The Sensitivity of the Current POLDER Land Aerosol Polarized Retrieval Algorithm to Particle Size
Author(s): WANG Jiacheng
Pages: 790-796
Year: 2014 Issue: 5
Journal: Geo-Information Science
Keyword: polarized remote sensing; aerosol; particle size;
Abstract: One of the polarized remote sensing advantages is its insensitivity to the land surface reflection, and now it has been widely used for aerosol properties retrieval from satellite and ground-based remote sensing. As to aerosols, the polarized remote sensing is only sensitive to small particles;however, there are different under-standings of the small particle size to which extend the polarized remote sensing is sensitive. For example, some studies take fine mode aerosols as small particles, but the maximum radius of fine mode aerosol varies between 0.4~1.0 μm . What’s the upper threshold of the particle size to which the polarized remote sensing is sensitive? In order to determine the sensitivity of the polarized remote sensing to aerosol particle size, three steps are con-ducted as follows: firstly, the POLDER (Polarization and Directionality of the Earth’s Reflectances, which is equipped on Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar) and AERONET (Aerosol Robotic Network) data in Hefei between 2007 and 2008 are collected and processed, i.e. the AERONET data within a 1-hour range window (±30min) around the POLDER during ze-nith pass and the POLDER data in a 3×3 pixel box centered on the Hefei site are averaged in time and space re-spectively. Secondly, the aerosol optical depths in different particle size range are calculated using the refractive index and size distribution data from Hefei site according to Mie theory. Finally, the particle size to which the po-larized remote sensing is sensitive is determined by finding the best fit between the POLDER aerosol optical depth and the AERONET aerosol optical depth calculated above. The results show that the polarized remote sens-ing is not sensitive to all the fine mode particles, but sensitive to particles with radius approximately less than 0.3μm at 865nm band. The results will not only help us to understand and utilize the aerosol products obtained from the polarized remote sensing, but also help us in polarized remote sensing application.
Pages: 790-796
Year: 2014 Issue: 5
Journal: Geo-Information Science
Keyword: polarized remote sensing; aerosol; particle size;
Abstract: One of the polarized remote sensing advantages is its insensitivity to the land surface reflection, and now it has been widely used for aerosol properties retrieval from satellite and ground-based remote sensing. As to aerosols, the polarized remote sensing is only sensitive to small particles;however, there are different under-standings of the small particle size to which extend the polarized remote sensing is sensitive. For example, some studies take fine mode aerosols as small particles, but the maximum radius of fine mode aerosol varies between 0.4~1.0 μm . What’s the upper threshold of the particle size to which the polarized remote sensing is sensitive? In order to determine the sensitivity of the polarized remote sensing to aerosol particle size, three steps are con-ducted as follows: firstly, the POLDER (Polarization and Directionality of the Earth’s Reflectances, which is equipped on Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a Lidar) and AERONET (Aerosol Robotic Network) data in Hefei between 2007 and 2008 are collected and processed, i.e. the AERONET data within a 1-hour range window (±30min) around the POLDER during ze-nith pass and the POLDER data in a 3×3 pixel box centered on the Hefei site are averaged in time and space re-spectively. Secondly, the aerosol optical depths in different particle size range are calculated using the refractive index and size distribution data from Hefei site according to Mie theory. Finally, the particle size to which the po-larized remote sensing is sensitive is determined by finding the best fit between the POLDER aerosol optical depth and the AERONET aerosol optical depth calculated above. The results show that the polarized remote sens-ing is not sensitive to all the fine mode particles, but sensitive to particles with radius approximately less than 0.3μm at 865nm band. The results will not only help us to understand and utilize the aerosol products obtained from the polarized remote sensing, but also help us in polarized remote sensing application.
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