Characteristics of Aerosol Optical Thickness as Well as the Relationship with NDVI in the Yangtze River Delta, China

Zhongyong Xiao,Jian Chen,Guomo Zhou,Hong Jiang,Renjian Zhang

doi:10.3319/tao.2013.05.02.01(a)

Abstract

A long term (2000 - 2008) dataset of aerosol products retrieved from MODerate Resolution Imaging Spectroradiometer (MODIS) is used to investigate the temporal and spatial variations of aerosol optical thickness (AOT) over the Yangtze River Delta (YRD). Ground-based observations (sun photometers) were used to validate the MODIS L2 aerosol products, and the Normalized Difference Vegetation Index (NDVI) derived from SPOT-VGT is used to analyze the relationship with AOT. The results illustrate that the highest correlation (R = 0.92) of CE-318 AOT vs. MODIS AOT is in Hangzhou with the slope and intercept of 1.04 and -0.01. The largest value of AOT appears in June, and has the largest spatial differences in July. There are two different aerosol patterns. One includes smaller AOT over dense vegetation cover areas dominated by natural aerosols and the other involves larger AOT over urban areas where anthropogenic aerosols dominate. The correlation analysis indicates that there are moderate negative correlation coefficients (R) for AOT vs. NDVI, and the R values vary as seasons shift. The range of R values is 0 ~ -0.8 and the mean values are about -0.5. The relationship between AOT and NDVI is more obvious in dense vegetation areas.

Highlights

Atmospheric aerosols play a significant role in human health and in the Earth’s climate
Many studies have been carried out to validate the MODerate Resolution Imaging Spectroradiometer (MODIS) aerosol products using ground-based sun photometer observations (Holben et al 1998, 2001; Chu et al 2002; Levy et al 2005, 2007, 2010; Remer et al 2005). Most of these validations have shown that MODIS aerosol optical thickness (AOT) values were within the ex
The results suggest that the change of land use and land cover (LULC) is the source of the Normalized Difference Vegetation Index (NDVI) variation, such as urbanization that results in decreasing agricultural land in this region

Summary

Introduction

Atmospheric aerosols play a significant role in human health and in the Earth’s climate. The net effect of aerosols is to cool the climate system by reflecting sunlight (Kaufman et al 2002). These effects are quite uncertain (IPCC 2001, 2007) due mainly to the complicated physical and chemical properties of aerosols, As a crucial step toward the understanding of the complex effects of aerosols in the atmosphere, aerosol properties and distribution should be quantified accurately. Several aerosol groundbased observational networks have been established to understand aerosol optical properties such as NASA’s Aerosol Robotic Network (AERONET) (Holben et al 1998, 2001). AERONET provides much information on the properties of aerosols for global or regional research. Recent instrument developments have offered new possibilities for measuring aerosol properties, such as the MODerate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Earth Observing

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Conclusion