ORCID Profile
0000-0002-6944-6962
Current Organisation
Korea Polar Research Institute
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Publisher: MDPI AG
Date: 06-04-2022
Abstract: This paper presents the temporal characteristics of electromagnetic fields produced by cloud-to-ground (CG) lightning flashes associated with Antarctica storms. A total of 51 positive CG (+CG) and 103 negative CG (−CG) flashes have been recorded by a magnetic direction finder (MDF) sensor in King Sejong Station, King George Island. In total, 47 positive and 107 negative return strokes were located, ranges from 32 to 569 km. All CG flashes were detected to occur over the ocean. The return strokes characteristics include the observations of slow front, fast rising, rise time, and pulse duration with geometric mean values of 3.2, 0.53, 3.21, 13.12, and 67.09 µs for +CG flashes, while 3.9, 0.57, 3.72, 20.75, and 69.86 µs for −CG flashes, respectively. Additionally, the average peak currents of +CG and −CG flashes were 4.13 kA and 3.14 kA, respectively. The temporal characteristics of the return strokes of Antarctica storms are comparable to other geographical regions. The smaller peak currents might be due to small magnitude of Antarctica cloud charges when compared to other geographical regions.
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.ENVRES.2022.113998
Abstract: We examined the seasonal cycle of radon concentration observed at King Sejong Station (KSG, 62°S), Antarctic Peninsula, during the period 2013-2016. The distribution of monthly radon concentration was found to be highly positively skewed from March through October (austral autumn to spring) due to large numbers of short-lived periods of high radon concentration. The global atmospheric chemistry model (CAM-Chem), which includes all global terrestrial sources of radon except for those in Antarctica, well reproduces the observed seasonal cycle of monthly-mean radon concentration at KSG. Further offline experiments suggest that uncertainties in radon emissions over South America and the Southern Ocean should be improved for the simulations of radon in Antarctica. The results demonstrate that seasonally varying transport of radon in the boundary layer from South America substantially affects the seasonality of monthly mean radon concentration at KSG. The composite analyses further reveal that high radon events at KSG are the result of a distinct east-west dipole-like structure associated with surface cyclonic circulation over the Bellingshausen Sea and anticyclonic circulation in the Weddell Sea. This atmospheric pattern provides favorable conditions for radon transport into KSG from the northwest. The relationship between radon concentration at KSG and climate variability is also discussed in this study.
Publisher: American Geophysical Union (AGU)
Date: 26-12-2017
DOI: 10.1002/2017JD026833
Publisher: Copernicus GmbH
Date: 18-09-2014
Abstract: Abstract. We report on one year of high-precision direct hourly radon observations at King Sejong Station (King George Island) beginning in February 2013. Findings are compared with historic and ongoing radon measurements from other Antarctic sites. Monthly median concentrations reduced from 72 mBq m−3 in late-summer to 44 mBq m−3 in late winter and early spring. Monthly 10th percentiles, ranging from 29 to 49 mBq m−3, were typical of oceanic baseline values. Diurnal cycles were rarely evident and local influences were minor, consistent with regional radon flux estimates one tenth of the global average for ice-free land. The predominant fetch region for terrestrially influenced air masses was South America (47–53° S), with minor influences also attributed to aged Australian air masses and local sources. Plume dilution factors of 2.8–4.0 were estimated for the most terrestrially influenced (South American) air masses, and a seasonal cycle in terrestrial influence on tropospheric air descending at the pole was identified and characterised.
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