The aerosol type and the concentration variation are the hotspots related to the climate change, the environment and the human-health. The AQUA/MODIS aerosol optical depth (AOD) product issued by NASA is used to analyze the temporal and spatial changes of the multi-yearly and annual mean AODs in the whole world and in China for diagnosing the aerosol events that directly emitted or affected, such as the haze, the dust storm or the volcano eruption. The results show that the eastern Asia, the Indian peninsula, the northern and central Africa and their adjacent ocean areas have relatively high AODs. The significantly changing areas include the east area of Siberia due to the smoke by fire and the Amazon rainforest for bioaerosols by vegetation emissions. These high and sensitive AOD regions are closely related with the aerosol emission by natural and human activities, and they are also influenced by weather and terrain. In China, the regions in the eastern China with the yearly mean AOD higher than 0.5 are the haze weather areas. In particular, the Huanghe-Huaihe River basin, the Yangtze-Huaihe River basin and the central part of China have the highest mean AODs of 0.8-1.0, where serious haze weather often occurs. The highest AOD is caused by the highest emission from the industrial and agricultural productions, constructions, and heavy transportations. So, based on the reference the AOD (background 0.2, natural events impact 0.15, human living impact 0.15) obtained from the aerosol distinctive area, the annual mean AOD of 0.5 is defined as a threshold for delimiting the haze area and the pollution control district. In China, the environmental improvement depends on the cutting back the industrial emissions in the regions with annual mean AOD higher than 0.5, and the middle cutting ratio is 33% and the averaged cutting ratio is 26.5%.

atmospheric aerosol  /  AOD  /  haze  /  MODIS