Sains Malaysiana 46(10)(2017): 1987–1995

http://dx.doi.org/10.17576/jsm-2017-4610-38

 

Variasi Jumlah Kandungan Elektron Ionosfera di Malaysia ketika Solar Minimum

(Variations Total Electron Content of Ionospheric in Malaysia during Mininum Solar)

 

SITI AMINAH BAHARI^1*, MARDINA ABDULLAH¹ & BAHARUDIN YATIM²

 

¹Space Science Center, Institute of Climate Change, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

²Pusat Pengajian Fizik, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

Diserahkan: 8 Mac 2017/Diterima: 20 September 2017

 

 

ABSTRAK

 

Ionosfera merupakan satu lapisan atmosfera bumi yang mengandungi elektron bebas dan boleh memberi kesan ralat kepada perambatan gelombang elektromagnetik terutama kepada sistem kedudukan global (GPS). Kesan jumlah kandungan elektron(TEC) dan fenomena melibatkan sistem suria-magnetosfera-ionosfera-termosfera kepada isyarat satelit dan komunikasi radio sentiasa berubah. Kajian ini memfokuskan kepada perubahan TEC ketika aktiviti suria di tahap minimum. Objektif utama kajian ini adalah untuk mengkaji variasi TEC di rantau Malaysia terhadap masa harian, perubahan musim, aktiviti suria dan medan magnet bumi. Isyarat GPS yang disebarkan pada dua frekuensi jalur L1 dan L2 mengandungi data kod dan fasa membolehkan pengiraan TEC diperoleh menggunakan GPS. Data GPS pada tahun 2007 yang diperoleh daripada Jabatan Ukur dan Pemetaan Malaysia (JUPEM), digunakan dalam kajian ini. Hasil kajian di Asia Tenggara menunjukkan ketika musim ekuinoks, nilai purata TEC dicatatkan tinggi iaitu 35 TEC unit (TECU) berbanding dengan nilai purata TEC pada soltis yang mencatatkan bacaan 25 TECU. Aktiviti suria didapati lebih memberi kesan kepada perubahan TEC berbanding dengan medan magnet bumi dengan faktor kolerasi antara aktiviti suria adalah lebih tinggi iaitu 0.64 berbanding dengan medan magnet bumi iaitu 0.34 sahaja. Kajian ini tertumpu ketika aktiviti suria di tahap minimum dengan keadaan medan magnet bumi secara puratanya adalah senyap. Ini seterusnya membolehkan hasil kajian ini menjadi asas kepada maklumat mengenai ionosfera di Malaysia.

 

Kata kunci: GPS; ionosfera; solar minimum

 

ABSTRACT

The ionosphere is a layer in the Earth’s atmosphere where free electrons exist in sufficient numbers to affect the propagation of electromagnetic waves especially the Global Positioning System (GPS) signals. The ionosphere is also known as ‘space weather laboratory’ as it is directly affected by any activity in space. The influence of the total electron content (TEC) and physical phenomenon regarding the sun-magnetosphere-ionosphere-thermosphere system on satellite and radio communication is constantly changing. The study of the TEC variation in ionosphere and structures is important to ensure the security of radio communication systems, to enhance the currently restricted global ionospheric mapping and accurate space weather forecasting. This paper focused on the variation of TEC during solar minimum. The main objective of this research was to study the variation of TEC over Malaysia on diurnal, seasonal solar and geomagnetic activity using GPS. Since the GPS signals are broadcasted in two widely spread L-band frequency channels L1 and L2 consisting of code and phase, it is possible to determine the TEC using GPS. To achieve this objective, GPS data for year 2007 was obtained from the Department of Survey and Mapping Malaysia (JUPEM) were used in this research. The results over South East Asia showed that the mean TEC during equinox was higher than solstice, whereby 35 TECU was recorded during the equinoxes but only 25 TECU was observed during solstice. It was found that solar variation had more effects on the variation of TEC as compared to the geomagnetic variation. The correlation factor for solar variation was higher, that is 0.64 but yielded only 0.34 for geomagnetic variation. This research was carried out during solar minimum and quiet geomagnetic conditions. Therefore, the results from this research can be used as a reference for the characterization of ionosphere in Malaysia.

 

Keywords: GPS; ionosphere; minimum solar

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*Pengarang untuk surat-menyurat; email: sitiaminahbahari@ukm.edu.my