• 대기
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• 제17권4호
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• pp.407-420
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• 2007

Optical characteristics of aerosols in Seoul are investigated from the measurements of sky radiance by Skyradiometer at Yonsei University from December 2005 to November 2006. Aerosol optical depth (AOD) shows a maximum in June due to weak ventilation and particle growth by aging process and hygroscopic effect. Single scattering albedo (SSA) and Angstrom Exponent (AE) show the lowest value in spring due to the Asian dust. It is clear that coarse mode is dominant in spring and fine mode is dominant in summer from the volume size distribution measured in this study. The explanations on the changes of aerosol loadings are provided through the correlation between AOD and AE, while the pattern of wavelength dependency related to particle size is shown through the correlation between SSA and AE. Backward trajectory analysis by HYSPLIT provides information about origin of aerosol, which allows us to classify the case according to the source region and the path distance. Although the direction of backward trajectory traces back mostly to west, coarse mode particle is dominant in the case of long pathway and fine mode particle is dominant in the case of short pathway. This discrepancy is caused by the regional difference of emitted particles.

• 대한원격탐사학회지
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• 제36권2_1호
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• pp.93-101
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• 2020

본 연구는 국내 최초로 안면도, 고산, 광주, 서울에서 측정된 AERONET 선포토미터 자료를 편광소멸도(δ)와 단산란 알베도(SSA)를 이용하여 에어로졸의 유형을 PD, DDM, PDM, NA, WA, MA, SA의 7가지 유형으로 구분하고 계절별, 연도별 발생빈도와 유형별 AOD변화를 살펴보았다. 오염입자(NA, WA, MA, SA를 합한 비율)의 비율은 각각 58.9, 46.2, 59.5, 67.1%로 서울이 가장 높고 고산이 가장 낮았다. 연간 비율 변화는 NA는 증가하고 PD, DDM은 감소하는 경향을 보였다. 유형별 AOD는 NA가 모든 사이트에서 가장 높은 값을 보였다. 또한, NA의 비율과 AOD는 지속적으로 증가하는 추세를 보였다.

• 대한원격탐사학회지
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• 제29권4호
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• pp.407-413
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• 2013

본 연구에서는 에어로졸의 종류에 따른 광흡수 특성을 표시할 수 있는 새로운 에어로졸 파라미터인 Modified Aerosol Factor(MAF)를 산출하였다. MAF는 AERONET의 선포토미터로부터 산출되는 4 파장(440, 675, 870 그리고 1020 nm)의 단산란알베도로부터 도출되었다. 에어로졸 종류에 단산란알베도 값이 파장 증가에 따라 다른 형태를 보이는 점으로부터 4파장의 단산란알베도를 이용하여 선형회귀분석을 수행하고 분석값의 기울기 값을 산출하였다. 먼지입자는 기울기 값이 양의 값을 보이고, 순수한 먼지입자 일수록 높은 값을 보였다. 다른 종류의 에어로졸이 혼합됨에 따라 기울기 값은 감소하였다. 먼지입자를 제외한 오염입자와 smoke 입자는 음의 값을 보였다. 광흡수 특성의 차이를 파악하기 위하여 1020 nm에서의 단산란알베도 값을 보정하였다. 보정된 단산란알베도와 기울기 값을 합하여 MAF를 도출하였다. MAF는 오염입자와 smoke 입자는 -1, 먼지입자는 1.5의 값을 보였으며, 서로 다른 에어로졸 종류별로 광흡수 특성이 높을수록 낮은 값의 분포를 보였다.

• 한국대기환경학회지
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• 제33권2호
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• pp.97-107
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• 2017

Columnar aerosol properties retrieved from solar radiation were investigated at the Yongin (YGN) SKYNET site over seven years from October 2008 to October 2015. Hourly averages were calculated when the data were available, and back trajectories were calculated to examine the effects of regional transport. Data recovery rate was low at 6.6%, primarily because solar radiation was measured only under daytime clear-sky conditions. Mean values of the fine-mode volume fraction (FMVF) as well as its seasonal variation were similar to those of $PM_{2.5}/PM_{10}$ although the coarse-mode fraction of column aerosols tended to be slightly larger. The values of single scattering albedo (SSA) and FMVF were lower in spring due to the effects of mineral dust, and higher in summer due to secondarily-formed inorganic ions. Back trajectories were grouped into five clusters according to the directions of transport paths. Aerosol loading was highest for Cluster 2 from the northwest, but SSA and FMVF were not particularly high or low because aerosols were composed of various materials with different properties. Aerosol loading was lowest for Cluster 5 from the Pacific Ocean passing through the south end of Japan, whose SSA and FMVF were highest as secondarily-formed inorganic ions were mixed.

• 천문학회보
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• 제37권1호
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• pp.73.1-73.1
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• 2012

We present the results of dust scattering simulations carried out for the Orion Eridanus Superbubble region by comparing them with observations made in the far-ultraviolet. The albedo and the phase function asymmetry factor (g-factor) of interstellar grains were estimated as well as the distance and thickness of the dust layers. The results are: 0.39-0.45 for the albedo and 0.25-0.65 for the g-factor, in good agreement with previous determinations and theoretical predictions. The distance of the assumed single dust layer, modeled for the Orion Molecular Cloud Complex, was estimated to be -110 pc and the thickness ranged from -130 at the core to -50 pc at the boundary for the region of the present interest, implying that the dust cloud is located in front of the Superbubble. The simulation result also indicates that a thin (-10 pc) dust shell surrounds the inner X-ray cavities of hot gas at a distance of -70-90 pc.

• 한국대기환경학회지
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• 제22권2호
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• pp.235-247
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• 2006

Aerosol indirect radiative forcing of climate change is considered the most uncertain forcing of climate change over the industrial period, despite numerous studies demonstrating such modification of cloud properties and several studies quantifying resulting changes in shortwave radiative fluxes. Detection of this effect is made difficult by the large inherent variability in cloud liquid water path (LWP): the dominant controlling influence of LWP on optical depth and albedo masks any aerosol influences. Here we have used ground-based remote sensing of cloud optical depth (${\tau}_c$) by narrowband radiometry and LWP by microwave radiometry to determine the dependence of optical depth on LWP, thereby permitting examination of aerosol influence. The method is limited to complete overcast conditions with liquid-phase single layer clouds, as determined mainly by millimeter wave cloud radar. The results demonstrate substantial (factor of 2) day-to-day variation in cloud drop effective radius at the ARM Southern Great Plains site that is weakly associated with variation in aerosol loading as characterized by light-scattering coefficient at the surface. The substantial scatter suggests the importance of meteorological influences on cloud drop size as well, which should be analyzed in the further intensive studies. Meanwhile, it is notable that the decrease in cloud drop effective radius results in marked increase in cloud albedo.

• 천문학회보
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• 제37권2호
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• pp.98.1-98.1
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• 2012

We present the results of dust scattering simulations carried out for the Orion-Eridanus Superbubble region by comparing them with observations made in the far-ultraviolet. The albedo and the phase function asymmetry factor (g-factor) of interstellar grains were estimated, as were the distance and thickness of the dust layers. The results are as follows: [0.43]_(-0.04)^(+0.02) for the albedo and [0.43]_(-0.2)^(+0.2) for the g-factor, in good agreement with previous determinations and theoretical predictions. The distance of the assumed single dust layer, modeled for the Orion Molecular Cloud Complex, was estimated to be ~110 pc, and the thickness ranged from ~130 at the core to ~50 pc at the boundary for the region of present interest, implying that the dust cloud is located in front of the superbubble. The simulation result also indicates that a thin (~10 pc) dust shell surrounds the inner X-ray cavities of hot gas at a distance of ~70-90 pc.

• Journal of the Optical Society of Korea
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• 제19권5호
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• pp.444-448
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• 2015

We describe the radiative transfer of a Gaussian beam in a water medium using the Monte Carlo method offering basic propagation behaviors. The simulation shows how the energy of the initial Gaussian beam is redistributed as it propagates in coastal water, and also depicts the dependence of the propagation behavior on inherent optical properties of the ocean water such as the single scattering albedo as well as on laser beam parameters, e.g. the M squared. Our results may widen the applicability of LIDARs by providing a couple of design considerations for a bathymetric LIDAR.

• 대기
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• 제23권1호
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• pp.85-92
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• 2013

2001년 4월 제주 고산기후관측소에서 AERONET sun/sky radiometer와 MPL을 통해 관측된 에어로졸 광학적 두께, 단산란 알베도, 비대칭 변수, 에어로졸 소산계수 프로파일 등을 대기복사모델의 입력 자료로 이용하여 대기가열효과를 산정하고, 이들 광학변수가 대기복사가열률에 미치는 영향을 분석하였다. 본 연구에서는 NCAR Climate Community Model (CCM-3.6)에 포함되어 있는 복사 모듈인 Column Radiation Model (CRM-2.1.2)을 연직 54층으로, AERONET sun/sky radiometer로부터 관측된 4 파장 (440, 670, 870, 그리고 1020 nm)에서의 관측 자료를 19개의 파장에서 계산 가능하도록 수정하였다. 에어로졸층이 존재하지 않은 맑은 날 (4월 14일과 16일)은 지표면과 대기상단에서의 에어로졸 직접복사강제력이 각각 $-20{\sim}-25\;W\;m^{-2}$와 $-10{\sim}-15\;W\;m^{-2}$로, 대기 중 흡수는 $+10{\sim}+15\;W\;m^{-2}$였다. 에어로졸층이 관측된 4월 15일과 4월 17~18일의 경우 지표면, 대기, 대기상단의 에어로졸 복사강제력이 맑은 날에 비해 3~4배 정도 크게 나타났다. 4월 14일과 16일에의 대기복사가열률 (${\Delta}H$)는 $1{\sim}2\;K\;day^{-1}$ 범위에서 산출되었으며, 4월 15일과 4월 17~18일에는 MPL 관측에서 보여지는 에어로졸층에서의 ${\Delta}H$와 ${\Delta}H_{aerosol}$가 각각 $3\;K\;day^{-1}$ 이상과 $1{\sim}3\;K\;day^{-1}$ 범위에서 산정되었다. 에어로졸 광학적 두께와 비대칭 변수의 변화에 따른 에어로졸층의 ${\Delta}H$ 변화는 미미하였으나, 단산란 알베도의 10% 변화는 지표면과 대기상단에서의 에어로졸 직접복사강제력의 30%, 대기복사강제력의 약 60%, 그리고 에어로졸층 ${\Delta}H$의 약 35% 변화를 유발하였다. 이는 에어로졸 광학적 두께 10% 변화와 비교하여 대기흡수 또는 에어로졸층의 가열 및 냉각 효과가 6배 가량 큰 결과로, 태양복사를 효과적으로 잘 흡수하는 에어로졸의 양에 의해 대기 가열 또는 ${\Delta}H$가 크게 좌우됨을 의미한다. 2001년 4월부터 2008년 3월까지 제주 고산기후관측소에서의 AERONET sun/sky radiometer 관측 자료를 이용하여 계산한 ${\Delta}H$와 ${\Delta}H_{aerosol}$의 월변화를 보면, ${\Delta}H$는 4~8월 사이에 대류권 하부에서 약 $1.0\;K\;day^{-1}$ 이상으로 뚜렷하게 나타났으나, ${\Delta}H_{aerosol}$의 경우 2월부터 6월까지 고도 2 km 이하에서 약 $0.8\;K\;day^{-1}$ 이하의 범위에서 나타나는데, 이는 대부분의 에어로졸이 지표면 부근의 대기경계층에 존재하며, 봄철 황사와 오염 에어로졸의 증가에 의한 영향으로 판단된다.

• 대기
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• 제18권4호
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• pp.287-297
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• 2008

The vertical profiles and optical properties of Asian dust are investigated using ground-based measurements from 1998 to 2002. Vertical profiles of aerosol extinction coefficient are evaluated using MPL (Micro Pulse Lidar) data. Optical parameters such as aerosol optical thickness ($\tau$), ${\AA}ngstr\ddot{o}m$ exponent ($\alpha$), single scattering albedo ($\omega$), refractive index, and volume size distribution are analyzed with sun/sky radiometer data for the same period. We can separate aerosol vertical profiles into three categories. First category named as 'Asian dust case', which aerosol extinction coefficient is larger than $0.15km^{-1}$ and dust layer exists from surface up to 3-4km. Second category named as 'Elevated aerosol case', which aerosol layer exists between 2 and 6km with 1-2.5km thickness, and extinction coefficient is smaller than $0.15km^{-1}$. Third category named as 'Clear sky case', which aerosol extinction coefficient appears smaller than $0.15km^{-1}$. and shows that diurnal variation of background aerosol in urban area. While optical parameters for first category indicate that $\tau$ and $\alpha$ are $0.63{\pm}0.14$, $0.48{\pm}0.19$, respectively. Also, aerosol volume concentration is increased for range of 1 and $4{\mu}m$, in coarse mode. Optical parameters for second category can be separated into two different types. Optical properties of first type are very close to Asian dust cases. Also, dust reports of source region and backward trajectory analyses assure that these type is much related with Asian dust event. However, optical properties of the other type are similar to those of urban aerosol. For clear sky case, $\tau$ is relatively smaller and $\alpha$ is larger compare with other cases. Each case shows distinct characteristics in aerosol optical parameters.