• 대기
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• 제25권1호
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• pp.117-127
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• 2015

The presences of clouds significantly influence the accuracy of ozone retrievals from satellite measurements. This study focuses on the influence of clouds on Ozone Monitoring instrument (OMI) ozone profile retrieval based on an optimal estimation. There are two operational OMI cloud products; OMCLDO2, based on absorption in $O_2-O_2$ at 477 nm, and OMCLDRR, based on filling in Fraunhofer lines by rotational Raman scattering (RRS) at 350 nm. Firstly, we characterize differences between $O_2-O_2$ and RRS effective cloud pressures using MODIS cloud optical thickness (COT), and then compare ozone profile retrievals with different cloud input data. $O_2-O_2$ cloud pressures are significantly smaller than RRS by ~200 hPa in thin clouds, which corresponds to either low COT or cloud fraction (CF). On the other hand, the effect of Optical centroid pressure (OCP) on ozone retrievals becomes significant at high CF. Tropospheric ozone retrievals could differ by up to ${\pm}10$ DU with the different cloud inputs. The layer column ozone below 300 hPa shows the cloud-induced ozone retrieval error of more than 20%. Finally, OMI total ozone is validated with respect to Brewer ground-based total ozone. A better agreement is observed when $O_2-O_2$ cloud data are used in OMI ozone profile retrieval algorithm. This is distinctly observed at low OCP and high CF.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제13권1호
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• pp.67-72
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• 2013

Cloud detection and analysis from satellite images has been a topic of research in many atmospheric and environmental studies; however, it still is a challenging task for many reasons. In this paper, we propose a new method for cloud-type classification using fuzzy logic. Knowing that visible-light images of clouds contain thickness related information, while infrared images haves height-related information, we propose a two-layered fuzzy logic based on the input source to provide us with a relatively clear-cut threshold in classification. Traditional noise-removal methods that use reflection/release characteristics of infrared images often produce false positive cloud areas, such as fog thereby it negatively affecting the classification accuracy. In this study, we used the color information from source images to extract the region of interest while avoiding false positives. The structure of fuzzy inference was also changed, because we utilized three types of source images: visible-light, infrared, and near-infrared images. When a cloud appears in both the visible-light image and the infrared image, the fuzzy membership function has a different form. Therefore we designed two sets of fuzzy inference rules and related classification rules. In our experiment, the proposed method was verified to be efficient and more accurate than the previous fuzzy logic attempt that used infrared image features.

• 천문학회보
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• 제37권1호
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• pp.80.2-80.2
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• 2012

We firstly present the unified Far-UV continuum map of the Taurus-Auriga-Perseus (TPA) complex, one of the largest local associations of dark cloud located in (l, b)=([152,180], [-28, 0]), by merging both FIMS and GALEX. The FUV continuum map shows that dust extinction correlate well with the FUV around the complex. It says strong absorption in the dense Taurus cloud and Auriga cloud. Although the column density of Perseus and California cloud is similar to Taurus' and Auriga's, Perseus and California cloud do not show strong absorption in FUV because they are more distant than Taurus and Auriga cloud. We also present the dust scattering simulation based on Monte Carlo Radiative Transfer technique. Through the result of Monte-Carlo dust scattering simulation and comparing the result with FIMS-GALEX unified map we gain deeper understanding related to the spatial dust distribution of TPA region. As a preliminary result of the simulation we present the most probable front face, thickness, albedo, and asymmetry factor in this region, respectively. Through this work we can show a certain inclination of the spatial dust distribution. During this study we have developed the FUV dust scattering simulation code using Monte-Carlo method. We expect that it will be generally used to simulate dust scattering in the Galaxy.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.430-432
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• 2008

Visible channel calibration method using deep convective clouds (DCCs) is developed. The method has advantages that visible radiance is not sensitive to cloud optical thickness (COT) for deep convective clouds because visible radiance no longer increases when COT exceeds 100. Therefore, once DCCs are chosen appropriately, and then cloud optical properties can be assumed without operational ancillary data for the specification of cloud conditions in radiative transfer model. In this study, it is investigated whether IR measurements can be used for the selection of DCC targets. To construct appropriate threshold value for the selection of DCCs, the statistics of cloud optical properties are collected with MODIS measurements. When MODIS brightness temperature (TB) at 11 ${\mu}$ m is restricted to be less than 190 K, it is shown that more than 85% of selected pixels show COT ${\geq}$ 100. Moreover, effective radius ($r_e$) distribution shows a sharp peak around 20 ${\mu}m$. Based on those MODIS observations, cloud optical properties are assumed as COT = 200 and $r_e$ = 20 ${\mu}m$ for the simulation of MODIS visible (0.646 ${\mu}m$) band radiances over DCC targets.

• 한국환경과학회지
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• 제11권12호
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• pp.1235-1242
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• 2002

The purpose of this study is to estimate wet deposition flux and to investigate wet deposition characteristics by using the ADOM model. Wet deposition flux of highly reactive $SO_2$ is estimated by applying observed meteorological parameters and concentrations of chemical species to the ADOM model. Wet deposition is largely dependent on large scale precipitation and cloud thickness. Wet deposition flux of sulfate depends on $SO_2$ oxidation in clouds. When large amount of $SO_2$ is converted to sulfate, deposition flux of sulfate increases, but wet deposition flux of $SO_2$ is small. On the whole, the pattern of sulfate wet deposition flux agrees with the typical pattern of sulfate wet deposition that is high in the summer(July) and low in the winter(January).

• 대한안전경영과학회지
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• 제4권3호
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• pp.35-43
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• 2002

For the unconfined vapor cloud explosion accident by the continuous release of gas-liquid flow of various saturated liquids in a vessel at ground level, overpressures were estimated and analyzed with various release conditions and materials by TNT equivalency model with vapor dispersion. We found that at same release conditions, overpressure showed n-heptane > xylene > n-hexane > toluene > n-heptane > benzene, respectively and that overpressure was increased with increasing the hole diameter and the storage pressure, but it was increased with decreasing the wind speed, the interested distance, and the vessel thickness.

• 물과 미래
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• 제28권6호
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• pp.229-236
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• 1995

강수의 물리과정에 입각한 호우모형이 전일권(1994)에 의하여 개발되었다. 본 논문에서 이를 수정하였다. 본는 연구 모형에서 구성한 주요 부분은 포화증기압, 구름두께, 운정기압에 관한 것이다. 기존 모형과 달리 본 연구 모형의 입력자료로써 위성에 의해 측정된 운정기온과 알베도를 사용하였다. 본 연구에서 기존의 포화증기압 방정식보다 현실에 가까운 방정식을 획득하였으며 기존 방정식의 단점을 해결하였다. 또한 운정기온과 운정기압 추정에 사용된 매개변수가 소거되었으며 계산시간도 단축되었다. 본 연구 모형을 전주지점의 호우사상에 적용하여 검증한 결과 모형의 출력인 총강우량과 강우 패턴이 실측치에 잘 부합되었다.

• 신재생에너지
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• 제7권1호
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• pp.22-28
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• 2011

The surface solar radiations were calculated and analyzed with spatial resolutions (4 km and 1 km) using by GWNU (Gangneung-Wonju National University) solar radiation model. The GWNU solar radiation model is used various data such as aerosol optical thickness, ozone amount, total precipitable water and cloud factor are retrieved from Moderate Resolution Imaging Spectrometer (MODIS), Ozone Monitoring Instrument (OMI), MTSAT-1R satellite data and output of the Regional Data Assimilation Prediction System(RDAPS) model by Korea Meteorological Administration (KMA), respectively. The differences of spatial resolutions were analyzed with input data (especially, cloud factor from MTSAT-1R satellite). And the Maximum solar radiation by GWNU model were found in Andong, Daegu and Jinju regions and these results were corresponded with the MTSAT-1R cloud factor.

• 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.

• 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.