The utilization of ionospheric data from
African observatories: the future
Sandro M. Radicella
Head, Telecommunications/ICT for development,
Abdus Salam ICTP
Trieste, Italy
Expert Meeting on
Improving Space Weather Forecasting in the Next Decade
10 - 11 February 2014
VIC, Vienna, Austria
Ionospheric weather
• Ionospheric weather is an important element of Space
Weather.
• Its forecast depends on data availability and knowledge of
physical processes involved.
• The ionosphere at the low latitudes affected by the so called
“Ionospheric Equatorial Anomaly” (IEA) shows the highest
variability and irregular behaviour indicating the existence of
a very active and complex “weather” in that region of the
globe.
• Most of the African continent ionosphere is affected by the
IEA.
Ionospheric regions
Ionospheric regions (a simplified view)
Ionosphere over Africa (“climatic” NmF2)
Ionospheric Research Issues for SBAS,
SBAS Ionospheric Working Group, 2003
Arrows indicate the limits of
continental Africa.
Nava et al. 2001
Variability of TEC
Variability of TEC at mid latitudes
GPS derived vertical TEC at 5 min interval for
Roquetes
(Lat. 40.8º, Lon. 0.5º E, Mag. Dip 57º), October
2000.
Variability of TEC at low latitudes
GPS derived vertical TEC at 5 min interval
for Libreville
(Lat. 0.4º N, Long. 9.7º E, Mag. Dip –25º),
October 2000.
However
How competing influences
from above and below
control ionospheric weather,
particularly over Africa?
http://icon.ssl.berkeley.edu/science/
Ionosphere-troposphere
coupling (1)
• Most of the ionospheric variability is attributed to geomagnetic activity.
• But, scientific literature since the early 80’ of last century indicates that
coupling with tropospheric processes can play an important role in such
variability.
• Potential effects of convective complexes and intense tropospheric storms
have been indicated as possible origin of waves and tides in the F-region
of the ionosphere that influences its variability (Emanuel and Sanders,
1983; Manzano et al, 1998; Martinis and Manzano, 1999; P. Sauli and J.
Boska, 2001, Bishop et al, 2006)
• The last 8 years have shown an increased interest about this topic
including the possible effects of non-migrating tides of tropospheric origin
as an explanation of the longitudinal variations of the IEA development,
and the effects of the ENSO on the low latitude ionosphere. (Immel et al,
2006; Pedatella and Forbes, 2009)
Ionosphere-troposphere
coupling (2)
• In particular 2011-2013 published papers have shown lower atmosphereionosphere model results that indicate that at low latitudes a substantial
percentage of the electron density variability can be of tropospheric origin
including the effect of ENSO. (Jin et al, 2011, Pedatella and Liu, 2013, Liu et
al, 2013)
• The effect of non-migrating tides has been shown also in TEC behaviour
over South America using model calculations (Nogueira et al, 2013)
Ionosphere-troposphere
coupling (3)
Liu et al, 2013,
indicate that The dayto-day ionosphere
variability in the model
is primarily caused by
the perturbations
originated in lower
atmosphere, since the
model simulation is
under constant solar
minimum and low
geomagnetic
conditions.
Ionosphere-troposphere coupling
(4)
Pedatella and Liu, 2013,
show that the ENSO
introduces inter-annual
variability of 10–15% in
the ionosphere. The
ENSO should therefore
be considered as a
potentially significant
source of variability in
the Earth’s upper
atmosphere.
The state of the art at present
• It appears evident now that ionospheric weather at low
latitudes cannot be attributed only to solar and geomagnetic
activity but is also linked to the troposphere.
• Model simulation results are giving solid clues about the way
tropospheric activity affects ionospheric weather.
• However, more experimental evidences are required to be
able to reach an adequate forecasting capacity particularly in
regions like the African continent.
• The quantitative estimates of both solar-geomagnetic activity
and forcing from below are needed to allow a sound forecast
of ionospheric weather.
The present situation
in Africa (1)
• A recent Competence Survey under the ESA ALCANTARA Initiative
“Ionospheric ground based monitoring network in low-latitude regions:
Africa” done by ICTP with the collaboration of Profs. B. Rabiu (NASDA,
Nigeria) and O. Obrou (University of Cocody, Cote d’Ivoire) have allowed to
see the present status of ionospheric observations and research in Africa
in general and at low latitudes in particular.
From the survey it appears evident
that now-days the number of GNSS
receivers able to provide
ionospheric information allows to
start systematic research of the
type needed for ionospheric
weather assessment.
The present situation
in Africa (2)
• Ionosondes able to provide direct information about
the height profile of the electron density are needed to
complete such research. At the moment only three
ionosondes are operating or will operate in the near
future in the African equatorial region.
• Magnetometers from several projects are installed in
key locations in low latitudes and can contribute
efficiently to the research on ionospheric weather.
• The use of satellite in-situ ionospheric information
together with ground based observations would
contribute substantially to assess ionospheric weather.
The present situation
in Africa (3)
• If the investigation is combined with adequate
tropospheric activity studies, a sound forecast of
ionospheric weather could be achieved.
• A key point is that research on ionospheric
weather at low latitudes in African has to be
made with the substantial contribution from
African scientists to guarantee a sustainable
effort for several years to come.
• The present situation of ionospheric research
done in Africa indicates that this is possible.
Ionospheric research in Africa
• The ALCANTARA
Survey provided very
interesting results
about ionospheric
research by African
scientists working in
the continent.
• Data about the
growing number of
papers published in
peer-review journals
by these scientists are
encouraging.
Examples of recent ionospheric
research in Africa (1)
Inospheric variability
(ionospheric weather):
Solar Eclipse effect over
Ilorin, Nigeria
Adeniyi et al, 2009
Examples of recent ionospheric
research in Africa (2)
Inospheric variability
(ionospheric weather):
TEC variability over
Ilorin, Nigeria
Bolaji et al 2012
The contribution from the
international community (1)
• It has to be noted that most of the instruments operating in the
African low latitudes have been provided by national or
international institutions, projects or program like AMBER,
MAGDAS, SHINDA, Boston College, Stanford University, Kyoto
University and ICTP.
• Training of African scientists have benefited by the efforts of
African Universities like Rhodes University of South Africa, Ilorin
University in Nigeria, Bahir Dar University in Ethiopia, University
of Cocody in Cote d’Ivoire.
The contribution from the
international community (2)
• An important contribution to the training of African scientists
was done by the "Groupe International de Recherche en
Géophysique Europe Afrique" (GIRGEA) organized by Dr.
Christine Amory-Mazaudier of the Laboratory of Plasma Physics
of the French CNRS.
• Another contribution in the same direction came through the
Partnership between Boston College and ICTP towards the
establishment of African research groups in the area of GNSS
science and technology with a strong emphasis on ionospheric
research using GNSS receivers.
In summary (1)
• I concentrated my attention to the problem of assessing the
relative contribution of solar-geomagnetic and tropospheric
effects on ionospheric weather at low latitudes to obtain its
forecasting.
• This subject should become an important topic for future studies
towards Space Weather Forecasting in general and Ionospheric
Weather Forecasting in particular.
• African data, particularly from the low latitudes region of the
continent, are essential for such work.
In summary (2)
• At present exists a basic network of observatories in Africa able to
get ionospheric information or related type of data.
• There is an increasing number of scientists doing ionospheric
research in the continent.
• African scientists should be able to participate in these studies in
collaboration with researchers from other regions of the world.
• It has to be remember that Ionospheric Weather forecasting is of
key importance not only for its intrinsic scientific value but also
for telecommunications and satellite navigation applications.
References (1)
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T. J. Immel, E. Sagawa, S. L. England, S. B. Henderson, M. E. Hagan, S. B. Mende, H.
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electron density and TEC with profile data from topside ionograms”, Advances in
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