Retrieval method for aerosol optical depth over Fuzhou based on MODIS data

Abstract

Aerosol optical depth (AOD) was an important factor in the aerosol research, the AOD over Fuzhou city was retrieved based on MODIS data of November 11th, 2006, and a test of sensitivity to AOD and the surface reflectance were made for the planetary albedo of three channels of MODIS (red channel, blue channel and mid-infrared channel) by 6S (second simulation of satellite signal in the solar spectrum) atmospheric radiation models. Based on Dense Dark Vegetation algorithms (DDV) advocated by Kaufman, which must be possessed with two basic rules that correlation of the AOD and planetary albedo of red band and blue band were sensitive, on the opposite, the AOD of mid-infrared band was no significant change with the planetary albedo of mid-infrared band. As a result, the sensitivity test was accord with the two basic rules of DDV. Furthermore, the AOD images of red, blue and mid-infrared bands were retrieved by DDV based on the MODIS data, Moreover the 550 nm AOD image and its isoline were made to analyze the characters of AOD and it was high correlation between the AOD and PM10 in Fuzhou city. The results showed that the there were tow high values areas in outline of AOD, one lied in Fuzhou metropolitan area, where was the commercial trade centre in Fuzhou. The other lied in Mawei development area where many factories and shipbuilding mills were in existence. However, the minimum of AOD mainly lied in high mountains such as Gushan and Qishan mountains, where owned dense vegetation and forest. In conclusion, the AOD layouts retrieved from MODIS data were agreed with the distribution of urban surface types in Fuzhou, and the export and transfer of aerosol grains was slow because of landform.