Study On The Relationship Between Aerosol Optical Depth And Air Pollution Index Based On PM₁0 In The Cities Of Hebei Plain Area

In recent years, atmospheric aerosols have become the main composition of the air pollution in many big and medium-sized cities. Although the environmental monitoring stations can monitor the concentration of aerosol particles, these sites cannot fully monitor the spatial distribution and time variation of atmospheric aerosols as they spread separately. Observation data on the MODIS satellite include abundant spatial-temporal changing information of optical character of aerosol. Using Aerosol Optical Depth (AOD) from MODIS satellite has special advantages, it can make up for the deficiency of ground-based observations.Air Pollution Index (API) is an important index for reflecting and evaluating air quality condition, which refers that several monitored pollutant concentrations are simplified into single conceptual number and classified to represent the air condition and level of pollution. This can present the public a more concise report of the air quality and it is convenient and helpful for people to know about the air quality condition and variety trend. In mainland China, most of the primary pollutants in most of urban cities are the inhalable particulate materials. Therefore, creating the quantitative model between AOD based on PM₁₀ and API is the essential link of using satellite remote sensing technology on monitoring atmospheric particulates pollution.This study is conducted based on the MODIS data of 8 cities in Hebei Plain Area from January, 2008 to December, 2009 and the daily air quality report data provided by environmental protection departments of Hebei Province. On the basis of dense dark vegetation algorithm and 6S radiative transfer model, the researcher has made an inversion of the aerosol optical depth over the cities of Hebei Plain Area on the support of ENVI 4.6 technology platform. Through the analysis of the spatial distribution and seasonal changes of aerosols and air pollution index based on PM₁₀, the different types of urban aerosol distribution are summarized. Further, the study focuses on the relationship between MODIS AOD and API when the primary pollutant is PM₁₀ in the 8 cities, and the linear regression models between aerosol optical depth and urban air pollution index are established. The correlation of the two indices will not be too high because of the physical differences. In order to improve the correlation of the two indices, the seasonal aerosol scalar and seasonal dummies are introduced to revise AOD so as to acquire more accurate quantitative models. At last, by contrasting the correlations and testing the confidence, it is found that after the introduction of seasonal dummy variable, the accuracy of models of AOD and API is significantly improved in each city of Hebei Plain Area. The result proves that using AOD monitored by satellite remote sensing technology to indicate the air quality of city is feasible.The innovations of the study are as follows:1. The quantitative model between AOD and API based on PM₁₀ in the cities of Hebei Plain Area is created.2. The accuracy of quantitative models is improved by introducing seasonal dummy variable to revise AOD.