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스카이라디오미터 모델에 따른 에어러솔의 광학적 특성 비교
최용주(Yongjoo Choi),김영성(Young Sung Ghim),손병주(Byung-Ju Sohn) 한국기상학회 2011 대기 Vol.21 No.3
Aerosol optical properties from the radiation measurements by SKYNET PREDE skyradiometers, POM-01 and POM-02 were compared during the inter-calibration campaign at Seoul in February 2009. The monochromatic solar flux at the top of the atmosphere (F?) gave a relative standard deviation (RSD) of 9-10% for both instruments. This comparatively high value of RSD was probably because F? was determined at short time intervals, in the morning and afternoon, using the measurements made in the polluted environment of Seoul. Although POM-02 was more effective in tracking the solar radiation, aerosol optical depths (AODs) from the two instruments were very similar after the cloud screening procedure. The squared correlation coefficients (R²) of single scattering albedo (SSA) and real and imaginary refractive indices between the two instruments was around 0.5 but increased to 0.7-0.8 when only using AOD greater than 0.4. Nevertheless, mean values of the Angstrom exponent, SSA, and the imaginary refractive index of POM-02 were higher than those of POM-01.
판도라 측정 방법에 따른 서울 대류권 NO₂ 수직컬럼밀도의 일치성에 대한 연구
이기열(Giyeol Lee),최용주(Yongjoo Choi) 한국대기환경학회 2024 한국대기환경학회지 Vol.40 No.2
We investigated the consistency of tropospheric nitrogen dioxide vertical column density (NO₂ TropoVCD) depending on the different measurement methods (direct sun and MAX-DOAS mode) from Pandora in Seoul, Korea. The NO₂ TropoVCD from both measurement methods converged within a narrow range (R=0.96), but the slope of the best-fit line was slightly higher than 1 indicating that a higher NO₂ from direct sun, which is reliable, than MAX-DOAS mode. According to the dependence of the difference in measurement azimuth angles between the two modes, a tendency for the MAX-DOAS/direct sun ratio was decreased as it approached zero (the solar zenith angle decreased). The MAX-DOAS/direct sun ratio was linearly increased as the solar zenith angle increased (R=0.93). To understand the difference in measured zenith angle depending on methods, we investigated the NO₂ vertical distribution retrieved from the MAX-DOAS method. The MAX-DOAS/direct sun ratio near sunrise (eastward) and sunset (westward), when the NO₂ vertical gradient is pronounced, is close to 1. However, when the NO₂ concentration vertical gradient is gradual around noon, the NO₂ TropoVCD ratio is less than 1, suggesting that the influence of the NO₂ concentration vertical gradient is not significant. Finally, to investigate the effect of aerosols, we examined the variation in MAX-DOAS/direct sun ratio depending on aerosol optical depth (AOD) measured by AERONET at the same location. Similar to changes in solar zenith angle, the MAX-DOAS/direct sun ratio increased as AOD increased. This AOD-dependent difference is considered to be more pronounced in MAX-DOAS methods that consider changes in climatological aerosols (O₂-O₂) compared to direct sun mode which estimates relatively accurate AOD. We expected that the differences in NO₂ TropoVCD based on the Pandora measurement methods would not only contribute to more accurate satellite data validation but also facilitate improvements in satellite retrieval algorithms through the enhancement of NO₂ vertical distribution accuracy.
남일권(Nam, Ilkwon),최용주(Choi, Yongjoo),김영성(Y. S. Ghim),이강웅(Lee, Gangwoong) 한국외국어대학교 중남미연구소 2018 중남미연구 Vol.37 No.3
중남미 지역 10개 지점 AERONET (AErosol Robotic NETwork)의 직달일사 AOD(aerosol optical depth) 자료를 이용하여 에어로졸 광학특성의 시공간 분포를 분석하였다. Ward의 계층적 군집분석을 적용하여 10개 지점을 안데스와 아마존 그리고 기타 군집으로 구분하였다. 아마존과 안데스 군집에서는 건기에 발생하는 생체 소각의 영향으로 미세입자 AOD가 9월에 가장 높았으며, 아마존 군집은 서아프리카에서 이송되는 광물먼지의 영향으로 연중 조대입자 AOD가 다른 군집에 비해 높았다. 우기에는 강수의 효과로 미세입자 및 조대입자 AOD가 감소하였다. 10개 지점 모두 미세입자 AOD가 높았으며, 지리적 특성에 따라 조대입자의 기여도가 다양하였다. 각 측정지점 간 상관관계 분석 결과, 아마존과 안데스에 위치한 네 지점은 미세입자의 영향이 중요하였다. 기타 군집은 해안에 인접하여 AOD가 낮았고 측정소 간 상관성도 작았다. Direct-sun aerosol optical depth (AOD) data from AErosol Robotic NETwork (AERONET) sites were used to analyze the spatial and temporal variations of aerosol optical properties in Latin America. The Ward"s hierarchical clustering method was applied to 10 AERONET sites to classify them into three groups – Andes, Amazon and the other. The monthly mean of fine mode AOD in the Andes and Amazon was highest in September due to the influence of biomass burning during the dry season. Coarse mode AOD in the Amazon was higher because of the effects of mineral dust transported from West Africa. Both fine and coarse mode AODs decreased during the rainy season because of scavenging by precipitation. The mean values of fine mode AOD were higher than those of coarse mode AOD all the year round at all sites; the contribution of coarse mode aerosol was varied depends on geographical characteristics. The correlation of aerosol optical properties between the sites in Amazon and Andes indicated that the influence of fine mode aerosol was dominant. In the other group which is located close to the coastal area, AODs were low and the correlations between sites were also low.
이주한(Juhan Lee),이정훈(Jeonghoon Lee),최용주(Yongjoo Choi),정창훈(Chang Hoon Jung),박종성(Jong-Sung Park),신혜정(Hye-Jung Shin) 대한기계학회 2021 大韓機械學會論文集B Vol.45 No.3
대기 중 수증기는 미세먼지의 흡습 성장을 야기하고, 입자상 물질의 측정에 있어 오차를 수반한다. 본 연구에서는 미세먼지 측정기 내부의 습기가 측정 결과에 미치는 영향에 대해 분석하였다. 1년간 연속으로 측정된 외기습도, 측정기기 상대습도, PM2.5 및 광산란계수를 관찰했다. 기기 상대습도가 저습으로 유지되는 기간과 그렇지 않은 기간 동안 광산란계수 ≤ 200 Mm<SUP>-1</SUP>와 PM2.5 ≤ 90 ㎍/m³에서 질량산란효율을 계산했고, 저습일 때 PM2.5와 광산란계수의 상관성이 높게 나타났다. 연간 대기 절대습도를 이용해 실제 습기량이 측정에 미치는 영향을 분석했다. 겨울철과 여름철의 외기절대습도 평균은 각각 0.34%와 1.84%로 기기 상대습도가 50%에 도달하는 시간은 약 668일과 46일로 예측되었다. 결론적으로 본 연구를 통하여 외기절대습도에 따른 기기 상대습도의 시간에 대한 변화를 선형 회귀분석해 확산건조기의 수명을 예측할 수 있다. In this study, we analyzed the effect of humidity inside the instrument on the measurement of PM2.5 and the scattering coefficient. For one year, at three sites, we monitored the (i) ambient humidity, (ii) relative humidity (RH) inside the scanning mobility particle spectrometer (SMPS) and the nephelometer, (iii) PM2.5 concentration, and (iv) scattering coefficient. The correlation between PM2.5 and scattering coefficient was better at low humidity than at high humidity. We calculated the actual amount of water vapor from the annual variation of atmospheric absolute humidity (AH) to analyze the effect of humidity on instruments. The average ambient AH during winter and summer is approximately 0.34% and 1.84%, respectively. It is calculated that the RH inside the instrument reaches 50% in approximately 668 days in winter and 46 days in summer. It is the hallmark of this study to predict the lifetime of a diffusion dryer using the linear regression of the change in RH of the instruments according to ambient AH.