King Mongkut’s Institute of Technology Ladkrabang

E layer critical frequency over an
equatorial location in Thailand
Prasert Kenpankho a , Pornchai Supnithi a , Takuya Tsugawa b , Mamoru Ishii ba King Mongkut’s Institute of Technology Ladkrabang, Thailandb National Institute of Information and Communications Technology, JapanThe 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

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King Mongkut’s Institute of Technology Ladkrabang• Introduction• Methodology• Results• Summary2

The 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

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Introduction

foE is an important ionosphericparameter which directly affects theradio wave propagation through theionosphere. It changes dramaticallywith the time of the day, month,season and variation in solar activity.

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Solar activities
Sunspot number

F10.7 centimeter4

The 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

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International Reference Ionosphere
The objectiveof this research isas a part ofworking towards
improving the IRI
over magnetic
equatorial region5

The 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

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Methodology• Observation• IRI Model6

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Ionospheric Chumphon station

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Ionospheric Chumphon station

Chumphon station

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Ionosonde

Ionospheric measurement

Source: “The variation of critical frequency of E layer over the magnetic equatorial region, Chumphon,Thailand.” by Wongcharoen et al., 2013, IRI2013 Workshop, Poland.

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Parameters on ionogram10

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IRI 2012 MODEL

www.irimodel.org
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Results• foE variation• foE comparison• Percentage of errors

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King Mongkut’s Institute of Technology LadkrabangfoE variation

Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer criticalfrequency over the Thai station Chumphon with IRI, Advances in Space Research xxx (2015) xxx–xxx.
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King Mongkut’s Institute of Technology LadkrabangfoE comparison

Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer criticalfrequency over the Thai station Chumphon with IRI, Advances in Space Research xxx (2015) xxx–xxx.
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The 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

King Mongkut’s Institute of Technology LadkrabangfoE comparison

Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer criticalfrequency over the Thai station Chumphon with IRI, Advances in Space Research xxx (2015) xxx–xxx.
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The 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

King Mongkut’s Institute of Technology LadkrabangfoE comparison

Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer criticalfrequency over the Thai station Chumphon with IRI, Advances in Space Research xxx (2015) xxx–xxx.
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The 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

King Mongkut’s Institute of Technology LadkrabangfoE comparison

Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer criticalfrequency over the Thai station Chumphon with IRI, Advances in Space Research xxx (2015) xxx–xxx.
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The 3rd AOSWA Workshop, March 2-5, 2015, Fukuoka, Japan

King Mongkut’s Institute of Technology Ladkrabang! ( foEIRI − foEobs ) "%E = %& ×100
foEobs'((%)

Percentage of errors

Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer critical frequency over the Thai station Chumphon with IRI,
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Advances in Space Research xxx (2015) xxx–xxx.
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Root mean square error (RMSE)

Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer criticalfrequency over the Thai station Chumphon with IRI, Advances in Space Research xxx (2015) xxx–xxx.
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Summary• The foE at equatorial ionosphere over Chumphon region increases
with the increase in solar activity and declines as sun begins tomoves towards dusk.
• The foE reaches its maximum during local noon and decreases
towards sunrise and sunset for all the seasons.
• For a declining phase of the solar cycle (2005-2008), IRI predicts
the Chumphon foE measurements quite well, closely following thediurnal variation of the data.
• The largest foE differences are found during sunrise and sunset
indicating that IRI may not accurately represent the actual sunrise
and sunset times. Since IRI is an average model, the sunrise andsunset times are also averages over the season and altitude range.
Wongcharoen, P., Kenpankho, P., Supnithi, P., Ishii, M., and Tsugawa, T., Comparison of E layer criticalfrequency over the Thai station Chumphon with IRI, Advances in Space Research xxx (2015) xxx–xxx.
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We look forward to working with all of you!

THANK YOU VERY MUCH
FOR YOUR ATTENTION.
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