The aerosol optical depth was affected by the chemical composition, the particle size and the shape of aerosol as well as
the water vapor in the atmosphere; it is an important indicator for air pollution. The special and temporal characteristics
of aerosol optical depth (AOD) was measured by CE318 sun-photometer, Angstrom wavelength exponent (Alpha) and
the aerosol turbidity coefficient (β) were calculated in Ningbo, Lin'an and Qiandaohu of Zhejiang province from 2007 to
2008. We also analyzed the relationship between AOD and Angstrom wavelength exponent (Alpha) in these stations.
The results show that there are different pattern of AOD in this gradient of urban and suburban region. Lin'an station had
two peaks of AOD, but Ningbo and Qiandaohu stations had single peak of AOD in measurement year. The difference of
AOD seasonal pattern exists in three sites. The Angstrom wavelength exponent (Alpha) analysis suggests that the aerosol
sizes in three stations various from fine particle in autumn to coarse particle in spring. The seasonal patterns show that
spring air pollution is serious, summer is relatively clean, and autumn and winter are relative serious in three stations.