Browsing by Author "Kim, WH"
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- ItemAnalysis of a decade of Asian outflow of PM10 and TSP to Gosan, Korea: also incorporating Radon-222(Elsevier B.V., 2015-05) Crawford, J; Chambers, SD; Kang, CH; Griffiths, AD; Kim, WHTen years of aerosol and Radon–222 (radon) data from Gosan, Korea, were analyzed. Seasonal cycles were strongly linked to changes in fetch and time of year. We estimated that 7.21 t/m y of PMio aerosol pass Gosan in the atmospheric boundary layer, increasing annually by 0.3 t/m y. Contributions to aerosol loading were characterized by fetch: South China, North China, Korea and Japan. While the highest, and most variable, contributions typically originated from South China, these air masses contributed to only 6% of the overall dataset. PM10 distributions were broader from South and North China than for Korea or Japan, reflecting differences in natural/anthropogenic soil sources, and number/distribution of large point sources. Employing radon to select air masses more representative of targeted fetch regions typically resulted in greater reported pollutant concentrations and rates of change over the decade. Estimated rates of PM10 increase from North China and Korea over the decade were 1.4 and 0.9 μg/m3 y, respectively. Total suspended particulate (TSP) elemental analysis indicated that the (non–sea–salt) nss–SO42− content of aerosols has been gradually increasing over the past decade and more recently an increase in NO3− was seen. However, on average, rates of increase in nss–SO42− have reduced since 2007, which were higher in South than North China. © 2020 Elsevier B.V.
- ItemBackground level of atmospheric radon-222 concentrations at Gosan Station, Jeju Island, Korea in 2011(Korea Science, 2014-04-20) Kim, WH; Ko, HJ; Hu, CG; Lee, HY; Lee, CK; Chambers, SD; Williams, AG; Kang, CHReal-time monitoring of hourly atmospheric radon (Rn-222) concentration was performed throughout 2011 at Gosan station, Jeju Island, one of the least polluted regions in Korea, in order to characterize the background levels, and temporal variations on diurnal to seasonal time-scales. The annual mean radon concentration for 2011 was mBq , and the seasonal cycle was characterized by a broad winter maximum, and narrow summer minimum. Mean monthly radon concentrations, in descending order of magnitude, were Oct > Sep > Feb > Nov > Jan > Dec > Mar > Aug > Apr > Jun > May > Jul. The maximum monthly mean value (3595 mBq , October), exceeded the minimum value (1243 mBq , July), by almost a factor of three. Diurnal composite hourly concentrations increased throughout the night to reach their maximum (2956 mBq ) at around 7 a.m., after which they decreased to their minimum value (2259 mBq ) at around 3 p.m. Back trajectory analyses indicated that the highest radon events typically exhibited long-term continental fetch over Asia before arriving at Jeju. In contrast, low radon events were generally correlated with air mass fetch over the North Pacific Ocean. Radon concentrations typical of predominantly continental, and predominantly oceanic fetch, differed by a factor of 3.8. (C) KISTI. All Rights Reserved.
- ItemConcentration variability of atmospheric radon and gaseous pollutants at background area of Korea between 2017 and 2018(Korea Institute of Science and Technology Information, 2022-02-25) Kim, WH; Yang, HS; Bu, JO; Kang, CH; Song, JM; Chambers, SDThe concentrations of radon in the atmosphere were measured at the Gosan site of Jeju Island during 2017-2018, in order to investigate the time-series variation characteristics and the dependency of airflow transport pathways. The mean 222Rn concentration was 2,480 mBq m-3, and its monthly concentration in November was 3,262 mBq m-3, more than twice as that in July (1,459 mBq m-3). The diurnal radon concentrations increased throughout the nighttime to the maximum (2,862 mBq m-3) at around 7 a.m., then gradually decreased throughout the daytime by the minimum (1,997 mBq m-3) at around 3 p.m. The seasonal and monthly variations of CO, NO2, O3 showed a roughly similar pattern to that of radon for the same period, as high in winter and low in summer. The cluster back trajectory analysis described that about 60 % of overall airflow pathways was influenced by the airflow from China. The concentrations of radon and gaseous pollutants were relatively high as the airflow was influenced by China continent, but comparatively much lower as influenced by the northern Pacific Ocean. © The Authors - open access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licence.
- ItemImproving estimates of pollution outflow at Gosan using 222Rn(World Meteorological Organization, 2015-11-01) Chambers, SD; Kang, CH; Williams, AG; Crawford, J; Griffiths, AD; Kim, WHThe best understanding of climatic, ecological and health effects from increasing Southeast Asian emissions will likely be achieved by models coupled to detailed emission inventories and remote sensing data. To improve model accuracy and forecast horizons, careful evaluation against appropriate observations is essential. To minimize the chance of misleading comparisons, it is important to ensure ground-based reference observations are well matched with the model output, especially regarding fetch regions and scales of observation. To quantify upstream emissions based on ground-based observations it is necessary to: (i) understand the measurement “footprint”, (ii) identify observations most representative of air that has been in good contact with the surface over which it has travelled, and has not been significantly diluted by fronts or deep convection in transit, (iii) ensure observations are representative of the whole boundary layer (BL), (iv) minimize the influence of local emissions, (v) characterize changes in mixing depth, and (vi) characterize evolving “background” concentrations.
- ItemImproving the representation of cross-boundary transport of anthropogenic pollution in East Asia using radon-222(Taiwan Association for Aerosol Research, 2016-01-01) Chambers, SD; Kang, CH; Williams, AG; Crawford, J; Griffiths, AD; Kim, KH; Kim, WHWe report on 10 years of hourly atmospheric radon, CO, and SO2 observations at Gosan Station, Korea. An improved radon detector was installed during this period and performance of the detectors is compared. A technique is developed whereby the distribution of radon concentrations from a fetch region can be used to select air masses that have consistently been in direct contact with land-based emissions, and have been least diluted en route to the measurement site. Hourly radon concentrations are used to demonstrate and characterise contamination of remote-fetch pollution observations by local emissions at this key WMO GAW site, and a seasonally-varying 5-hour diurnal sampling window is proposed for days on which diurnal cycles are evident to minimise these effects. The seasonal variability in mixing depth and “background” pollutant concentrations are characterised. Based on a subset of observations most representative of the important regional fetch areas for this site, and least affected by local emissions, seasonal estimates of CO and SO2 in air masses originating from South China, North China, Korea and Japan are compared across the decade of observations. 2016, © Taiwan Association for Aerosol Research
- ItemThe use of radon in the analysis of a decade of Asian outflow of PM10 and TSP to Gosan, Korea(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-10) Crawford, J; Chambers, SD; Kang, CH; Griffiths, AD; Kim, WHNot provided to ANSTO Library.