COST296 WG1 Ionospheric monitoring and modelling

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COST296 WG-1 Ionospheric monitoring and
modelling

• J. Latovicka
• Institute of Atmospheric Physics, Prague, Czech
  Republic, jla_at_ufa.cas.cz.

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Leaders  J. Latovicka (CZ) and I.
Stanislawska (PL)WP1.1 Near Earth space plasma
monitoringLeader D. Altadill (ES) WP1.2 Data
ingestion and assimilation in ionospheric
modelsLeaders D. Buresova (CZ) and B. Nava (IT)
WP1.3 Near Earth space plasma modelling and
forecastingLeaders I. Kutiev (BG) and H.
Strangeways (UK)WP1.4 Climate of the upper
atmosphereLeaders J. Bremer (DE) and E. Turunen
(FIN)
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Maintaining and extending the flow of real-time
and retrospective ionospheric monitoring data to
databases.

• 10 ionosondes of the COST296 network (Chilton,
  Ebro, Tromso, Juliusruh, Dourbes, Pruhonice,
  Lycksele, El Arenosillo, Rome, and Athens)
  continue contributing with real-time VI data to
  WDC Chilton (RAL, http//www.ukssdc.ac.uk/prompt_d
  atabase.html), some to DIDBase, and DIAS
  prototype databases.
• Some stations provide also manually corrected
  data, like Ebro (http//www.obsebre.es/php/ionosfe
  ra.php (revised data)) or Pruhonice, part of them
  being available at RAL database.
• Validating the quality and consistency of
  monitoring data, particularly those collected in
  real time.

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Database of more than 40 days of GPS-derived
slant TEC data at 30 seconds time interval for
about 50 stations in Europe have been prepared.
It has to be noted that the data have been
produced using a filter on slant TEC rate of
change of 2 TEC unit per minute.
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Developing parameters describing the state of the
ionospheric plasma. The Germany and
UK teams have proposed new ionospheric activity
indices derived from automatically scaled online
data from several European ionosonde stations.
The most reliable indices are derived from foF2.
Similar indices derived from M(3000)F2 show a
markedly lower variability indicating that the
changes of hmF2 are proportionally smaller than
those estimated from the maximum electron density
in the F2-layer. By using the ionospheric
activity indices for several stations the
ionospheric disturbance level over a substantial
part of Europe (34N60N 5W40E) can now be
displayed online.
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IRI model testing The Ebro
and Czech teams tested the Local Model (LM) of
IRI parameters for a 12-years-long data set of El
Arenosillo and for year-long data sets of
Juliusruh, Chilton, Pruhonice, Athens, and
Grahamstown (33.3S) stations. The linear
regression coefficient between the
IRI2001-predicted and observed (MARP) values was
low (R2 0.3, 0.22, and 0.1 for B0, B1, and D1,
respectively). We obtained better results for B0
parameter, when the Gulyaeva option has been used
for middle and lower-middle latitude stations
(about R2 0.55). However, the use of the LM
provides significant improvement compared with
the IRI2001 predictions - 30 for all parameters
from El Arenosillo and Pruhonice, 50 for B0 and
D1 and 20 for B1 from Juliusruh, 35 for B1 and
by 50 for B0 and D1 from Athens, and about 30
for Grahamstown parameters. The analysis of IRI
model behaviour at low latitudes, using
different formulation for the topside profile,
showed a tendency to underestimate TEC, which is
stronger using NeQuick topside option. The
behaviour of the bottomside reflected in the
NeQuick topside appears as one of the causes of
the underestimations of TEC and topside electron
density.
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Comparison of the linear coefficient of
determination R2 for IRI2001 model-predicted
(red) and LM-calculated (blue) parameters B0 and
B1 for four European stations (upper and middle
panels) for 2004. Bottom panel - R2, D1, El
Arenosillo for varying solar activity.
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Various IRI-related resultsA
near real-time ionosphere electron density
retrieval technique has been elaborated and
implemented both using the IRI and the NeQuick
models. The technique is based on the model
adaptation to GPS-derived TEC data obtained from
a single ground station. Comparison with
observations - both models are able to reproduce
reasonably well foF2 experimental values, but in
some cases the NeQuick achieves better
performance in reproducing the diurnal behaviour
of foF2.The Ebro, Czech, and UMLCAR teams
investigated the behavior of the neutral scale
height Hm at hmF2 deduced from electron density
profiles N(h). The temporal behavior of Hm shows
systematic daily and yearly patterns that can
easily be fitted to diurnal and annual harmonic
functions. The spectral characteristics of the
above functions are solar activity dependent. The
model for Hm at the F2 peak can be used as the
lower limit for construction of the topside N(h)
model in terms of a vary-Chap function.
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Forecasting of foF2 and TEC

• An ionospheric forecasting empirical local model
  over Rome (IFELMOR) to predict the state of foF2
  during strong geomagnetic storms and disturbed
  ionospheric conditions has been developed as a
  part of the prediction and retrospective
  ionospheric modelling over a given area. The
  empirical storm-time ionospheric correction model
  (STORM) has been compared with IFELMOR model for
  significant geomagnetic storms (ap gt 150) from
  2000 to 2003. The results provided by IFELMOR are
  satisfactory and encourage in the development of
  other short-term forecasting empirical local
  models for a number of stations to produce a
  short- term forecasting map of foF2 over the
  European area.
• IZMIRAN accomplished a system of ionospheric
  short-term (1-24 hours in advance) foF2 forecast.
  It is completely automatic and works in real
  time. Hourly foF2 values come from Chilton,
  Juliusruh, Athens, Rome, Pruhonice and El
  Arenosillo. This prediction method provides
  better accuracy than the IRI-2000 model for
  severe ionospheric storm conditions.

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The METU-NN-C technique based on the Hammerstein
Model has been employed to forecast TEC grid
values. The overall absolute TEC error map is
plotted in Figure. The model gave accurate
forecast maps before, during and after the
disturbed conditions. The average absolute error
in 1 hour forecast mapping of the TEC values is
found to be 1.50 TECU. Compared to the METU-NN
Model this error value is about 10 smaller.
Absolute error map for observed and 1 h. ahead
forecast TEC during 16-29 Nov. 2003.
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The development of the Electron Density
Assimilative Model (EDAM)
EDAM forecasts are only likely to be effective up
to a few hours in the future.
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Investigation of ionospheric variability

• The Ebro team investigated the typical
  time/altitude variability of the ionospheric
  electron density at mid-latitudes over Europe.
  The largest variability occurs at the base of the
  F region during nighttime, mainly from sunset to
  midnight, and it shows different solar cycle and
  seasonal pattern (summer maximum) depending on
  local time. The coupling from below by wave
  activity in the MLT region is potential driver. A
  model of the expected deviations from typical
  N(h)-profiles was proposed.
• A four-class classification of TEC variability
  was introduced
• undisturbed" or quiet state with relative
  deviation of TEC lt 0.20,
• "disturbed" state with relative deviation
  between 0.20 and 0.50,
• "very disturbed" state with relative deviation
  between 0.50 and 0.80,
• "extreme or storming" state with relative
  deviation gt 0.80.
• Linear regression analyses show clearly the
  annual response of TEC to changes in solar
  activity and its dependence on latitude, whereas
  the Slab Thickness is independent of solar
  activity and of latitude gt the dependence on
  solar activity and location of TEC and Nmax is
  very similar.

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Space weather impacts on the midlatitude
ionosphere

• The UMLCAR and Ebro teams have investigated
  geomagnetic storms effects on the ionosphere. Two
  longitudinal chains at American and European
  sectors were used and it was shown that
  ionosondes provide an advantage of looking into
  the altitude distribution of the ionospheric
  reaction to the geomagnetic storms. Moreover the
  Digisonde network is a useful tool for studying
  spatial effects of the magnetic storms. A
  catalogue of the ionospheric disturbed periods
  with duration of 3h or longer is compiled for
  each station and presented at two web sites, at
  the IZMIRAN and IDCE (http//www.cbk.waw.pl/).

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The pre-storm enhancements of foF2 do not exhibit
a systematic latitudinal dependence and are not
accompanied by a corresponding change of hmF2.
They occur both day and night, and tend to appear
more often in summer half of the year. Several
potential sources of pre-storm enhancements were
excluded solar flares (occasionally can
strengthen the pre-storm enhancements), soft
particle precipitation in dayside cusp,
magnetospheric electric field penetration,
auroral region activity (AE index), and
Mikhailovs quiet-time F2-layer disturbances.
However, the origin of pre-storm enhancements
remains to be uncovered.
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Impact of atmospheric waves

• Annular solar eclipse of 3 October 2005. The
  supersonic motion of Moons cool shadow through
  the atmosphere generated gravity waves. According
  to the Ebro digisonde data analysis, the source
  region was the lower thermosphere below about 180
  km altitude (Pruhonice for eclipse of August
  1998 it was about 180-200 km). The height
  interval of gravity wave excitation does not
  differ much from heights where the solar
  terminator excites gravity waves (around 200 km).
• Planetary waves in foF2. Typical persistency from
  5 waves (T 5 days) to 3 waves (T 16 days),
  same for Europe, U.S. and Japan. Limited
  longitudinal extent of planetary wave events.
• Response of the ionospheric infrasound to strong
  meteorological tropospheric events displays
  dominance of Doppler spectra by infrasonic waves
  of periods of 3-4 min for the severe storm
  events.

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Peculiar infrasound range phenomena. S-shapes
(Figure) and oblique quasi-linear shape (QLS)
traces. S-shapes occur predominantly near sunrise
and sunset, mostly related to solar terminator.
As for QLS events, a typical QLS has a frequency
span around 10 Hz, duration of about 20 s and a
slope about 0.4-0.5 Hz/s. We excluded several
potential sources of QLSs such as aircrafts,
satellites, bolides, meteors, meteorites,
thunderstorms, or geomagnetic storms.
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Long-term trends
Summary of consistent mesospheric, thermospheric
and ionospheric trends, which form the global
pattern/scenario
There are still large discrepancies as for trends
in foF2 and hmF2. Trends in foF2 are rather of
geomagnetic origin but weak and they can affect
to some extent only long-term predictions and
planning.
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Conclusions

• COST296 WG-1 deals mainly with the bottomside
  ionosphere but partly also with TEC and topside
  electron density profile. We can provide for IRI
  community
• Data including electron density profiles and
  ionospheric parameters derived from manually
  checked ionograms.
• Results of IRI model testing.
• Results of development of other models including
  NeQuick and various prediction models.
• Results of investigations of some interesting
  phenomena in the ionosphere.
• There is some personal overlap between WG-1 and
  IRI community.