• Title, Summary, Keyword: Atmospheric transmittance

Search Result 40, Processing Time 0.033 seconds

The Solar Atmospheric Transmittance Data for Peak Cooling Load Calculation using ETD Method (실효온도차법에 의한 최대열부하계산용 일사 대기투과율)

  • Kim, D.C.;Seo, J.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.4 no.4
    • /
    • pp.316-322
    • /
    • 1992
  • A simplified TAC method was developed for the selection of solar atmospheric transmittance data fundamental to the calculation of design solar radiation for the peak cooling load calculation using ETD method. The summer and autumn solar atmospheric transmittance data of the 11 major cities in Korea were obtained. Based on the simplified TAC method, the atmospheric transmittance data were selected by the TAC 2.5% of July instead of the TAC 2.5% of June through September for summer and the TAC 5.0% of October instead of the TAC 2.5% of October and November for autumn. Results show that the atmospheric transmittance data at solar noon were in the range of 0.61-0.66 for summer and 0.78-0.82 for autumn except for Pusan and Incheon.

  • PDF

A Combined Atmospheric Radiative Transfer Model (CART): A Review and Applications

  • Chen, Xiuhong;Wei, Heli
    • Journal of the Optical Society of Korea
    • /
    • v.14 no.3
    • /
    • pp.190-198
    • /
    • 2010
  • A set of radiative transfer software named CART (Combined Atmospheric Radiative Transfer) has been developed to rapidly calculate atmospheric transmittance and background radiance. The spectral resolution of CART is $1cm^{-1}$, and the spectral region covers from 1 to $25000cm^{-1}$. CART has five characteristic features, and it can be applied to many fields. The features and applications of CART are summarized in detail.

Effect of the East Asian Reference Atmosphere on a Synthetic Infrared Image (동아시아 표준 대기가 합성 적외선 영상에 미치는 효과)

  • Shin, Jong-Jin
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.9 no.4
    • /
    • pp.97-103
    • /
    • 2006
  • A synthetic infrared image can be effectively utilized in various fields such as the recognition and tracking of targets as long as its quality is good enough to reflect the real situations. One way to improve its quality is to use the reference atmosphere which best describes atmospheric properties of regional areas. The east asian reference atmosphere has been developed to represent atmospheric properties of the east asia including Korean peninsula. However, few research has been conducted to examine the effects of this east asian reference atmosphere on the modeling and simulation. In this regard, this paper analyzes the effects of the east asian reference atmosphere on a synthetic infrared image. The research compares the atmospheric transmittance, the surface temperature, and the radiance obtained by using the east asian reference atmosphere with those of the midlatitude reference atmosphere which has been widely applied in the east asia. The results show that the differences of the atmospheric transmittance, the surface temperature, and the radiance between the east asian reference atmosphere and the midlatitude reference atmosphere are significant especially during the daytime. Therefore, it is recommended to apply the east asian reference atmosphere for generating a synthetic infrared image with targets in the east asia.

Improvement of Field Calibration of a Transmissometer for Visibility Measurement

  • Kim Kyung W.;Kim Young J.
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.21 no.E2
    • /
    • pp.49-56
    • /
    • 2005
  • A long-path transmissometer is one of the optical instruments widely used to measure atmospheric light extinction coefficient without enclosing a light beam and perturbing aerosols. Over the past two decades, a number of measurements have been carried out using the long-path transmissometer manufactured by OPTEC, Inc. Calibration of the transmissometer should be performed when any component of the transmissometer system is interchanged or installation condition is changed. For a better calibration of the transmissometer, application of a modified calibration method for the existing neutral density (ND)-filter method was recommended for the computation of the atmospheric transmittance using model MODTRAN 4 in this study. It was revealed that the measured light extinction coefficient from the transmissometer which was calibrated using the existing ND-filter method could be overestimated due to the assumption of the atmospheric transmittance suggested by OPTEC, Inc. The uncertainty of the measured light extinction coefficient from the transmissometer calibrated based on the modified ND-filter method was calculated to be approximately $13Mm^{-1}$.

ANALYSIS OF IRSIGNAL CHARACTERISTICS OF A SHIP FOR NON-UNIFORM ATMOSPHERIC CONDITIONS (비균일 대기상태를 고려한 함정의 적외선 신호 특성 분석)

  • Choi, J.H.;Kim, D.H.;Han, K.I.;Ha, N.K.;Jang, H.S.;Lee, S.H.;Kim, D.G.;Kim, T.K.
    • Journal of computational fluids engineering
    • /
    • v.22 no.1
    • /
    • pp.88-94
    • /
    • 2017
  • The IR signal entering into a sensor is composed of the following components: the self-emitted component directly from the object surface, the reflected components of the solar and sky irradiance at the object surface, and the scattered component by the atmosphere without reference to any object surfaces. The self-emitted and reflected components from the object can be lowered by the atmospheric layer between the object and the IR sensor. The principle factors influencing the atmospheric transmittance are the air temperature, the relative humidity and the observation distance. Previous studies on IR signal transmission through the atmosphere are focused on uniform atmospheric conditions and the non-uniform nature of the atmosphere was not properly treated in modeling. In this study, we use the local atmospheric transmittance to simulate the non-uniform atmosphere in analyzing the IR signal from the object surface. The results show that the nonuniform analysis of the atmosphere becomes more important as the wavelength of IR signal increases.

APPLYING ALOS PRISM DATA TO RETRIEVE THE ATMPSPHERIC TRANSMITTANCE

  • Liu, Gin-Rong;Lin, Tang-Huang;Tsai, Fuan;Li, Kuo-Kuang
    • Proceedings of the KSRS Conference
    • /
    • /
    • pp.310-313
    • /
    • 2007
  • In this study, a new technique for atmospheric transmittance estimated from ALOS PRISM data is developed. It is based on satellite's observing radiances of different view angles and assumes that the cause of difference in radiances is the different view angles. The ALOS PRISM has three independent optical systems for viewing forward and backward and producing a stereoscopic image along the satellite's track. This stereo pair data can be used to estimate the transmittance according to the radiative transfer theory. This derived transmittance will be validated by the AERONET data and compared with the MODTRAN4 simulation results. Results show that the higher the land cover albedo, the better the derived transmittance compared to the AERONET data. Besides, this technique also shows the transmittance retrieval will be underestimated for the low land cover albedo.

  • PDF

The Variation of Radiation Transmittance by the cw 1.07 ㎛ Fiber Laser and Water Aerosol Interaction

  • Koh, Hae Seog;Shin, Wan Soon;Jeon, Min Yong;Park, Byung Suh
    • Journal of the Optical Society of Korea
    • /
    • v.16 no.3
    • /
    • pp.191-195
    • /
    • 2012
  • Among the atmospheric effect of laser propagation, the variations of the radiation transmittance by water aerosol evaporation have quantitatively been investigated. When the aerosol was exposed by a 1.07 ${\mu}m$ cw fiber laser, the increased amount of the transmittance variation was a maximum of 19.1% and the volume concentration variation of aerosol was observed as an increasing of laser intensity. Also, significant irregularity of refractive index was not found in the heated area during the continuous laser heating.

RETRIEVAL OF VERTICAL OZONE PROFILE USING SATELLITE SOLAR OCCULTATION METHOD AND TESTS OF ITS SCNSITIVITY (태양 엄폐법에 의한 연직 오존 분포 도출과 민감도 실험)

  • 조희구;윤영준;박재형;이광목;요코다타쓰야
    • Journal of Astronomy and Space Sciences
    • /
    • v.15 no.1
    • /
    • pp.119-138
    • /
    • 1998
  • Recently measurements of atmospheric trace gases from satellite are vigorous. So the development of its data processing algorithm is important. In this study, retrievalof vertical ozone profile from the atmospheric transmittance measured by satellite solar occultation method and its sensitivity to temperature and pressure are investigated. The measured transmittance from satellite is assumed to be given by the limb path transmittance simulated using annual averaged Umkehr data for Seoul. The limb path transmittance between wavelengths $9.89{\mu}m$ and $10.2{\mu}m$ is simulated with respect to tangent heights using the ozone data of HALOE SIDS(Hallogen Occultation Experiment Simulated Instrument Data Set) as an initial profile. Other input data such as pressure and temperature are also from HALOE SIDS. Vertical ozone profile is correctly retrieved from the measured transmittance by onion-peeling method from 50km to 11km tangent heights with the vertical resolution of 3km. The bias error of $\pm0.001$ in measured transmittance, the forced error of $\pm3K$ in each layer temperature, and the forced $\pm3%$ error in each layer pressure are assumed for sensitivity tests. These errors are based on the ADEOS/ILAS error limitation. The error in ozone amount ranges from -6.5% to +6.9% due to transmittance error, from -9.5% to +10.5% due to temperature error, and from -5.1% to +5.4% due to pressure error, respectively. The present study suggests that accurate vertical ozone profile can be retrieved from satellite solar occultation method. Accuracy of vertical temperature profile is especially important in the retrieval of vertical ozone profile.

  • PDF

Study on IR Signature Characteristics for different Transmittance over the Korean South Sea during Summer and Winter Seasons (거제도 해양의 여름 및 겨울철 환경에서 거리에 따른 대기투과도를 고려한 함정의 적외선 신호 특성 분석)

  • Choi, Jun-Hyuk;Kim, Jung-Ho;Jung, In-Hwa;Lee, Phil-Ho;Kim, Tae-Kuk
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.13 no.2
    • /
    • pp.320-327
    • /
    • 2010
  • The IR signature data of a ship is mainly affected by location, meteorological conditions(atmosphere temperature, wind direction and velocity, humidity etc.), atmospheric transmittance, solar position and ship surface temperature etc. The IR signatures received by a remote sensor at a given temperature and wavelength region is consisted of the self-emitted component directly from the object surface, the reflected component of the solar irradiation at the object surface, and the scattered component by the atmosphere without ever reaching the object surface. Computer simulations for prediction of the IR signatures of ships are very useful to examine the effects of various sensor positions. In this paper, we have acquired the IR signature for different sensor positions by using computer program for prediction of the IR signatures. The numerical results show that the IR signature contrast as compared to the background sea considering the meteorological conditions, solar and sky irradiations.