Sains Malaysiana 47(8)(2018): 1923–1929

http://dx.doi.org/10.17576/jsm-2018-4708-34

 

Perubahan Sistem Arus Ionosfera di Kawasan Asia Tenggara semasa Ribut Geomagnet pada Fasa Suria Minimum

(Changes in Ionospheric Currents System at Southeast Asia Region during Geomagnetic Storm in Solar's Minimum Phase)

 

NURUL SHAZANA ABDUL HAMID1*, VIKSUTHORN AI WEN1, NUR IZZATI MOHD ROSLI1 & AKIMASA YOSHIKAWA2,3

 

1Pusat Pengajian Fizik Gunaan, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

2Department of Earth and Planetary Sciences, Faculty of Sciences, 33 Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan

 

3International Center for Space Weather Science and Education (ICSWSE), Kyushu University 53

6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan

 

Diserahkan: 3 Ogos 2017/Diterima: 19 Mac 2018

 

 

ABSTRAK

Sistem arus di ionosfera khatulistiwa terdiri daripada elektrojet khatulistiwa (EEJ) dan suria senyap (Sq). Arus EEJ merupakan satu jalur arus yang mengalir ke arah timur sepanjang kawasan dip khatulistiwa. Arus Sq pula adalah gegelung arus yang mengalir di hemisfera utara dan selatan bumi pada arah yang bertentangan. Kajian ini bertujuan untuk menganalisis kesan aktiviti matahari terhadap profil latitud sistem arus, khususnya di kawasan Asia Tenggara. Data yang digunakan dalam kajian ini merangkumi data geomagnet daripada lima stesen magnetometer dalam rangkaian MAGDAS iaitu stesen Muntinlupa (MUT), Cebu (CEB), Davao (DAV), Manado (MND) dan Pare Pare (PRP). Keamatan arus EEJ yang paling tinggi adalah pada waktu tengah hari sekitar 1000 dan 1100 LT semasa solar minimum dan kajian ini telah menganalisis sistem arus daripada 1000 hingga 1400 LT. Analisis menunjukkan bahawa ribut geomagnet yang berlaku pada 23 April 2008 adalah disebabkan oleh letusan jirim korona (CME) yang memberikan peningkatan kepada nilai arus pada hari tersebut. Peningkatan yang ketara dapat dilihat pada arus di stesen hemisfera selatan, iaitu stesen MND dan PRP. Berdasarkan analisis yang dilakukan, ia turut mendapati bahawa ribut geomagnet memberikan peningkatan kepada nilai arus walaupun di luar waktu puncak. Selain itu, profil arus ini turut dibandingkan dengan profil arus pada hari senyap iaitu pada 21 April 2008.

 

Kata kunci: Aktiviti matahari; EEJ; sistem arus ionosfera; Sq

 

ABSTRACT

Equatorial ionospheric current system consists of equatorial electrojet (EEJ) and solar quiet (Sq). EEJ current is a ribbon of current flowing eastwards along the dip equator region. On the other hand, Sq current is a loop of current that flows at the Earth’s northern and southern hemispheres in different directions. This study is focusing on analysing the effects of a solar event on the latitudinal profile of the current system, specifically in Southeast Asian region. Data used in this study are geomagnetic data from five magnetometer stations in MAGDAS network which are Muntinlupa (MUT), Cebu (CEB), Davao (DAV), Manado (MND) and Pare Pare (PRP). The EEJ current intensity is known to be highest around noon time between 1000 and 1100 LT during solar minimum and thus this study analyses the current system from 1000 to 1400 LT. The analysis showed that the geomagnetic storm occurred on 23 April 2008, which is caused by coronal mass ejection (CME), gives rises to the currents on that day. This increment is clearly observed on the currents at the southern hemisphere stations, which are MND and PRP. Our analysis also found that this geomagnetic storm gives increment to the current at the non-peak time. Apart from that, the current profile on this day is compared with the current profile from a quiet day on 21 April 2008.

 

Keywords: EEJ; ionospheric current system; solar event; Sq

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*Pengarang untuk surat-menyurat; email: shazana.ukm@gmail.com

 

 

 

 

 

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