Application of lidar in the observation of atmospheric particulate pollutants in Taipei

Yi-Wei Chen; Anupam Hazra; Wei-Nai Chen; M.-L. Lin; P.-H. Lin; Charles C.-K. Chou; J.-P. Chen

doi:10.1117/12.682637

1 September 2006 Application of lidar in the observation of atmospheric particulate pollutants in Taipei

Yi-Wei Chen, Anupam Hazra, Wei-Nai Chen, M.-L. Lin, P.-H. Lin, Charles C.-K. Chou, J.-P. Chen

Proceedings Volume 6299, Remote Sensing of Aerosol and Chemical Gases, Model Simulation/Assimilation, and Applications to Air Quality; 62990E (2006) https://doi.org/10.1117/12.682637
Event: SPIE Optics + Photonics, 2006, San Diego, California, United States

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 (AOD_Lidar > 1, AOD_Cimel > 1 and AOD_MODIS > 0.39) occurred in April. AOD_MODIS shows significant underestimation. AOD_Lidar has good correlation with AOD_Cimel, 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 AOD_Cimel and surface PM_2.5 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.

Citation Download Citation

Yi-Wei Chen, Anupam Hazra, Wei-Nai Chen, M.-L. Lin, P.-H. Lin, Charles C.-K. Chou, and J.-P. Chen "Application of lidar in the observation of atmospheric particulate pollutants in Taipei", Proc. SPIE 6299, Remote Sensing of Aerosol and Chemical Gases, Model Simulation/Assimilation, and Applications to Air Quality, 62990E (1 September 2006); https://doi.org/10.1117/12.682637

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