Northern Hemisphere sees decreasing aerosol optical depth: research

BEIJING -- Chinese researchers have studied the long-term global distribution of Aerosol Optical Depth (AOD) that has great significance on air pollution control, forest fire prevention and climate research, and found that the AOD experienced a slight downward trend in the Northern Hemisphere during the past 20 years, according to a recent research article published in the journal Atmospheric Environment.

Using satellite data, the researchers from the Hefei Institutes of Physical Science under the Chinese Academy of Sciences and the Anhui University of Science and Technology analyzed the global spatial-temporal distribution and variation of the AOD at 550 nanometers (AOD550).

The results showed that the distribution of the AOD550 nm with latitude or longitude is closely related to the distribution of population and aerosol natural source.

The decreasing trend of AOD is particularly obvious in Southeast China, the article stated, adding that the annual mean AOD550 over the Northern Hemisphere is significantly higher than that of the Southern Hemisphere.

The AOD is crucial in characterizing the degree of atmospheric turbidity and an important factor to determine the climatic effect of aerosol. Higher AOD values usually indicate the growth of longitudinal accumulation of aerosol, resulting in reduced atmospheric visibility.