• Title/Summary/Keyword: Atmospheric visibility

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A Comparative Study on the Visibility Characteristics of Naked-Eye Observation and Visibility Meters of Fog over South Korea (남한에서의 안개 사례별 목측과 시정계 계측의 시정 특성 비교)

  • Lee, Hyun-Kyoung;Suh, Myoung-Seok
    • Atmosphere
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    • v.28 no.1
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    • pp.69-83
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    • 2018

  • Most of the researches on fog in South Korea have been done based on the naked-eye observation but the number of observation sites is just 22. Considering the localities of fog and various durations, it is essential to utilize more than 250 visibility meters that measure visibility every minute. In this study, the visibility characteristics of visibility meters were compared with that of the naked-eye observation using one year data, 2016, and radiation fog and advection fog cases were analyzed in detail. The concordance rate of the two data set was 0.96~0.97, but discordance rate was 0.19~0.47. In general, visibility meters observed fog more frequently than naked-eye. The correlation between two data sets is clearly dependent on the visibility and geographic locations (fog/thick fog (< 100 m) of inland: 0.86/0.61; fog/thick fog: 0.65/0.73 of island/coastal site). In both fog cases, the fog events observed by naked-eye were consistently detected by visibility meters, and visibility meters clearly well detected very short fog/thick fogs. Formation and dissipation time of fog for the fog cases were similar but fog duration by visibility meters was shorter because of exclusion of temporary dissipated time. In addition, the visibility meters showed a detailed distribution of fog events that occurred simultaneously over South Korea. It would be useful to analyze the spatial and temporal characteristics of, in particular, thick fog using visibility meters. However, more works are needed for the filtering criteria for analyzing fog using visibility meters alone.

  • https://doi.org/10.14191/Atmos.2018.28.1.069 인용 PDF KSCI

Physico-Chemical Characteristics of Visibility Impairment in a National Park Area (국립공원 지역 시정장애 현상의 물리.화학적 특성)

  • Kim, Kyung-Won
    • Journal of Korean Society for Atmospheric Environment
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    • v.25 no.4
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    • pp.325-338
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    • 2009

  • National parks provide recreation, health, and science to human being. The provision of beautiful landscape view of the national park improves an economic and social phase of a nation. However, visibility impairment frequently occurred in the national park area of Gyeongju. The purpose of this study is to investigate the physical and the chemical characteristics of visibility reduction observed at the national park area of Gyeongju. Optical, chemical, meteorological characteristics and scenic monitoring were performed at the visibility monitoring station of Gyeongju University located at the Seoak section of Gyeongju national park from April 28 to May 9, 2008. Light extinction, light scattering, and light absorption coefficients were continuously measured using a transmissometer, a nephelometer, and an aethalometer, respectively. In order to investigate the impact of aerosol chemistry on visibility impairment, size-resolved aerosols were collected at intervals of 2-hour (from 8 A.M. to 6 P.M.) and 14-hour (from 6 P.M. to 8 A.M.) interval each sampling day. The average light extinction coefficient and the average visual range were measured to be $270{\pm}135\;Mm^{-1}$ and $14.5{\pm}6.3\;km$ during the intensive monitoring period, respectively. It was revealed that sulfate particle was the largest contributor to the light extinction under hazy condition. Organic mass accounted for about 26% of the average light extinction. The mass extinction efficiencies for $PM_{1.0}$, $PM_{2.5}$, and $PM_{10}$ were estimated to be 9.0, 4.7, and $2.7\;m^2\;g^{-1}$ under the consideration of water growth function of hygroscopic aerosols, respectively.

  • https://doi.org/10.5572/KOSAE.2009.25.4.325 인용 PDF KSCI

Estimation of Aerosol Vertical Profile from the MODIS Aerosol Optical Thickness and Surface Visibility Data (MODIS 에어러솔 광학두께와 지상에서 관측된 시정거리를 이용한 대기 에어러솔 연직분포 산출)

  • Lee, Kwon-Ho
    • Journal of the Korean Association of Geographic Information Studies
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    • v.16 no.2
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    • pp.141-151
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    • 2013

  • This study presents a modeling of aerosol extinction vertical profiles in Korea by using the Moderate Resolution Imaging Spectro-radiometer(MODIS) derived aerosol optical thickness(AOT) and ground based visibility observation data. The method uses a series of physical equations for the derivation of aerosol scale height and vertical profiles from MODIS AOT and surface visibility data. The modelled results under the standard atmospheric condition showed small differences with the standard aerosol vertical profile used in the radiative transfer model. Model derived aerosol scale heights for two cases of clean(${\tau}_{MODIS}=0.12{\pm}0.07$, visibility=$21.13{\pm}3.31km$) and hazy atmosphere(${\tau}_{MODIS}=1.71{\pm}0.85$, visibility=$13.33{\pm}5.66km$) are $0.63{\pm}0.33km$ and $1.71{\pm}0.84km$. Based on these results, aerosol extinction profiles can be estimated and the results are transformed into the KML code for visualization of dataset. This has implications for atmospheric environmental monitoring and environmental policies for the future.

  • https://doi.org/10.11108/kagis.2013.16.2.141 인용 PDF KSCI KPUBS