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Author: search.filters.author.Boonchuk, T.

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    Comparison between foF2 observations and IRI-2001 model predictions at Thailand equatorial latitude station
    (2008-10-06)
    Wichaipanich, N.
    ;
    Boonchuk, T.
    ;
    Leelaruji, N.
    ;
    Hemmakorn, N.
    ;
    Supnithi, P.
    In this paper, the comparison between the F2-layer critical frequency (foF2) observations and international Reference Ionospheric (IRI) model predictions is presented. The data used for this study are obtained from bottomside ionogram recorded by the FM/CW ionosonde at Chumphon campus of King Mongkut's Institute of Technology Ladkrabang (latitude 10.72°N and longitude 99.37°E), Thailand, located near the magnetic equator. The measurement data coverage from January to December of a low solar activity year (2006) is analyzed based on the diurnal, seasonal variation and then compared with IRI-2001 model predictions. Generally, the foF2 obtained from the IRI (URSI and CCIR) model closely follows observed foF2 values. Comparing the results of URSI and CCIR options for foF2, we find that for low solar activity, both the URSI and CCIR options of the IRI model give foF2 values close to the ones measured at Chumphon, but the CCIR results produce smaller range of deviation than the URSI results. All comparative studies give feedback for new improvements of CCIR and URSI IRI models. ©2008 IEEE.
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    Low latitude ionosphere-thermosphere dynamics studies with inosonde chain in Southeast Asia
    (2007-01-01)
    Maruyama, T.
    ;
    Kawamura, M.
    ;
    Saito, S.
    ;
    Nozaki, K.
    ;
    Kato, H.
    An ionosonde network consisting of a meridional chain and an equatorial pair was established in the Southeast Asian area. Three of four ionosondes are along the magnetic meridian of 100° E; two are close to the magnetic conjugate points in Northern Thailand and West Sumatra, Indonesia, and the other is near the magnetic equator in the Malay Peninsula, Thailand. The fourth ionosonde is also near the magnetic equator in Vietnam but separated by about 6.3° towards east from the meridional chain. For a preliminary data analysis, nighttime ionospheric height variations at the three stations of the meridional chain were examined. The results demonstrate that the coordination of the network has a great potential for studying ionosphere/thermosphere dynamics. Through the assistance of model calculations, thermospheric neutral winds were inferred and compared with the HWM93 empirical thermospheric wind model. Higher-order wind variations that are not represented in the empirical model were found.
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    Rain attenuation of satellite link in Ku-band at Bangkok
    (2005-12-01)
    Boonchuk, T.
    ;
    Hemmakorn, N.
    ;
    Supnithi, P.
    ;
    Iida, M.
    ;
    Tanaka, K.
    Rain attenuation is a major factor to degrade the system performance in a frequency above 10 GHz. This paper presents a statistical analysis of the rainfall rate and the rain attenuation data on satellite to ground propagation path. By measuring 12.7-GHz beacon signal attenuation from JCSAT satellite and the rainfall rate continuously. Yearly cumulative distribution functions were then compared to predicted models. The Crane Global model for the rain zone H provides overestimated predicted values to the measured ones. For the rain zone G, the Crane Global model provides close values to ITU-R model; both are smaller than the measured ones. © 2005 IEEE.