https://repository.kopri.re.kr/handle/201206/14784 2026-04-15T01:55:01Z https://repository.kopri.re.kr/handle/201206/14842 Title: Observations for the Ionosphere Using European Incoherent Scatter (EISCAT) in the Dayside Polar Cap/Cusp and Auroral Region Authors: Jee, Geonhwa; 지은영; 김은솔; 곽영실; Lee, Changsup; Kwon, Hyuck-Jin; Kim, Jieun; Ham, Young-Bae; Lee, Ji-Hee; Kim, Jeong-Han; 양태영; 감호식 Abstract: Korea Polar Research Institute (KOPRI) and Korea Astronomy and Space Institute (KASI) have been participating in the European Incoherent Scatter (EISCAT) Scientific Association as an affiliate institution in order to observe the polar ionosphere since 2015. During the period of December 16？21, 2016 and January 3？9, 2018, the observations for the polar ionospheric parameters such as the electron density profiles, ion drift, and electron/ion temperature are carried out in the polar cap/ cusp region by the EISCAT Svalbard radar (ESR). The purpose of the observations is to investigate the characteristic of the winter ionosphere in the dayside polar cap/cusp region. In this paper, we briefly report the results of the ESR observations for winter daytime ionosphere and also the simultaneous observations for the ionosphere-thermosphere system together with the balloon-borne instrument High-Altitude Interferometer WIND Experiment (HIWIND) performed by the High Altitude Observatory (HAO), National Center for Atmospheric Research (NCAR). We further introduce our research activities using long-term EISCAT observations for the occurrence of ion upflow and the climatology of the polar ionospheric density profiles in comparison with the mid-latitude ionosphere. Finally, our future research plans will briefly be introduced. 2023-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/14846 Title: Hemispheric asymmetry of the polar ionospheric density investigated by ESR and JVD radar observations and TIEGCM simulations for the solar minimum period Authors: 김은솔; Jee, Geonhwa; Wenbin Wang; 곽영실; 심자순; Ham, Young-Bae; 김용하 Abstract: The ionospheric density displays hemispheric asymmetries in the polar region due to various hemispheric differences, for example, in the offset between geographic and geomagnetic poles and in the geomagnetic field strength. Using ground-based ionospheric measurements from Vertical Incidence Pulsed Ionospheric Radar with Dynasonde analysis at Jang Bogo Station (JBS), Antarctica and from EISCAT Svalbard Radar (ESR) where both sites are located mostly in the polar cap, we investigate the hemispheric differences in the ionospheric density between the northern and southern hemispheres for geomagnetically quiet and solar minimum condition. The results are also compared with Thermosphere Ionosphere Electrodynamic Global Circulation Model (TIEGCM) simulations. The observations show larger density and stronger diurnal and seasonal variations at JBS in the southern hemisphere than at Svalbard in the northern hemisphere. The diurnal variations of the density peak height are also observed to be much larger at JBS. In both hemispheres, the ionospheric density is significantly reduced in winter due to the limited solar production at high geographic latitudes, but TIEGCM considerably overestimates winter density, which is even larger than summer density, especially in the northern hemisphere. Also existed are the differences in the equinoctial asymmetry between the observations and the simulations: the daytime F-region density is observed to be larger in fall than in spring in both hemispheres, but TIEGCM shows the opposite. In general, most of the observed asymmetrical density are much weaker in the model simulation, which may result from lack of proper magnetospheric forcings and neutral dynamics in the model. 2023-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/14858 Title: Response of Meteor Plasma Trails Observed by Meteor Radar to Geomagnetic Activity Authors: Kam Hosik; Kwak Young-Sil; Lee, Changsup; Kim Jeong-Heon; Hong Junseok; Kim Yong Ha; Kim, Jeong-Han Abstract: From meteor radar observations typically measuring neutral winds and temperatures in the upper atmosphere, we showed that under-dense meteor plasma trails respond to geomagnetic activity. Depending on the geomagnetic activity conditions, the parameters of the under-dense trail echoes show substantial anomalies, and their responses are immediate. As geomagnetic activity increases, the decay time decreases up to about 10% at Kp = 8, while both the returned signal power and radial velocity error increase. In addition, the types of diffuse evolution vary with geomagnetic activity, resulting in strong geomagnetic activity that immediately affects the trail. The evolution of the trail is affected not only by the ambient mesospheric neutral atmospheric properties but also by electromagnetic effects, such as strong electric fields inside meteor trails. Furthermore, our findings suggest that the geomagnetic effect should be considered when estimating atmospheric parameters from MR during a geomagnetically active period. 2023-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/14892 Title: Low-Frequency Wave Activity in the Ocean-Ross Ice Shelf-Atmosphere System Authors: Zabotin N.; Godin O. A.; Bromirski P. D.; Jee, Geonhwa; Lee, Won Sang; Yun, Sukyoung; Zabotina L. Abstract: The main subject of this study is the low-frequency (with the periods longer than 2 hr) wave processes in the coupled regional system of the Ross Ice Shelf (RIS), the Ross Sea and the atmosphere above them. We investigate possible causal relationships between the wave activity in the three media using a unique set of geophysical instruments: a hydrophone measuring pressure variations on the seafloor, a network of seismometers measuring vertical displacements of the RIS surface, and a Dynasonde system measuring wave characteristics at the ionospheric altitudes. We present an extension of the previously introduced theoretical model of the coupled resonance vibrations of the RIS that quantifies the connection between the ocean tide and the resonance vibrations of the RIS. The ocean tide is confirmed as the most significant source of excitation of the resonances. Analysis of average power spectra in year-long data sets reveals multiple harmonics of the tide (eight) detected by the RIS seismometers while only three are detected by the seafloor sensor. This may represent a confirmation of the effect of resonance-related broadband amplification predicted by the model. Several peaks in the spectrum of RIS vibrations have periods different from the periods of nearby tidal constituents and may be associated with broad-scale resonance RIS vibrations. Resonances may play a role in maintaining the coupled atmosphere-ocean wave activity. Our results reveal a statistically significant correlation between the spectra of the vertical displacements of the RIS and the spectra of the atmospheric waves. 2023-01-01T00:00:00Z