, K. and D. Bilitza, International Reference Ionosphere - plasma densities: status 1988, Adv. Space Res. 10, #8, 5 - 14, 1990.
• Reinisch, B. W. and X. Huang, Automatic Calculation of electron density profiles from digital ionograms, 3, Processing of bottomside ionograms, Radio Sci., 18, 477-492, 1983.
• Reinisch, B.W. and I.A. Galkin (2011), Global Ionospheric Radio Observatory (GIRO), Earth Planets Space, vol. 63 no. 4 pp. 377-381, doi:10.5047/eps.2011.03.001.