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Author: search.filters.author.Rungraengwajiake, SarawootSubject: search.filters.subject.ionosphere

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    Ionospheric delay gradient monitoring for GBAS by GPS stations near Suvarnabhumi airport, Thailand
    (2015-10-01)
    Rungraengwajiake, Sarawoot
    ;
    Supnithi, Pornchai
    ;
    Saito, Susumu
    ;
    Siansawasdi, Nattapong
    ;
    Saekow, Apitep
    Ground-based augmentation system (GBAS) is an important augmentation system that provides the differential corrections and integrity information from the reference stations to the aircrafts for precision approach and landing. It is known that the nonuniform ionospheric characteristics called "ionospheric delay gradient" can cause the errors in differential corrections degrading the accuracy and safety level if they are undetected by the reference stations. Since the characteristics of the ionosphere are different for each region, the ionospheric delay gradient observations in equatorial and low-latitude regions are necessary for developing the suitable ionospheric threat models. The purpose of this work is to analyze the ionospheric delay gradients observed by three GPS stations near Suvarnabhumi airport in Bangkok, Thailand, which is located in the low-latitude region. The ionospheric irregularities in this region are mainly caused by the plasma bubble, which usually occurs after sunset. The GPS data with plasma bubble occurrence during the September equinox 2011 and 2012 are therefore analyzed. In addition, the data analysis procedure utilizing the rate of total electron content change index for this region is proposed. The results show that the ionospheric delay gradients observed in the west-east direction appear higher than the south-north direction, varying from 28 to 178 mm/km during plasma bubble occurrences.
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    Drift velocity estimation of ionospheric disturbance using GPS observations
    (2014-01-01)
    Bumrungkit, Acharaporn
    ;
    Rungraengwajiake, Sarawoot
    ;
    Supnithi, Pornchai
    ;
    Siansawasdi, Nattapong
    The Ground-Based Augmentation System (GBAS) based on the global positioning system (GPS) is used for positioning accuracy improvement of the aircraft landing. However, the ionospheric irregularity can cause irregular electron density that affects the accuracy of GBAS system. In this work, we analyze the drift velocity of ionospheric irregularity or plasma bubble phenomenon by using the correlation time of slant total electron content (STEC) from two GPS receivers that are located near Suvarnabhumi airport, Thailand. The data on September 1<sup>st</sup>, 2011 with the plasma bubble occurrence is analyzed. The result shows the drift velocity of plasma bubbles is about 108 meterspersecond (m/s). © 2014 IEEE.