• Title/Summary/Keyword: mass extinction efficiency

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Estimation of Particle Mass Concentration from Lidar Measurement (라이다 관측자료를 이용한 미세먼지 농도 산정)

  • Kim, Man-Hae;Yeo, Huidong;Sugimoto, Nobuo;Lim, Han-Cheol;Lee, Chul-Kyu;Heo, Bok-Haeng;Yu, Yung-Suk;Sohn, Byung-Ju;Yoon, Soon-Chang;Kim, Sang-Woo
    • Atmosphere
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    • v.25 no.1
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    • pp.169-177
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    • 2015
  • Vertical distribution of particle mass concentrations was estimated from 8-year elastic-backscatter lidar and sky radiometer data, and from ground-level PM10 concentrations measured in Seoul. Lidar ratio and mass extinction efficiency were determined from aerosol optical depth (AOD) and ground-level PM10 concentrations, which were used as constraints to estimate particle mass concentration. The mean lidar ratio (with standard deviation) and mass extinction efficiency for the entire 8-year study period were $60.44{\pm}23.17$ sr and $3.69{\pm}3.00m^2g^{-1}$, respectively. The lidar ratio did not vary significantly with the ${\AA}ngstr{\ddot{o}}m$ exponent (less than ${\pm}10%$); however, the mass extinction efficiency decreases to $1.82{\pm}1.67m^2g^{-1}$ (51% less than the mean value) when the ${\AA}ngstr{\ddot{o}}m$ exponent is less than 0.5. This result implies that the particle mass concentration from lidar measurements can be underestimated for dust events. Seasonal variation of the particle mass concentration estimated from lidar measurements for the boundary layer, was quite different from ground-level PM10 measurements. This can be attributable to an inhomogeneous vertical distribution of aerosol in the boundary layer.

The KALION Automated Aerosol Type Classification and Mass Concentration Calculation Algorithm (한반도 에어로졸 라이다 네트워크(KALION)의 에어로졸 유형 구분 및 질량 농도 산출 알고리즘)

  • Yeo, Huidong;Kim, Sang-Woo;Lee, Chulkyu;Kim, Dukhyeon;Kim, Byung-Gon;Kim, Sewon;Nam, Hyoung-Gu;Noh, Young Min;Park, Soojin;Park, Chan Bong;Seo, Kwangsuk;Choi, Jin-Young;Lee, Myong-In;Lee, Eun hye
    • Korean Journal of Remote Sensing
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    • v.32 no.2
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    • pp.119-131
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    • 2016
  • Descriptions are provided of the automated aerosol-type classification and mass concentration calculation algorithm for real-time data processing and aerosol products in Korea Aerosol Lidar Observation Network (KALION, http://www.kalion.kr). The KALION algorithm provides aerosol-cloud classification and three aerosol types (clean continental, dust, and polluted continental/urban pollution aerosols). It also generates vertically resolved distributions of aerosol extinction coefficient and mass concentration. An extinction-to-backscatter ratio (lidar ratio) of 63.31 sr and aerosol mass extinction efficiency of $3.36m^2g^{-1}$ ($1.39m^2g^{-1}$ for dust), determined from co-located sky radiometer and $PM_{10}$ mass concentration measurements in Seoul from June 2006 to December 2015, are deployed in the algorithm. To assess the robustness of the algorithm, we investigate the pollution and dust events in Seoul on 28-30 March, 2015. The aerosol-type identification, especially for dust particles, is agreed with the official Asian dust report by Korean Meteorological Administration. The lidar-derived mass concentrations also well match with $PM_{10}$ mass concentrations. Mean bias difference between $PM_{10}$ and lidar-derived mass concentrations estimated from June 2006 to December 2015 in Seoul is about $3{\mu}g\;m^{-3}$. Lidar ratio and aerosol mass extinction efficiency for each aerosol types will be developed and implemented into the KALION algorithm. More products, such as ice and water-droplet cloud discrimination, cloud base height, and boundary layer height will be produced by the KALION algorithm.

Physico-Chemical Characteristics of Visibility Impairment by Airborne Pollen (공중화분에 의한 시정장애 현상의 물리적 및 화학적 특성 규명)

  • Kim, Kyung-Won
    • Journal of Korean Society for Atmospheric Environment
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    • v.22 no.6
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    • pp.863-875
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    • 2006
  • Intensive visibility monitoring was conducted to investigate physical and chemical characteristics of visibility impairment by airborne pollen. Light attenuation coefficients were optically measured by a transmissometer, a nephelometer, and an aethalometer. Elemental, ionic, and carbonaceous species were chemically analyzed on the filters collected by $PM_{2.5}$ and $PM_{10}$ samplers. Aerosol size distribution was analyzed using a cascade impactor during airborne pollen period. Airborne pollen count was calculated using a scanning electron microscope. Airborne pollen was emitted into the atmosphere in springtime and funker degraded visibility through its scattering and absorbing the light. Average light extinction coefficient was measured to be $211{\pm}36Mm^{-1}$ when airborne pollen was not observed. But it increased to $459{\pm}267Mm^{-1}$ during the airborne pollen period due to increase of average $PM_{2.5}$ and $PM_{10}$ mass concentration and relative humidity and airborne pollen count concentration for $PM_{10}$, which were measured to be $46.5{\pm}29.1{\mu}g\;m^{-3},\;97.0{\pm}41.7{\mu}g\;m^{-3},\;54.1{\pm}11.6%$, and $68.2{\pm}89.7m^{-3}$, respectively. Average light extinction efficiencies for $PM_{2.5}$ and $PM_{10}$ were calculated to be $5.9{\pm}0.9$ and $4.5{\pm}0.8m^2 g^{-1}$ during the airborne pollen period. Light extinction efficiency for $PM_{10}$ increased further than that for $PM_{2.5}$. The average light extinction budget by airborne pollen was estimated to be about 24% out of the average measured light extinction coefficient during the airborne pollen period.

Modeling of Smog Characteristics in Seoul during the Fall,1993 (서울시의 1993년 가을 스모그 특성모사)

  • 백남준;이성준;김용표;문길주;조영일
    • Journal of Korean Society for Atmospheric Environment
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    • v.10 no.2
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    • pp.137-145
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    • 1994
  • A visibility analysis model based on the Mie theory is applied to the measurements during the fall, 1993 in Seoul. Model estimations of the total extinction coefficient $b_{ext}$, and the particle scattering coefficient, $b_{sp}$ are in good agreement with the measured values by a transmissometer and a nephelometer, respectively. These values show strong dependency on the mass loading of fine particles( $D_{p}$ <3.0${\mu}{\textrm}{m}$) but show no apparent relation with that of coarse particles(3.0${\mu}{\textrm}{m}$$D^{p}$ <10${\mu}{\textrm}{m}$). Relative humidity plays an important role in determining the size of particles which in turn, affects the optical efficiency of aerosol. Based on the composition analysis with cut size nitrate concentration is higher than the sulfate concentration in PM3-10 but they are comparable to each other in PM3. Considering in 1985, it demonstrates a drastic increase of nitrate concentration between 1985 and 1993. It is found that measured and estimated light extinction budget were in good agreement within 10% and that scattering by particles is responsible for about 50-55% and 70-80 % of total extinction during clear and smoggy periods respectively.y.

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The Study of PM10, PM2.5 Mass Extinction Efficiency Characteristics Using LIDAR Data (라이다 데이터를 이용한 PM10, PM2.5 질량소산효율 특성 연구)

  • Kim, TaeGyeong;Joo, Sohee;Kim, Gahyeong;Noh, Youngmin
    • Korean Journal of Remote Sensing
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    • v.37 no.6_2
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    • pp.1793-1801
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    • 2021
  • From 2015 to June 2020, the backscattering coefficients of 532 and 1064 nm measured using LIDAR and the depolarization ratio at 532 nm were used to separate the backscattering coefficient at 532 nm as three types as PM10, PM2.5-10, PM2.5 according to particle size. The mass extinction efficiency (MEE) of three types was calculated using the mass concentration measured on the ground. The overall mean values of the calculated MEE were 5.1 ± 2.5, 1.7 ± 3.7, and 9.3 ± 6.3 m2/g in PM10, PM2.5-10, and PM2.5, respectively. When the mass concentration of PM10 and PM2.5 was low, higher than average MEE was calculated, and it was confirmed that the MEE decreased as the mass concentration increased. When the MEE was calculated for each type according to the mixing degree of Asian dust, PM2.5-10 was twice at pollution aerosol as high as 2.1 ± 2.8 m2/g, compare to pollution-dominated mixture, dust-dominated mixture, and pure dust of 1.1 ± 1.8, 1.4 ± 3.3, 1.1 ± 1.5 m2/g, respectively. However, PM2.5 MEE showed similar values irrespective of type: 9.4 ± 6.5, 9.0 ± 5.8, 10.3 ± 7.5, and 9.1 ± 9.0 m2/g. The MEE of PM10 was 5.6 ± 2.9, 4.4 ± 2.0, 3.6 ± 2.9, and 2.8 ± 2.4 m2/g in pollution aerosol (PA), pollution-dominated mixture (PDM), dust-dominated mixture (DDM), and pure dust (PD), respectively, and increased as the dust ratio value decreased. Even if the same type according to the same mass concentration or Asian dust mixture was shown, as the PM2.5/PM10 ratio decreased, the MEE of PM2.5-10 decreased and the MEE of PM2.5 showed a tendency to increase.

The Effect on Visibility of the Chemical Composition of Fine Particles in the Gwangju Area (광주지역 미세먼지의 화학적 조성이 시정에 미치는 영향에 관한 연구)

  • Jung, Sun-A;Lim, Cheol-Soo;Jo, Mi-Ra;Lee, Sang-Bo;Kim, Jung-Soo;Shin, Eun-Sang
    • Journal of Environmental Health Sciences
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    • v.44 no.1
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    • pp.1-14
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    • 2018
  • Objectives: The purpose of this study is to investigate the main cause of visibility impairment by analyzing the contributions of the light extinction coefficient of major air pollution components and the change of the light extinction coefficient by relative humidity. Methods: The characteristics of the light extinction coefficient calculated by the photochemical method using fine particle component data measured in 2015 in the Gwangju area were examined. Results: The extinction efficiency per unit mass of $PM_{2.5}$ particles was $4.5m^2/g$ and that of $PM_{10-2.5}$ particles was $0.6m^2/g$. This difference indicates that most of the visibility impairment in Gwangju was caused by $PM_{2.5}$ particles. When visibility was poor, the contribution of ammonium sulphate and ammonium nitrate was significantly increased. Relative humidity was also a major cause of visibility decay. The influx of air currents in Gwangju was mostly caused by the long distance movement of pollutants emitted from the eastern part of China. Ammonium sulphate and ammonium nitrate, which are hygroscopic secondary contaminants, were the main causative agents of visibility impairment. Conclusions: Ammonium sulphate and ammonium nitrate were the main causative agents of visibility impairment in Gwangju. The influx of air currents in Gwangju was mostly caused by the long distance movement of pollutants emitted from the eastern part of China.

Fire Resistance and Thermal Stability Study of Fire-Retarded Polypropylene Systems by Using Cone Calorimeter and Thermogravimetry (콘 칼로리미터와 TGA를 이용한 할로겐 계통의 난연제를 첨가한 폴리프로필렌 수지의 난연성 및 열 안정성에 관한 연구)

  • 곽성복;정찬화;남재도;김준형;최미애
    • Polymer(Korea)
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    • v.24 no.6
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    • pp.777-786
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    • 2000
  • Fire resistance and thermal stability of polypropylene composite systems were investigated by using several halogenated fire-retardants such as decabromodiphenyl oxide (DBDPO) and chlorinated paraffin wax (CPW). The fire resistance of composite systems was thoroughly examined by measuring limited oxygen index (LOI, ASTM D2863, ISO 4589) and characteristic properties of cone calorimetry(ASTM E1354, ISO 5660) heat release rates (HRR), time to ignition (TTI), total heat release (THR), effective heat of combustion (EHC), mass loss rates, etc. Comparing the cone calorimetry experimental results of the halogen flame retardants, DBDPO exhibited twice higher efficiency than CPW in polypropylene systems, and the LOI also showed similar trends to cone calorimetry. The thermo-oxidative stability of the composite systems was increased about 30-5$0^{\circ}C$ in thermogravimetry analysis.Collectively, the combustion, extinction and thermally-stable characteristics of flame retardants were identified in this study.

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