Karakteristik Equatorial Plasma Bubbles (EPB) dari Pengamatan Radar Atmosfer Equator (EAR)

Abstract

Fenomena-fenomena seperti Equatorial Plasma Bubbles/ Equatorial Spread F (EPB/ESF) dan Equatorial Ionization Anomaly (EIA) sangat berpotensi terjadi di wilayah atmosfer atas Indonesia (ionosfer) yang terletak dalam zona aktif gangguan lapisan ionosfer, yaitu dalam rentang + 15 lintang geomagnet. Fenomena-fenomena tersebut akan mengganggu beroperasinya sistem komunikasi radio maupun satelit berupa adanya gangguan dalam amplitudo maupun fase dari gelombang radio yang diterima penerima di bumi, dikenal dengan istilah sintilasi.
Dalam penelitian ini dibahas beberapa karakteristik penting yang teramati oleh sistem Equatorial Atmosphere Radar yang telah dioperasikan di Kototabang (0,20S, 100,32E; 10,36S dip lat). Sistem antenna Radar disusun sedemikian sehingga mampu mengamati gangguan lapisan ionosfer yang terjadi tegak lurus terhadap garis-garis medan magnet, teramati sebagai Field Aligned Irregularities (FAI). Berdasarkan hasil pengolahan data diperoleh dua macam gelembung plasma yaitu post-sunset dan post-midnight yang keduanya dikendalikan
oleh mekanisme fisis yang berbeda. Variasi musiman kejadian kedua jenis ketidakteraturan plasma tersebut juga ditampilkan dalam makalah ini. Bulan-bulan equinox (Maret-April atau September-Oktober) adalah bulan-bulan dimana post-sunset FAI terjadi lebih sering dibanding post-midnight. Sementara bulan-bulan solstice (Desember-Januari atau Juni-Juli) adalah bulan-bulan dimana post-midnight FAI lebih sering terjadi. Gambaran tentang arah penjalaran memberikan pemahaman baru tentang bagaimana perkembangan ketidakteraturan yang
terjadi waktu ke waktu, baik secara horizontal maupun vertikal. Hasilnya memberi gambaran lebih baik tentang mekanisme kejadian EPB/ESF yang sangat bermanfaat dalam pengembangan model ketidakstabilan plasma, serta untuk melengkapi hasil pengamatan peralatan lain yang sudah ada.

Abstract

Phenomena such as Equatorial Plasma Bubbles/Equatorial Spread F (EPB/ ESF) and the Equatorial Ionization Anomaly (EIA) was potentially occured in the Indonesian region of the upper atmosphere (ionosphere) located in the active zone ionosphere disturbances, that is in the range of + 15 latitude geomagnetic. These phenomena would disrupt the operation of radio and satellite communications systems in the form of a disturbance in the amplitude and phase of the received radio wave receivers on Earth, known as scintillation. In this study addressed several important characteristics observed by the Equatorial Atmosphere Radar system that has operated in Kototabang (0.20S, 100.32E; 10.36S dip lat). Radar antenna system is arranged so that is able to observe the ionosphere interference that occurs perpendicular to the magnetic field lines, is observed as a Field Aligned irregularities (FAI). From EAR data analysis obtained two types of plasma bubbles post-sunset and post-midnight
which is driven by two kinds of different physical mechanisms. Seasonal variation of both plasma irregularities are discussed in this paper. In equinox months (March-April or September-October), post-sunset are frequently occurred rather than post-midnight. While in solstice months (December-January or June-July) post-midnight are frequently occurred. The propagation direction provide more detail explanation related to development of irregularities time by time horizontally and vertically. The results not only suggested the better understandings of mechanism of EPB/ESF occurrence, but also contributed on development of plasma instability model and
supported observations by other instrument which have already operated.