Retrieval Of Aerosol Optical Depth Based On The Ground-based Measeurement Using Modis Data

Atmospheric aerosol plays an important role on the Earth's global climate system, and affecting the radiance budget and cloud processes of the atmosphere. When located near the surface, high concentrations lead to lowered visibility, increased health problems and generally reduced quality of life for the human population. So it is very necessary to carry on research to atmospheric aerosol.Unlike greenhouse gases, aerosols are not well mixed in the atmosphere. They are spatially and temporally inhomogeneous, and usually concentrated near earth's surface. Depending on their source, their size, and their physical properties, aerosols significantly influence the atmospheric transmittance. Since the MODIS over-land retrieval suffers from surface and other contaminations, it is not sufficiently sensitive to aerosol distribution within each size range. Therefore, the algorithm must select the aerosol model apriority of the retrieval. Based on summing up domestic and aerosol satellite remote sensing inversion algorithm, this paper selects mature, stable dark pixel method, uses MODIS data and the radiative transfer model and theory, the main work are summarized as follows:(1) Based on the character that the atmospheric aerosol optical thickness effects at 2.12um band of atmospheric radiative transfer is smaller, and there is a linear relationship between the surface reflectance in two visible channels (red and blue) and one shortwave infrared channel, this paper performs a simultaneous linear invention of reflectance in two visible channels (red and blue) and one shortwave infrared channel. The relationship is decided by the scattering angle and NDVISWir.(2) Through analyzing the meteoric characteristic of cloud in different spectrum and integrating the spectrum characteristic of MODIS, a cloud detection method was put forward which based on multi-spectrum synthesis.(3) According to CE318 data from Guangdong aerial remote sensing experiment, the author retrieval the physical characteristic of atmospheric aerosols in Zhongshan district, and self-define aerosol model of Zhongshan district. (4) Based on AERONET site data retrieval the aerosol size distribution and refractive index of Beijing monthly from 2005 to 2007, definition the average aerosol model every month.(5) There are four kinds of aerosol model applied to retrieval the aerosol optical thickness. The 4 days MODIS results at the Pearl River Delta region, indicate the aerosol model plays an importance role in the aerosol retrieval. Quality assessment with extensive experimental remote sensing satellite ground measurement data, and illuminating the distribution of AOD at the Pearl River Delta region.(6) Using three-year of 2005-2007 MODIS data in Beijing-Tianjin-Tangshan region, aerosol optical thickness retrieval was studied. Quality assessment of 3 years satellite results with NASA's AERONET and the Chinese sun hazemeter network data, to prove the stability and applicability of this algorithm.