Characterization of low frequency variations due to space weather conditions at low latitude region / Siti Noor Aisyah Ahmad

The process of interaction between space weather conditions and Earth's magnetic field is one of the factors that lead to the variation effect of both ultra-low frequency (ULF) and very low frequency (VLF) waves which can be observed in space and on the ground. These variations are recorded in the frequency range of ULF and VLF with 1.7 - 500 mHz and 3- 30 kHz respectively. Study on both ULF and VLF at low latitude region is still not well established, due to the lack of understanding in ULF and VLF. Therefore, this study investigates the characteristics of both ULF and VLF due to space electromagnetic perturbations at low latitude region. In the first part of this study, solar wind (SW) parameters were analyzed during a maximum solar cycle of 24. Solar wind (SW) parameters that considered in this analysis are solar wind speed, Vsw (km/s), solar wind input energy,e (ergs/s) and solar wind dynamic pressure, Pdyn (nPa). The observation period covers on year 2012 (for ULF) and 2013 (for VLF). In the second part, the recorded ULF magnetic pulsations are extracted from Magnetic Data Acquisition System (MAGDAS) magnetometer was observed at low latitude stations; Langkawi (LKW), Malaysia and Tirunelveli (TIR), India. In the third part, VLF data were investigated from Atmospheric Weather Electromagnetic System for Observation Modeling and Education (AWESOME) VLF receiver located at Universiti Kebangsaan Malaysia (UKM), Malaysia, which received the signals from Katabonunan (VTX), India and Lualuaiei (NPM), USA. The results of analysis show that Pc5 ULF pulsations have a positive correlation with the SW parameters. While for VLF variation, the result shows weak correlation with the SW parameters. To connect the solar wind with ULF and VLF variations, there are some possibilities that vary on both variations. The main source which effects on the Pc5 ULF pulsation is from coronal mass ejection (CME) and coronal hole (CH) which can produce high-speed solar wind (HSSW) traveling to the Earth. Both CME and CH influenced the variations of the Earth's magnetic field at all latitudes. However, for VLF, the variation is directly not affected by SW parameter due to ionospheric absorption at D-layer of ionosphere.