Dieter Bilitza

1
International Reference Ionosphere and the
Polar Ionosphere
Dieter Bilitza GSFC, Code 672, Greenbelt,
Maryland and George Mason University, Virginia

• Introduction and Current Status
• Polar Ionosphere
• Auroral Characteristics from TIMED/GUVI
• IRI-2007 and some Applications

2
INTERNATIONAL REFERENCE IONOSPHERE (IRI) Terms
of Reference

• The IRI Working Group was established to develop
  and improve a reference model for the most
  important plasma parameters in the Earth
  ionosphere.
• IRI is a joint project of COSPAR and URSI.
• COSPARs (Committee on Space Research) prime
  interest is in a general description of the
  ionosphere as part of the terrestrial environment
  for the evaluation of environmental effects on
  spacecraft and experiments in space.
• URSIs (International Union of Radioscience)
  prime interest is in the electron density part of
  IRI for defining the background ionosphere for
  radiowave propagation studies and applications.
• The model should be primarily based on
  experimental evidence using all available ground
  and space data sources and should not depend on
  the evolving theoretical understanding of
  ionospheric processes. But theoretical
  considerations can help to find the appropriate
  mathematical functions, to bridge data gaps and
  for internal consistency checks.
• As new data become available and as older data
  sources are fully evaluated and exploited, the
  model should be revised in accordance with these
  new results.
• Where discrepancies exist between different data
  sources the IRI team should facilitate critical
  discussions to determine the reliability of the
  different data bases and to establish guidelines
  on which data should be used for ionospheric
  modeling.

3
P. Bradley, M. Rycroft, Lj. Cander (U.K.), K.
Rawer, W. Singer (Germany), A. Alcayde, R.
Hanbaba (France), B. Zolesi, S. Radicella
(Italy), M. Friedrich (Austria), E. Kopp
(Switzerland), D. Altadill (Spain)
L. Triskova, V. Truhlik (Czech Rep) I. Kutiev
(Bulgaria) I. Stanislawska (Poland), S. Kouris
(Greece)
A. Danilov V. K. Depuev T. Gulyaeva G.
Ivanov-Kholodny K. Ratovsky A. Mikhailov
B. Reinisch D. Bilitza T. Fuller-Rowell K. Bibl
X. Huang J. Sojka D. Anderson V. Wickwar L.
Scherliess M. Codrescu S-R Zhang C. Mertens
K. Oyama K. Igarashi S. Watanabe
W. Weixang M.-L. Zhang
S.-Y. Su
Kyoung Min
S. Pulinets
M. Abdu
K. Mahajan S.P. Gupta P.K. Bhuyan
P. Wilkinson P. Dyson B. Ward
O. Obrou
R. Ezquer M. Mosert de Gonzalez
A. Poole, L.-A. McKinnell
J. Adeniyi
IRI Working Group Members
4
Paris, France
2004
C4.2 Advances in Specifying Plasma Temperatures
and Ion Composition in the Ionosphere
Volume 37 Issue 5 2006
2005
Ebro, Spain
New Satellite and Ground Data for IRI and
Comparisons with Regional Models
Volume 39 Issue 5 2007
C4.2 - Solar activity variations of ionospheric
parameters.
2006
In press
New Data for Improved IRI TEC representation
Oct 16-20
2007
IRI/COST Workshop Ionosphere Modeling, Forcing
and Telecommunications,
In pre-paration
Prague, Czech Republic
COSPAR GA, Montreal, Canada, July 13-20 C4.2 -
Updating IRI with ground and space data
2008
URSI GA, Chicago, August 9-16 G02 Density
Profiling and Models
5
International Reference Ionosphere Monthly
averages in the altitude range 50-1500 km
Electron density Electron temperature Ion
composition (O, O2, NO, Cluster, N, He,
H) charge neutrality Ne ?ni Ion
temperature Ion drift (currently only
equatorial vertical F-region drift) spread-F
occurrence probability (currently limited to
South-American sector)
6
Data Sources Instrument Platform Used
for Comments Ionosondes Worldwide
Ne from E Fifties to
Network to F2
now Incoherent Jicamarca, Ne profile
Few radars, Scatter Arecibo, (E-
valley) many Radar St. Santin,
Te, Ti parameters
MillstoneH.,
Malvern,
Topside Alouette
1, 2 Ne topside newer data Sounder
ISIS 1, 2 profile from
Ohzora,
ISS-b, IK-19 Insitu
AE-C,-D,-E Ne topside many more
Aeros-A,-B profile,Te,Ti, DMSP, OGO
IK-24, DE-2 ion comp. Hinotori Rocket
data Ne D-region, sparse
compilations Ion comp.
data set
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Build-up of IRI electron density profile
Mathematical functions Global Variations
Spherical harmonics, special
functions Time Variations Fourier,
simple sin/cos, step-functions Height
Variations Epstein functions
Normalized to E and F peaks
Global models for foF2/NmF2, foF1/NmF1,
foE/NmE hmF2/M(3000)F2, hmF1 , hmE
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Ionosonde stations represented on NGDC CD-ROM
Digisonde stations
9
Middle and Low Latitudes Good data foundation
Well tested and evaluated Good description of
variations with height, latitude, longitude,
local time/solar zenith angle, season/month,
solar and magnetic activity Now considered the
standard (ISO and ECSS).
High Latitudes (auroral, polar) Sparse data
record Only few modeling efforts Need to
consider dependence on IMF and magnetospheric
magnetic field Highly variable Modeling needs
to include representation of many special
features, like troughs, ovals, holes, crests
(density/temperature enhancements and
depletions) IRI provides background ionosphere
based on few high-latitude ionosondes Modeling
of auroral and polar ionosphere
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Auroral and Polar Ionosphere The solar wind,
consisting mainly of protons and electrons moving
at ultra-sonic speeds of 400 - 800 km/s (more
than a million miles per hour). The solar
wind pressure strongly compresses the Earths
magnetosphere on the dayside and draws it out
into an extremely long tail on the nightside.
Electrons out of the solar wind are able to
diffuse into magnetospheric tail and form a
reservoir called the plasma sheet. The
magnetosphere and the solar wind form an enormous
electrical dynamo including one component which
carries electrons down magnetic field lines where
eventually they collide with the atmospheric gas
causing it to glow. On the dayside solar wind
particles have direct access to the Earth's
atmosphere via the cusp regions.
Cusp
Cusp
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Oval latitudes span Fairbanks, Alaska, Oslo,
Norway, and the Northwest Territories.
A glowing band loops around the southern polar
region in the distance as viewed by astronauts
onboard the space shuttle.
Polar VIS
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Each oval consists of a band of auroral glow
within which are embedded visible auroral arcs,
bands and other shapes. The two auroral ovals
pivot around the earth's geomagnetic poles,
located near Thule, Greenland and Vostok,
Antarctica. They are displaced somewhat toward
the nightside of the earth with the consequence
being that the ovals extend to lower latitude at
night than they do in daytime. When conditions in
the solar wind blowing out from the sun to the
earth are quiet, the auroral ovals contract
poleward and become quite narrow. During active
conditions the ovals enlarge in diameter and
widen. On rare occasions the northern oval may
expand to reach southern California likewise,
the southern oval will expand toward the equator,
simultaneously.
Kp4
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Rotkaehl et al., 2007
14
(No Transcript)
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IRI - Data Comparisons
16
Mosert, Prague 2007 Antarctic ionosonde at San
Martín (68.1S 293.0E geographic
53 S magnetic),
1996 (Rz9.1)
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Belgrano (77.9S, 321.4E geographic 67.5
magnetic),
2000 (Rz 117)
Figure 13
18
Friedrich and Fankhauser, Prague, 2007 EISCAT
Svalbard, 78N, L 15.5 300,000 profiles,
1997-03-11 to 2003-09-26
local model
EISCAT Data
NmF2
IRI
hmF2
midnight
noon
? IRI-foF2, extrapolated to 79N, is not sensible
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IRI - 2007
20
Model for Ne in auroral lower ionosphere
McKinnell and Friedrich, Adv. Space Res.,
37(5), 2006
? NeuralNet model trained with 700,000
EISCAT radar data points and 115 rocket profiles
? NN input space local magnetic time (LMT),
total absorption (Li), local magnetic index
(K), solar zenith angle, F10.7 cm solar radio
flux, pressure surface (p) (season, altitude)
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Year 2002, Day 182, Hr 23.93 UT, ZA 87
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Year 1984, Day 332, Hr 3.42 UT, ZA 117
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IRI New Developments
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Inclusion of Auroral Boundaries in
IRI Authors Instrument Parameterization Image
data Feldstein and Starkov 1967 IGY All
sky imager Q 0, 1, 2, 3, 4, 5, 6 Holzworth and
Meng 1975 Mathematical representation of
Feldstein-ovals in MLT, CGM, Q Carbary
2005 Polar UVI MLT, CGM, Kp Zhang and Paxton
2007 TIMED/GUVI MLT, CGM, Kp (energy flux, mean
energy) Particle data Energy flux and mean
energy Wallis and Budzinski 1981 ISIS-2 MLT,
InvLat, quiet and active Spiro, Reiff, Maher
1982 AE-C, -D MLT, InvLat, 4 levels of mag
activity (AE) Hardy, Gussenhoven et al.
1987 DMSP MLT, CGM, 7 levels
(Kp) Fuller-Rowell and Evans 1987 NOAA/TIROS
MLT, MagLat, Hemispheric power input PEM-2004
(see Cai et al. 2007) FAST, EISCAT MLT, ILAT,
AE Electric field data High-latitude
convection pattern Heelis, Lowell, Spiro
1982 AE-C, -D ion drift data MLT, only for Bz
southward Heppner and Maynard 1987 OGO-6,
DE-2 MLT, CGM, IMF-Bz, Kp Rich and Maynard
1989 One of the agreements among these models
is that soft electrons are dominant in the cusp
region around magnetic midday.
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Energy flux
Mean energy
Maps of estimated electron energy flux (a) and
mean energy (b) using GUVI data for orbit 00900
on February 6, 2002. The grid size is 30x30 km.
The red and green lines with arrows are for the
tracks of TIMED and DMSP F14. The tip of the
arrow indicate the location of TIMED and DMSP F14
at 124327 UT. (c) and (d) Comparison between
results from GUVI and DMSP F14 along the DMSP F14
track. The two blue vertical lines indicate the
region where the DMSP F14 electron energy flux is
above 1.0 erg/(cm2-s).
26
GUVI auroral models based on four years
(2002-2005) of data and organized by magnetic
latitude (Mlat), magnetic local time (MLT), and
Kp (0-10).
Modeled electron energy flux (left panels) and
mean energy (right panels) at four Kp values 1,
3,5 and 7. The white circles are for magnetic
latitudes. The red lines are for the equatorward
and poleward boundaries of the oval at a fixed
flux 0.25 ergs/(cm2 s). The yellow numbers are
magnetic local time.
27
Nightside auroral boundaries (equatorward black
line, poleward red line) and nightside peak
electron flux location (green line) versus Kp.
28


Left panel DMSP F16 SSUSI auroral image over
Greenland. The white bar over intense aurora
(indicated by a solid red arrow) shows scan track
of the Sondrestrom Incoherent Scatter Radar.
Right NmE, hmE along the white bar deduced from
SSUSI UV measurements (blue line) and the radar
NmE, hmE (red line).
29

Global map of IRI peak E-region electron density
NmE for July 2004 at 1400 UTC Solomon, 2006.
Contribution from precepetating electrons at high
latitudes not yet included.
30
Krankowski et al., 2007 GPS-deduced trough
location Dependence on geomagnetic activity
December 1999
31
IRI Future Plans for High Latitudes

• Inclusion of Auroral Characteristics
• - Auroral Boundaries
• - Auroral NmE and hmE models including
• contribution from precipitating electrons
• - Representation of mid-latitude trough
• Electron temperature enhancement
• Effort would benefit from input of Barrow GPS and
  ionosonde data.

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THANK YOU
33
IMAZ model for auroral Lower Ionosphere
New models for topside electron density
IRI-2007
New model for topside ion composition
Equatorial disturbance ion drift model
Spread-F occurrence probability model (Brazilian
sector)
Akebono model for electron temperature in
plasmasphere
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Fig. 9. Ionization production rate caused by
precipitating electrons with energies ranging
from 100 to 1000 eV. (From Millward et al., 1999).
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Applications and Usage
36
Rios et al., JASTP, 2007, Tucuman Digisonde, Near
Crest of Equatorial Anomaly
foF2 / MHz
hmF2 / km
LT /hour
LT /hour

• - - IRI/URSI
• Ionosonde

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Chau and Woodman JGR, Dec 2005
Friedrich et al. GRL, April 2006
140
120
Altitude/km
100
80
Jicamarca measurements
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Rocket (NASA EQUIS-II), 20 Sep 2004, near ALTAIR
radar on Kwajalein Atoll (9N, 187E), 1130 LST,
SZA19.7, Apogee 131.2 km, F10.7
101. Comparison of Ne from nosetip probe, wave
propagation experiment, ALTAIR, and the models
IRI and FIRI.
First Jicamarca D and E region density measure-
ments (13 Dec 2004, 11 LT) and comparison with
IRI.
38
Comparison with KOMPSAT Kim et al., JASTP, 2006
Comparison of KOMPSAT-1 Te measure- ments in the
low-latitude nighttime at 685 km with the two IRI
Te options. Newer option (Intercosmos) shows
better agreement.
Te-Intercosmos
Te-ISIS, Aeros
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STANDARD FOR ENGINEERING APPLICATIONS

• IRI is used as the standard in Natural Orbital
  Environment Definition Guidelines for Use in
  Aerospace Vehicle Development NASA Tech Memo.,
  NASA-TM-4527, 1994.
• IRI is the standard ionospheric model in
  System Engineering Space Environment handbook
  of the European Cooperation for Space
  Standardization ECSS, 1997.
• IRI was recognized as the international
  standard for the ionosphere in an official
  Commission G Resolution during the 1999
  International Union of Radio Science (URSI)
  General Assembly.
• IRI is recommended by the International
  Telecommunication Union (ITU) for the computation
  of retardation effects on radio waves traveling
  through the ionosphere.
• IRI is the ionospheric model proposed in TS
  16457 of the International Standardization
  Organization (ISO).

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VISUALIZATION AND ONLINE TOOLS FOR SPACE
ENVIRONMENT PARAMETERS

• Current time global NmF2, hmF2, and TEC IRI
  maps (S.-R. Zhang, MIT) http//madrigal.haystac
  k.mit.edu/models/IRI/index.html
• Real-time maps of IRI TEC for Australiasia,
  North America, Europe, and Japan (IPS, Sydney,
  Australia) http//www.ips.gov.au/Satellite/2/1
• Computation of ionospheric conductivities using
  IRI and CIRA (WDC Kyoto, Japan)
  http//swdcwww.kugi.kyoto-u.ac.jp/ionocond/index.h
  tml
• MPEG movies of global maps of IRI density and
  temperature at the Space Environments Branch of
  NASA Glenn Research Center
• http//powerweb.grc.nasa.gov/pvsee/info/movies/iri
  90.html
• The SPace ENVironment Information System
  (SPENVIS) developed at the Belgian Institute for
  Space Aeronomy for ESA/ESTEChttp//www.spenvis.om
  a.be/spenvis/
• IRIWeb for online computation and plotting of
  IRI parameters developed at NASA/GSFC NSSDC/SPDF
• http//modelweb.gsfc.nasa.gov/models/iri.html
• 3-d electron density visualization using AVS
  (CRL, Tokyo, Japan )

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foF2 UT 0 - 24
foF2 LT 0 - 24
hmF2 UT 0 - 24
log(Ne) UT 0 - 24
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BACKGROUND IONOSPHERE FOR EVALUATING DATA
RETRIEVAL TECHNIQUES

• Testing algorithms that convert GPS
  measurements into global TEC
• maps (Hernandez-Pajares et al., 2002)
• TEC from NNSS Doppler measurements (Ciraolo and
  Spalla, 2002)
• Reliability of tomographic methods (Bust et
  al., 2004).
• Testing algorithm for GPS/MET occultation
  measurements (Tsai et al.,
• JASTP, submitted Hocke and Igarashi, 2002)
• Developing data analysis algorithm for
  retrieval of electron densities
• from TIMED/GUVI airglow measurements (DeMajistre
  et al., 2004)

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IONOSPHERIC CORRECTIONS FOR SINGLE-FREQUENCY
ALTIMETRY

• Pathfinder Project Longtime data record of sea
  surface heights updating IRI with ionosonde data
  (Bilitza, Bhardwaj and Koblinsky, 1997
  Lillibridge and Cheney, 1997)
• ERS Quick-look data (ERS Products User Manual,
  1996)
• Work with Geosat Follow On (GFO) data (Zhao et
  al., 2002.

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IONOSPHERIC PARAMETERS FOR THEORETICAL MODELS

• Comprehensive Ring Current Model (CRCM)
• Ebihara, et al., 2004, 2005
• Ionospheric Conductances for Rice Convection
• Model (RCM) DeZeeuw et al. 2004
• Baseline against which the predictive skills of
• physics-based models are compared
• Siscoe et al., 2004

45
IRI Usage Statistics
JGR/GRL/RS/JSTP/AG papers using IRI
2005 51 2006 54
IRI ftp site downloads
5,000/month IRIweb online accesses
4,000/month
Dec06 6,058 Nov06 4,772
Apr07 4,470 May074,241