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Measurement of Aerosol Parameters with Altitude by Using Two Wavelength Rotational Raman Signals
Imkang Song,Yonggi Kim,백성훈,Seung-Kyu Park,Hyungki Cha,Sungchul Choi,Chin-Man Chung,김덕현 한국광학회 2010 Current Optics and Photonics Vol.14 No.3
Aerosol size distribution provides good information for predicting weather changes and understanding cloud formation. Aerosol extinction coefficient and backscattering coefficient are measured by many scientists, but these parameters depend not only on aerosol size but on aerosol concentrations. An algorithm has been developed to measure aerosol parameters such as Ångström exponent, color ratio, and LIDAR ratio without any assumptions by using two wavelength rotational Raman LIDAR signals. These parameters are good indicators for the aerosol size. And we can find Ångström exponent, color ratio, and LIDAR ratio under various weather conditions. Finally, it can be seen that the Ångström exponent has an inverse relationship to the particle size of the aerosol and the color ratio is linearly dependent on the aerosol size. An Ångström exponent from 1.2 to 3.1, a color ratio from 0.28 to 1.04, and a LIDAR ratio 66.9 sr at 355 nm and 32.6 sr at 532 nm near the cloud were obtained.
Lidar Measurement of a Full Raman Spectrum of Water by Using a Multichannel Detector
김덕현,Sunghoon Baik,Hyungki Cha,Yonggi Kim,Imkang Song 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1
To measure the phase change of water molecules, we designed a new multi-channel meteorological Raman lidar system that can measure a full spectrum of the ro-vibrational Raman signal for water vapor and the vibrational Raman signal for liquid water simultaneously. To accomplish this, we have designed a receiving system by using a double grating and a holographic notch filter so that the total blocking ratio is approximately 10^-14. Using this system, we have measured a full spectrum of the vibration Raman signal for both liquid water and water vapor by using a multi-channel PMT near a cloud and in a clear atmosphere. From the preliminary experimental results, we can distinguish between cloud droplets and water vapor Raman signals. Using these Raman signals, we can also elucidate a difference between both hydrogen-bonded liquid water and water vapor near clouds and under clear conditions.
The Measurement of the LIDAR Ratio by Using the Rotational Raman LIDAR
Sungchul Choi,백성훈,Seungkyu Park,Hyungki Cha,Imkang Song,김덕현 한국광학회 2010 Current Optics and Photonics Vol.14 No.3
The rotational Raman LIDAR technique has been used to accurately measure aerosol optical properties such as backscatter coefficient, extinction coefficient, and LIDAR ratio. In the case of the vibrational Raman technique, the Ångström exponent, which has wavelength dependence on the particle properties, is assumed to obtain the extinction coefficient. However, this assumed Ångström exponent can cause systematic errors in retrieving aerosol optical properties. In the case of the rotational Raman technique, the aerosol optical properties can be measured without any assumptions about the Ångström exponent. In this paper, the LIDAR ratio was measured by using the rotational Raman LIDAR and vibrational Raman LIDAR in the troposphere. And, the LIDAR ratios measured by these two methods were compared.