Xiao Wang, Jiankui Shi, Guojun Wang, Yu Gong

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Comparison of ionospheric F2 peak parameters foF2
and hmF2 with IRI2001 at Hainan
Center for Space Science and Applied
Research Chinese Academy of Sciences

• Xiao Wang, Jiankui Shi, Guojun Wang, Yu Gong
• Email wangx_at_cssar.ac.cn
• or
  xwang_at_spaceweather.ac.cn
• State Key Laboratory of Space Weather, CSSAR
• Chinese Academy of Sciences

IRI/COST 296 Workshop
2007.07.13, Prague
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Outline

• Introduction
• Data and Method
• Results
• foF2
• hmF2
• Summary

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1. Introduction

• The International Reference Ionosphere (IRI) is a
  widely used empirical model of the ionosphere.
  Since its first release in 1978, updates and
  improvements to this model have been made. In the
  updated version IRI2001, many new changes have
  been made to this model.
• The IRI model uses either CCIR or URSI
  coefficients to predict the foF2 and hmF2 based
  on the 12-month running average sunspot number.
• The ionospheric data from Chinese continent were
  not used when producing the those coefficients.
  The ionosphere in China region is affected
  greatly by the low latitude ionosphere which is
  very complicated. A validation study of the model
  compared with observational results in China is
  necessary.
• The ionospheric parameters from Hainan, China
  (19.5N, 109.1E) are used to validate the IRI2001
  in the low latitude.

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2. Data and method

• Data
• Ionospheric parameters (foF2, hmF2, M(3000)) (Kp
  lt3)
• Instrument DPS-4
• Location Hainan, China
• (109.1oE,19.5o N Geomag
  178.950 E,8.10 N)
• Period Feb 2002 Mar 2007
• Time interval 15 minutes

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Method
In this study, behaviors of the observed foF2 and
hmF2 are investigated and compared with IRI
predictions. For the observation data, monthly
median /average values of foF2, and hmF2
parameters with quarter-hourly time interval for
diurnal variation, seasonal variation and solar
cycle. For the IRI2001, monthly median /average
values of quarter-hourly foF2 and hmF2 parameters
of IRI prediction with CCIR, URSI coefficients or
M3000 observation as model input.
Delta foF2 foF2OBS- foF2IRI Delta
hmF2 hmF2OBS- hmF2IRI
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Results
a. foF2
foF2 observation
foF2 prediction (URSI)

• Diurnal/ seasonal variation, solar cycle
• Time and duration of foF2 peak and night peak
• Short period of low values at sunrise

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• Variation pattern
• Systematical deviation between observation and
  prediction
• Overestimate Morning time and night in winter
• Underestimate Other time

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• Variation pattern
• Systematical deviation between observation and
  prediction
• Overestimate Morning time and night in winter
• Underestimate Other time

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• Variation pattern
• Systematical deviation between observation and
  prediction
• Overestimate Morning time and night in winter
• Underestimate Other time

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• Variation pattern
• Systematical deviation between observation and
  prediction
• Overestimate Morning time and night in winter
• Underestimate Other time

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• Variation pattern
• Systematical deviation between observation and
  prediction
• Overestimate Morning time and nighttime in
  winter Underestimate Other time
• Solar Cycle big deviation at high and moderate
  solar activity small deviation at solar min.
• Lower value period at 7 oclock for Obs. foF2 in
  winter and equinox

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Deviation of foF2 between observation and IRI
prediction (CCIR)

• Obvious systematical difference in the whole
  period
• Overestimated and underestimated time period for
  LT
• Seasonal variation underestimated equinox (big)
  for ( 0200LT, 1300LT and 2000LT), winter
  (smallest)
• Overestimated winter (biggest)
  summer(smallest)
• Smallest difference about 0600LT and
  1000-1100LT
• Solar Cycle
• a. value
• b. duration

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Deviation of foF2 between observation and IRI
prediction (URSI)
Similar with CCIR except for smaller
deviation. Overestimate foF2 is more obvious.
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b. hmF2
hmF2 Observation
hmF2 prediction (CCIR)

• Diurnal/ seasonal variation, solar cycle
• Peak time 1315 LT for Obs. 1300LT for CCIR
• Peak at sunrise always for Obs. Only in winter
  for CCIR

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• Variation pattern
• Systematical deviation between observation and
  prediction
• overestimate Morning time and 0300LT for equinox
• underestimate Other time
• Good agreement for the IRI hmF2 with observed
  M(3000) input

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• Variation pattern
• Systematical deviation between observation and
  prediction
• overestimate Morning time and 0300LT for equinox
• underestimate Other time
• Good agreement for the IRI hmF2 with observed
  M(3000) input

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• Variation pattern
• Systematical deviation between observation and
  prediction
• overestimate Morning time and 0300LT for equinox
• underestimate Other time
• Good agreement for the IRI hmF2 with observed
  M(3000) input

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• Variation pattern
• Systematical deviation between observation and
  prediction
• overestimate Morning time and 0300LT for equinox
• underestimate Other time
• Good agreement for the IRI hmF2 with observed
  M(3000) input

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• Variation pattern
• Systematical deviation between observation and
  prediction
• overestimate Morning time and 0300LT for equinox
• underestimate Other time
• Good agreement for the IRI hmF2 with observed
  M(3000) input

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Deviation of hmF2 between observation and IRI
prediction (CCIR)

• Obvious systematical difference in the whole
  period
• Overestimated and underestimated time period for
  LT
• Seasonal variation Underestimated equinox (big)
  for ( 0200LT and 2000LT), winter (smallest)
• Overestimated winter (biggest)
  summer(smallest)

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Deviation of hmF2 between observation and IRI
prediction (observed M(3000))
Good agreement with observation except for
a. overestimated in the daytime and
underestimated in the nighttime in solar max.
b. Slightly overestimated in the daytime and
underestimated at sunrise
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4. Summary

• Comparison of the low-latitude ionospheric
  F2 peak parameters foF2 and hmF2 with IRI2001
  were done using the ionospheric parameters
  obtained with DPS-4 digisond in Hainan
  observatory from 2002 to 2007, which was
  characterized by a wide range of solar activity,
  from solar maximum (2002) to solar minimum
  (2007). Some results can be got
• For the foF2
• Generally IRI predictions follow well the
  diurnal, seasonal variation and solar cycle
  patterns of the experimental values of foF2. The
  occurring time of foF2 peak of observations is
  earlier and it also can last longer time.
• There are systematical deviation between
  experimental values and IRI predictions with
  either CCIR or URSI coefficients. Generally IRI
  model underestimates the values of foF2 from
  about noon to sunrise of next day, especially in
  the period of 1700-2200LT, and slightly
  overestimates them from about 0600LT to about
  1100LT and also about noon in winter.
• The positive deviation is strongest in equinox
  and weak in winter. The negative deviation is
  strongest in winter and weak in summer.

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• It seems that there are bigger deviations between
  IRI Model predictions and experimental
  observations for the solar median.
• There are better agreement between observation
  and IRI with URSI coefficients.
• For the hmF2
• Generally the IRI predicted hmF2 values using
  CCIR M(3000)F2 option shows a poor agreement with
  the experimental results, but there is a
  relatively good agreement in summer.
• There are systematical deviation between hmF2ccir
  and hmF2obs. The IRI overestimate hmF2 from
  0700LT to 1200LT and about 0300LT and
  underestimate it at sunrise and from noon to
  sunset. The deviations of sunrise and afternoon
  decrease with solar activity decreasing, but the
  deviation in the morning increases.
• The deviation at sunrise and from noon to sunset
  is bigger in equinox.
• When using the measured M(3000)F2 as input, the
  agreement between the IRI predicted hmF2 values
  with the measured M(3000)F2 and the experimental
  hmF2 is very well except that IRI overestimates
  slightly hmF2 in the daytime and underestimates
  it in the nighttime.

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Thanks