• Title/Summary/Keyword: MODTRAN

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Seasonal Variations of Direct Solar Irradiance with Ground and Air Atmospheric Data Fusion for Peninsular Type Coastal Area (지상 및 고도별 대기측정 자료 융합을 이용한 반도형 해안지역의 직달일사량 계절 변화 연구)

  • Choi, Ji Nyeong;Lee, Sanghee;Seong, Sehyun;Ahn, Ki-Beom;Kim, Sug-Whan;Kim, Jinho;Park, Sanghyun;Jang, Sukwon
    • Korean Journal of Remote Sensing
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    • v.36 no.3
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    • pp.411-423
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    • 2020
  • Localized solar irradiance is normally derived from atmospheric transmission influenced by atmospheric composition and conditions of the target area. Specially, for the area with complex coastal lines such as Taean gun, the accurate estimation of solar irradiance requires for in depth analysis of atmospheric transmission characteristics based on the localized vertical profiles of the key atmospheric parameters. Using MODTRAN (MODerate resolution atmospheric TRANsmission) 6, we report a computational study on clear day atmospheric transmission and direct solar irradiance estimation of Taean gun using the data collected from 3 ground stations and radiosonde measurement over 93 clear days in 2018. The MODTRAN estimated direct solar irradiance is compared with the measurement. The results show that the normalized residual mean (NRM) is 0.28 for the temperature based MODTRAN atmospheric model and 0.32 for the pressure based MODTRAN atmospheric model. These values are larger than 0.1~0.2 of the other study and we understand that such difference represents the local atmospheric characteristics of Taean gun. The results also show that NRM tends to increase noticeably in summer as the temperature increases. Such findings from this study can be very useful for estimation and prediction of the atmospheric condition of the local area with complex coastal lines.

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.

ATOSPHERIC CORRECTION FOR ASTER THERMAL RADIOMETRY USING MODIS ATMOSPHERIC PROFILES

  • Park, Wook;Choi, Jae-Won;Lee, Yoon-Kyung
    • Proceedings of the KSRS Conference
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    • 2008.10a
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    • pp.305-308
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    • 2008
  • The goal of this study is to retrieve ASTER thermal radiometry using a radiative transfer model. The MODTRAN is used for the model because it is easy to use with high spatial resolution and it is possible to specify input parameters such as profiles of temperature, water vapor density, ozone, aerosols and any of the other gasses. Most of parameters such as temperature and water vapor profiles were obtained from the Terra MODIS. The selected ASTER scene images land and coastal area. The surface radiance of ASTER TIR bands were retrieved by MODTRAN and extracted atmospheric profiles from MOD07 and US standard 76 models. Radiance estimated using MOD07 data was systematically lower by about 0.5-1.0 $W/m^2$ sr ${\mu}m$ than that by US standard 76 model between the two cases.

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MODTRAN 모델을 이용한 다목적 실용위성 2호 MSC의 입사복사량 계산

  • Kim, Yong-Seung;Kang, Chi-Ho
    • Aerospace Engineering and Technology
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    • v.1 no.1
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    • pp.173-176
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    • 2002
  • This report summarizes the results of MODTRAN model that are used for the calculation of input radiance of the KOMPSAT-2 Multispectral Camera (MSC). We have calculated the input radiances for four months: January 15, April 15, July 15 and October 15. Annual averages are the arithmetic mean of results from four months. We used the mid-latitude winter and summer for the month of January and July, respectively, while US standard atmospheres are used for April and October. The orbital characteristics of KOMPSAT-2 and the seasonal variations of solar zenith angle over the Korean peninsula were incorporated as inputs to the model. The tropospheric aerosol extinction (visibility = 50 km) was assumed. The surface albedo used in the model calculation represents the global annual mean clear-sky albedo. MSC contract values are found to be considerably greater in the MSC spectral range than the total radiances calculated with the above general conditions. From these results, it can be inferred that the forthcoming MSC images would be somewhat dark. We certainly need a countermeasure for this issue.

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RETRIEVAL OF LAND SURFACE TEMPERATURE FROM MTSAT-1R

  • Kwak, Seo-Youn;Suh, Myoung-Seok;Kang, Jeon-Ho;Kwak, Chong-Heum;Kim, Chan-Soo
    • Proceedings of the KSRS Conference
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    • v.1
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    • pp.250-252
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    • 2006
  • The land surface temperature (LST) can be defined as a weighted average temperature of components which constitute a pixel. The coefficients of split-window algorithm for MTSAT-1R were obtained by means of a statistical regression analysis from radiative transfer simulations using MODTRAN 4.0 for a wide range of atmospheric, satellite viewing angle (SVA) and lapse rate conditions. 6 types of atmospheric profile data imbedded in the MODTRAN 4 are used for the radiative transfer simulations. The RMSE is clearly larger on warm and humid profiles than cold and dry profiles, especially when the satellite viewing angle and lapse rate are large. The derivation of LST equations according to the atmospheric profiles clearly decreased the RMSE without regard to the SVA and lapse rate. The bias and RMSE are decreased as the more controls factors included. This preliminary result indicates that the characteristics of atmosphere, SVA and lapse rate should be included in the LST equation.

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Retrieval of land Surface Temperature from MTSAT-1R

  • Kwak, Seo-Youn;Suh, Myoung-Seok;Kang, Jeon-Ho;Kwak, Chong-Heum;Kim, Chan-Soo
    • Korean Journal of Remote Sensing
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    • v.22 no.5
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    • pp.385-388
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    • 2006
  • The land surface temperature (LST) can be defined as a weighted average temperature of components which constitute a pixel. The coefficients of split-window algorithm for MTSAT-1R were obtained by means of a statistical regression analysis from radiative transfer simulations using MODTRAN 4.0 for a wide range of atmospheric, satellite viewing angle (SVA) and lapse rate conditions. 6 types of atmospheric profile data imbedded in the MODTRAN 4 are used for the radiative transfer simulations. The RMSE is clearly larger on warm and humid profiles than cold and dry profiles, especially when the satellite viewing angle and lapse rate are large. The derivation of LST equations according to the atmospheric profiles clearly decreased the RMSE without regard to the SVA and lapse rate. The bias and RMSE are decreased as the more controls factors included. This preliminary result indicates that the characteristics of atmosphere, SVA and lapse rate should be included in the LST equation.

Augmented Multiple Regression Algorithm for Accurate Estimation of Localized Solar Irradiance (국지적 일사량 산출 정확도 향상을 위한 다중회귀 증강 알고리즘)

  • Choi, Ji Nyeong;Lee, Sanghee;Ahn, Ki-Beom;Kim, Sug-Whan;Kim, Jinho
    • Korean Journal of Remote Sensing
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    • v.36 no.6_1
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    • pp.1435-1447
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    • 2020
  • The seasonal variations in weather parameters can significantly affect the atmospheric transmission characteristics. Herein, we propose a novel augmented multiple regression algorithm for the accurate estimation of atmospheric transmittance and solar irradiance over highly localized areas. The algorithm employs 1) adaptive atmospheric model selection using measured meteorological data and 2) multiple linear regression computation augmented with the conventional application of MODerate resolution atmospheric TRANsmission (MODTRAN). In this study, the proposed algorithm was employed to estimate the solar irradiance over Taean coastal area using the 2018 clear days' meteorological data of the area, and the results were compared with the measurement data. The difference between the measured and computed solar irradiance significantly improved from 89.27 ± 48.08σ W/㎡ (with standard MODTRAN) to 21.35 ± 16.54σ W/㎡ (with augmented multiple regression algorithm). The novel method proposed herein can be a useful tool for the accurate estimation of solar irradiance and atmospheric transmission characteristics of highly localized areas with various weather conditions; it can also be used to correct remotely sensed atmospheric data of such areas.

DEVELOPMENT OF ATMOSPHERIC CORRECTION ALGORITHM FOR HYPERSPECTRAL DATA USING MODTRAN MODEL

  • Kim, Sun-Hwa;Kang, Sung-Jin;Ji, Jun-Hwa;Lee, Kyu-Sung
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.619-622
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    • 2006
  • Atmospheric correction is one of critical procedures to extract quantitative information related to biophysical variables from hyperspectral data. In this study, we attempted to generate the water vapor contents image from hyperspectral data itself and developed the atmospheric correction algorithm for EO-1 Hyperion data using pre-calculated atmospheric look-up-table (LUT) for fast processing. To apply the new atmospheric correction algorithm, Hyperion data acquired June 3, 2001 over Seoul area is used. Reflectance spectrums of various targets on atmospheric corrected Hyperion reflectance images showed the general spectral pattern although there must be further development to reduce the spectral noise.

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Study on an algorithm for atmospheric correction of Landsat TM imagery using MODTRAN simulation

  • Oh, Sung-Nam;Yu, Sung-Yeol;Lee, Hyun-Kyung;Kim, Yong-Sup;Park, Kyung-Won
    • Proceedings of the KSRS Conference
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    • 1998.09a
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    • pp.103-109
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    • 1998
  • A technique on atmospheric correction algorithm for a single band (0.76-0.90 $\mu$m) reflective of Landsat TM imagery has been developed using a radiation transfer model simulation. It proceeds in two steps: First, calculation of the surface reflectance of each pixel based on precomputed planetary albedo functions for actual atmospheres(e. g. radiosonde) and two kinds of atmospheric visibility states. Second, approximate correction of the adjacency pixel effect by taking into account the average reflectance in an 7 $\times$ 7 pixel neighbourhood and using appropriate land cover classification in reflectance. The correction functions are provided by MODTRAN model.

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Model Calculation of Total Radiances for KOMPSAT-2 MSC (다목적실용위성 2호 MSC 총복사량의 모델 계산)

  • 김용승;강치호
    • Korean Journal of Remote Sensing
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    • v.17 no.3
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    • pp.211-218
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    • 2001
  • We have performed the calculation of total radiances for the KOMPSAT-2 Multispectral Camera (MSC) using a radiative transfer model of MODTRAN and examined its results. To simulate four seasonal conditions in the model calculation, we used model atmospheres of mid-latitude winter and summer for calculations of January 15 and July 15, and US standard for April 15 and October 15, respectively. Orbital parameters of KOMPSAT-2 and the seasonal solar zenith angles were taken into account. We assumed that the meteorological range is the tropospheric aerosol extinction of 50 km and surface albedo is the global average of clear-sky albedo of 0.135. MSC contract values are found to be considerably greater in the MSC spectral range than the total radiances calculated with the above general conditions. It is also shown that the spectral behavior of model results with the constant surface albedo differs from the pattern of MSC contract values. From these results, it can be inferred that the forthcoming MSC images would be somewhat dark.