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Proceedings Paper

Application of lidar in the observation of atmospheric particulate pollutants in Taipei
Author(s): Yi-Wei Chen; Anupam Hazra; Wei-Nai Chen; M.-L. Lin; P.-H. Lin; Charles C.-K. Chou; J.-P. Chen
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Paper Abstract

For the assessment of climatic impact of aerosols, the knowledge of both the temporal and spatial distributions of aerosol is essential. Laser radar, more popularly known as Lidar, has becoming one of the most powerful techniques for active detection of aerosols in the atmosphere. Lidar can provide vertically resolved of extinction and backscatter coefficients, and thereby the height of the planetary boundary layer or the nighttime residual layer. As the long-term changes in the structure and dynamics of the lower and middle troposphere is now becoming a priority, a pulsed Nd:YAG Lidar system is applied for measuring the vertical distribution of aerosol properties in the metropolitan Taipei. Two years (2004-2005) of aerosol optical depth (AOD) measured by Lidar, Cimel Sunphotometer and MODerate resolution Imaging Spectroradiometer (MODIS) were compared. The AOD shows strong seasonal variation with maximum values (AODLidar > 1, AODCimel > 1 and AODMODIS > 0.39) occurred in April. AODMODIS shows significant underestimation. AODLidar has good correlation with AODCimel, but the Lidar measurement is biased toward lower values as presented by the 0.725 slope in the linear regression. This bias is mostly caused by the Lidar blind distance at the lowest part of the atmosphere. The R-squared of AODCimel and surface PM2.5 concentration is about 0.44. This reflects the fact that the atmospheric boundary layer is often not well-mixed, so aerosols there cannot represent the total AOD value. Particles in the free troposphere also need to be concerned. Further comparison of our Lidar data with the CALIPSO measurements is intended.

Paper Details

Date Published: 1 September 2006
PDF: 8 pages
Proc. SPIE 6299, Remote Sensing of Aerosol and Chemical Gases, Model Simulation/Assimilation, and Applications to Air Quality, 62990E (1 September 2006); doi: 10.1117/12.682637
Show Author Affiliations
Yi-Wei Chen, National Taiwan Univ. (Taiwan)
Anupam Hazra, National Taiwan Univ. (Taiwan)
Wei-Nai Chen, Academia Sinica (Taiwan)
M.-L. Lin, Aletheia Univ. (Taiwan)
P.-H. Lin, National Taiwan Univ. (Taiwan)
Charles C.-K. Chou, Academia Sinica (Taiwan)
J.-P. Chen, National Taiwan Univ. (Taiwan)

Published in SPIE Proceedings Vol. 6299:
Remote Sensing of Aerosol and Chemical Gases, Model Simulation/Assimilation, and Applications to Air Quality
Allen Chu; James Szykman; Shobha Kondragunta, Editor(s)

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