• Title/Summary/Keyword: atmospheric

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A Study on Atmospheric Correction in Satellite Imagery Using an Atmospheric Radiation Model (대기복사모형을 이용한 위성영상의 대기보정에 관한 연구)

  • Oh, Sung-Nam
    • Atmosphere
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    • v.14 no.2
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    • pp.11-22
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    • 2004
  • A technique on atmospheric correction algorithm to the multi-band reflectance of Landsat TM imagery has been developed using an atmospheric radiation transfer model for eliminating the atmospheric and surface diffusion effects. Despite the fact that the technique of satellite image processing has been continually developed, there is still a difference between the radiance value registered by satellite borne detector and the true value registered at the ground surface. Such difference is caused by atmospheric attenuations of radiance energy transfer process which is mostly associated with the presence of aerosol particles in atmospheric suspension and surface irradiance characteristics. The atmospheric reflectance depend on atmospheric optical depth and aerosol concentration, and closely related to geographical and environmental surface characteristics. Therefore, when the effects of surface diffuse and aerosol reflectance are eliminated from the satellite image, it is actually corrected from atmospheric optical conditions. The objective of this study is to develop an algorithm for making atmospheric correction in satellite image. The study is processed with the correction function which is developed for eliminating the effects of atmospheric path scattering and surface adjacent pixel spectral reflectance within an atmospheric radiation model. The diffused radiance of adjacent pixel in the image obtained from accounting the average reflectance in the $7{\times}7$ neighbourhood pixels and using the land cover classification. The atmospheric correction functions are provided by a radiation transfer model of LOWTRAN 7 based on the actual atmospheric soundings over the Korean atmospheric complexity. The model produce the upward radiances of satellite spectral image for a given surface reflectance and aerosol optical thickness.

The Study on Establishment of the Urban Atmospheric Environment Map for Analysis of Atmospheric Environment in Busan Metropolitan City (부산광역시 대기환경 파악에 활용가능한 도시대기환경지도 작성에 관한 연구)

  • Kim, Min-Kyoung;Jung, Woo-Sik;Lee, Hwa Woon
    • Journal of Environmental Science International
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    • v.24 no.6
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    • pp.807-817
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    • 2015
  • In this study the urban atmospheric environment map in Busan was made and it consist of the atmospheric environment element map and the atmospheric environment analysis map. The atmospheric environment element map covered the topography, the urban climate, the air pollutant emission, ozone and PM10 concentrations in Busan and the atmospheric environment analysis map included the thermal environment and the wind flow by using WRF meteorological numerical simulation. The meteorological elements from 2007 to 2011 in Busan were used in this study. As a result, in the center of Busan and Buk-gu along to the Nakdong river was the temperature high. To analyze the air flow of Busan 3 clusters depending on the wind direction were extracted with the cluster analysis. The results of the analysis on the detailed wind field of each cluster showed that the weak ventilation could be happened locally at the specific meteorological condition.

Determination of Urban Surface Aerodynamic Characteristics Using Marquardt Method

  • Zhang, Ning;Jiang, Weimei;Gao, Zhiqiu;Hu, Fei;Peng, Zhen
    • Wind and Structures
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    • v.12 no.3
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    • pp.281-283
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    • 2009
  • Marquardt method is used to estimate the aerodynamic parameters in urban area of Beijing City, China, including displacement length (d), roughness length ($z_0$) and friction velocity (u*) and drag coefficient. The surface drag coefficient defined as the ratio between friction velocity and mean wind speed is 0.125 in our research, which is close to typical urban area value. The averaged d and $z_0$ are 1.2 m and 7.6 m. d and $z_0$ change with direction because of the surface heterogeneity over urban surface and reach their maximum values at S-SW sector, this tendency agrees with the surface rough element distribution around the observation tower.

Dispersion Modeling of Fine Carbon Fibers in Atmospheric Boundary Layer (대기경계층에서 미세 섬유 확산 모델링)

  • Kim, Seog-Cheol;Hwang, Jun-Sik;Lee, Sang-Kil
    • Journal of the Korea Institute of Military Science and Technology
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    • v.11 no.3
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    • pp.169-175
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    • 2008
  • A fine carbon fibers dispersion model is implemented to calculate the scattering range and ground level concentration of carbon fibers emitted at certain altitudes of atmospheric boundary layer. This carbon fibers dispersion model was composed by coupling a commonly used atmospheric dispersion model and an atmospheric boundary layer model. The atmospheric boundary layer model, applying the Monin-Obukov Similarity Rule obtained from measurement input data at ground level, was used to create the atmospheric boundary layer structure. In the atmospheric dispersion model, the Lagrangian Particle Model and the Markov Process were applied to calculate the trajectory of scattered carbon fibers relative to gravity and aerodynamic force, as well as carbon fibers specification.

Absolute Atmospheric Correction Procedure for the EO-1 Hyperion Data Using MODTRAN Code

  • Kim, Sun-Hwa;Kang, Sung-Jin;Chi, Jun-Hwa;Lee, Kyu-Sung
    • Korean Journal of Remote Sensing
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    • v.23 no.1
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    • pp.7-14
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    • 2007
  • Atmospheric correction is one of critical procedures to extract quantitative information related to biophysical variables from hyperspectral imagery. Most atmospheric correction algorithms developed for hyperspectral data have been based upon atmospheric radiative transfer (RT) codes, such as MODTRAN. Because of the difficulty in acquisition of atmospheric data at the time of image capture, the complexity of RT model, and large volume of hyperspectral data, atmospheric correction can be very difficult and time-consuming processing. In this study, we attempted to develop an efficient method for the atmospheric correction of EO-1 Hyperion data. This method uses the pre-calculated look-up-table (LUT) for fast and simple processing. The pre-calculated LUT was generated by successive running of MODTRAN model with several input parameters related to solar and sensor geometry, radiometric specification of sensor, and atmospheric condition. Atmospheric water vapour contents image was generated directly from a few absorption bands of Hyperion data themselves and used one of input parameters. This new atmospheric correction method was tested on the Hyperion data acquired on June 3, 2001 over Seoul area. Reflectance spectra of several known targets corresponded with the typical pattern of spectral reflectance on the atmospherically corrected Hyperion image, although further improvement to reduce sensor noise is necessary.

Research and Development for Atmospheric Sciences and Earthquake of Korea (기상.지진 R&D의 최근 동향 및 발전 방향)

  • Kim, Do-Yong;Oh, Jai-Ho;Lee, Chan-Goo;Hahm, In-Kyeong
    • Atmosphere
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    • v.17 no.4
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    • pp.455-462
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    • 2007
  • Of late, natural disasters are becoming more frequent and the damages caused by these are quite substantial. All these are mainly due to a climate change. Many scientists from various countries are therefore engaged in research on atmospheric sciences and seismology. Korea meteorological administration (KMA) has established an advanced research and development center "CATER" for atmospheric sciences and earthquake. CATER has been managing and promoting the five major fields of research such as strategic meteorology, applied meteorology, climate change/countermeasure, earthquake, and research planning for CATER. Compared to 2006, CATER in 2007 has increased the funding by 7% and 5% for the climate change/countermeasure and the earthquake research fields, respectively. Also, the distribution rate of funding in 2007 has increased in 12% for basic research, 6% for university research organization, and 13% for the local area. CATER is trying to construct basic system and infrastructure for atmospheric sciences and earthquake research based on information technology. KMA has also a middle-term vision plan "World Best 365" for atmospheric science and earthquake research. These will give us a chance to become advanced nation in field of atmospheric sciences and seismology.

Characterization of Individual Atmospheric Aerosols Using Quantitative Energy Dispersive-Electron Probe X-ray Microanalysis: A Review

  • Kim, Hye-Kyeong;Ro, Chul-Un
    • Asian Journal of Atmospheric Environment
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    • v.4 no.3
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    • pp.115-140
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    • 2010
  • Great concerns about atmospheric aerosols are attributed to their multiple roles to atmospheric processes. For example, atmospheric aerosols influence global climate, directly by scattering or absorbing solar radiations and indirectly by serving as cloud condensation nuclei. They also have a significant impact on human health and visibility. Many of these effects depend on the size and composition of atmospheric aerosols, and thus detailed information on the physicochemical properties and the distribution of airborne particles is critical to accurately predict their impact on the Earth's climate as well as human health. A single particle analysis technique, named low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA) that can determine the concentration of low-Z elements such as carbon, nitrogen and oxygen in a microscopic volume has been developed. The capability of quantitative analysis of low-Z elements in individual particle allows the characterization of especially important atmospheric particles such as sulfates, nitrates, ammonium, and carbonaceous particles. Furthermore, the diversity and the complicated heterogeneity of atmospheric particles in chemical compositions can be investigated in detail. In this review, the development and methodology of low-Z particle EPMA for the analysis of atmospheric aerosols are introduced. Also, its typical applications for the characterization of various atmospheric particles, i.e., on the chemical compositions, morphologies, the size segregated distributions, and the origins of Asian dust, urban aerosols, indoor aerosols in underground subway station, and Arctic aerosols, are illustrated.