Invited Speaker

Dr. Antonia Savcheva

Coronal sigmoids, generally observed in X-rays and EUV, are S-shaped loops in the cores of active regions that have been shown to possess high probability for eruption. They present a direct evidence of the existence of flux ropes in the corona prior to the impulsive phase of eruptions. In order to gain insight into their eruptive behavior and how they get destabilized we need to know their 3D magnetic field structure. First, we review some recent observations and modeling, including the latest state-of-the art data-constrained and data-driven MHD simulations, of sigmoidal active regions. As the primary hosts of solar eruptions, they can also be used as useful laboratories for studying these phenomena. Then, we concentrate on the analysis of observations and highly data-constrained non-linear force-free field (NLFFF) models over the lifetime of several sigmoidal active regions, where we have captured their magnetic field structure around the times of major flares. We present the topology analysis of a couple of sigmoidal regions pointing us to the probable sites of reconnection. A scenario for eruption is put forward by this analysis. We demonstrate the use of this topology analysis to reconcile the observed eruption features with the standard 3D flare model. Finally, we show a glimpse of how such a NLFFF model of an erupting region can be used to initiate a CME in a global data-constrained MHD simulation in an unprecedented realistic manner. Such simulations can show the effects of solar transients on the near-Earth environment and solar system space weather.

This study used GPS phase fluctuations to investigate irregularities at Tromsø and Ny-Ålesund in Norway from 2007 to 2008. Tromsø locates at auroral latitudes and is inside the auroral oval during nighttime; Ny-Ålesund is in the polar cap; the years 2007 and 2008 belong to the low solar activity period. Therefore, this study showed irregularity behavior in the auroral oval and the polar cap when the influence of solar activity is minimal. The phase-fluctuation index Fp was adopted to characterize GPS phase fluctuations, which relate to the irregularities with size from few to tens kilometers. The investigations include the climatology of Fp and the comparisons between Fp and magnetic indices Kp and AE. The first part shows the occurrence and strength of irregularities, and the second part shows the relations between irregularities and the magnetic variation. Finally, the difference of irregularities in the two regions were detailed examined, and the variations of GPS phase fluctuations and scintillations were also discussed.

Recently it becomes more important to measure the ionosphere over the ocean. Most of the ionospheric area over the ocean are difficult to measure directly for a long time and it prevents the scientists from establishing precise global model of ionosphere. Now many of social requirements, e.g., international aviation glows to know the information over the ocean. National Institute of Information and Communications Technology (NICT) has a long history of operational ionospheric observation with ionosondes since IGY 1957. On the beginning, we had four domestic observatories, Wakkanai, Akita, Kokubunji and Yamagawa. After that Akita was closed and Okinawa joined, we operate these four observatories continuously. In addition, Syowa station in Antarctica has been observing ionosphere by NICT since IGY, too. In addition for research base we have been developing ionospheric observing network in Southeast Asia named SEALION. And as the World Data Center for ionosphere, we exchange and archive a huge number of ionospheric data obtained by foreign institutes. On the base of these experience we suggest four method of ionospheric observation over the ocean

 Dr. Nurul Shazana Abdul Hamid

Equatorial electrojet is an eastward flowing current at about ±3° dip equator. This current intensity is always higher during noontime as it is greatly influenced by the ionization of Earth ionosphere. Apart from that, previous study had shown that EEJ current varies with longitude and latitude as well as solar cycle. The aim of this study is to investigate the peak time of EEJ current at different longitude sectors using simultaneous data in 2009. By eliminating Sq current contribution and normalizing ground-based data from MAGDAS/CPMN, IIG and WDC network, we manage to reach our purpose and gain reliable output. We found out that EEJ is always strongest in South American sector. Our results show that the peak EEJ during fall solar minimum is observed at 11 LT for South American, Indian and Southeast Asian sector but it is 1 hr earlier in African sector.

Ivin Amri Musliman

Associate Prof. Dr. Wayan Suparta

This paper aimed to overview the interaction of the thunderstorm with the ionospheric electric fields during major geomagnetic storms in Antarctica through the GPS tropospheric delays. For the purpose of study, geomagnetic activity and electric fields data for the period from 13 to 21 March 2015 representing the St. Patrick’s Day storm is analyzed. To strengthen the analysis, data for the period of 27 October to 1st November 2003 representing for the Halloween storm is also compared. Our analysis showed that both geomagnetic storms were severe (Ap ≥ 100 nT), where the intensity of Halloween storm is double compared to St. Patrick’s Day storm. For the ionospheric electric field, the peaks were dropped to -1.63 mV/m and -2.564 mV/m for St. Patrick and Halloween storms, respectively. At this time, the interplanetary magnetic field Bz component was significantly dropped to -17.31 nT with Ap > 150 nT (17 March 2015 at 19:20 UT) and -26.51 nT with Ap = 300 nT (29 October 2003 at 19:40 UT). For both geomagnetic storms, the electric field was correlated well with the ionospheric activity where tropospheric delays show a different characteristic.

At a distance of D = 11.5 Mpc, NGC 1448 is one of the nearest galaxies to our own. Yet, the active galactic nucleus (AGN) it hosts was only recently discovered in 2009 through the detection of the high ionization [NeV]λ24.32μm emission line. In this talk, I will present the first multi-wavelength view of the AGN across three wavebands: mid-infrared (MIR) continuum, optical, and X-rays. We observed the source with the Nuclear Spectroscopic Telescope Array (NuSTAR), and combined this data with archival Chandra data to perform broadband X-ray spectral fitting (~0.5-40 keV) of the AGN for the first time. The column density measured from our X-ray spectral analysis, N_H > 2.5 × 10^24 cm^-2, indicates that the nuclear source is buried under a Compton-thick (CT) column of gas across our line-of-sight. This hinders our direct view towards the AGN in X-rays. The 2-10 keV intrinsic luminosity inferred from the best-fitting torus models is L_2-10 = (3.5-7.6) × 10^40 erg/s, making NGC 1448 one of the faintest CTAGNs known to date. In addition to the NuSTAR observation, we also observed the nuclear source at high spatial resolution MIR 12μm continuum using Gemini/T-ReCS which reveals a compact nucleus at the centre of the galaxy. Optical spectroscopy performed for the nucleus using the European Southern Observatory New Technology Telescope re-classified the optical nuclear spectrum as a Seyfert on the basis of the Baldwin-Philips-Terlevich diagnostic diagrams. Our data provide the first identifications of the AGN in NGC 1448 at X-rays, MIR continuum and optical wavelengths. The absorption-corrected 2-10 keV luminosity measured from our X-ray spectral analysis agrees with that predicted from the optical [OIII]λ5007A emission line and the MIR 12μm continuum, further supporting the CT nature of the AGN.

Dr. Md Firoz Khan

Aerosol pollution is of great concern in the tropical regions of Southeast Asia as these particles can pose deleterious impact on human health. The concentration of the particles is greatly influenced by the anthropogenic activities and local monsoonal circulation. These particles decrease visibility, alter cloud albedo and influence climate change via scattering and absorbing radiation. Recent finding suggest fine particles in the urban environment could cause severe Alzheimer’s disease to the population living near the roadways. However, this type of phenomenon has not been fully investigtd in Kuala Lumpur. Thus this study has been carried out to spell out the objectives: a) to study the trend analysis of PNC; b) relate to the source regions; c) to estimate the possible risk on human health. Therefore, the particle number concentration (PNC) was recorded through the use of Nanoscan and Optical particle sizer (OPS) for the wide ranges of 10 nm to 420 nm and 0.300 µm to 10 µm, respectively. Additionally, ozone (O3) at the surface level, meteorological parameters and the GPS coordinates were recorded in 1 min resolution. The equipment and other devices were accommodated to a four wheeler vehicle and the inlets were kept on the roof of the vehicle. This campaign was designed for a period of 4 January 2017 to 11 January 2017 on the main streets of Kuala Lumpur and the nearby areas during the daytime. The campaign was operated at the city centre, residence, industrial and the palm oil plantation areas. Briefly, the results showed that the sharp peaks of PNC were observed in the range of ultrafine and fine mode at the city centre areas as compared to the residential and palm oil plantation areas.