ИСТИНА

In National Central University (Chung-Li, Taiwan), research of ionosphere with using a ground-based ionosonde began in 1959. Since 1985, the modern technology and major facilities, such as ground-based GPS receiver, very high-frequency radar, low-latitude ionospheric tomography network, high-frequency Doppler sounder, and digital ionosondes have been set up to investigate the lower ionosphere. The development of ionospheric research grows faster after National Space Origination has been launching a series of FORMOSAT satellites (ROCSAT, FORMOSAT-2, FORMOCAT-3/COSMIC) in 1999, 2004, and 2006. The FORMOSAT satellites, together with theoretical and model developments, significantly promote the ionospheric and space weather research in NCU. The ROCSAT satellite (now renamed FORMOSAT-1) measures the ion composition, density, temperature, and drift velocity at the 600-km altitude in the low-latitude ionosphere; the FORMOSAT-2 satellite is to investigate lightning-induced transient luminous events, polar aurora, and upper atmospheric airglow, and the FORMOSAT-3 probes ionospheric electron density profiles of the globe. On 24 August 2017, FORMOSAT-5, first indigenously developed remote sensing satellite was successfully launched. The mission incorporates the Advanced Ionospheric Probe designed in NCU for studies of ionospheric plasma physics. In the near future, FORMOSAT-7/COSMIC-2 will be employed for studying space weather sciences. Fields of ionospheric research in NCU cover a wide area and concern morphology of the ionosphere for diurnal, seasonal, geophysical, and solar activity variations, as well as the ionosphere response to solar flares, solar wind, solar eclipses, magnetic storms, earthquakes, and tsunami. With continuously advancing, new directions are now connecting to space weather problematic. As example of such new research conducting in NCU, I present results on the ionospheric and space weather study that concerns the ionizing effect produced by energetic electrons in the ionosphere at low latitudes. A phenomenon, called forbidden energetic electrons (FEE) enhancements, is strong long-lasting enhancements of energetic electrons occurred at low altitudes from the equator to low latitudes. We have revealed a significant ionizing impact of FEE enhancements resulting in density increase in the topside ionosphere region. It was found that the energetic particles are injected to the ionosphere from the inner radiation belt. Therefore, the FEE enhancements can be considered as typical example of space weather event, for which main solar wind and geomagnetic drivers should be determined. We perform the statistical study of FEE enhancements for two solar cycles collected from measurements of NOAA/POES satellites. Further study is aimed at developing a probabilistic model of forbidden particle enhancements and their ionospheric effects. The model will be an important part in the space weather monitoring and prediction of ionospheric disturbances such as positive storms and ionospheric scintillations at low latitudes.