Measurement of aerosol optical depth in Qingdao by Sky radiometer

摘要

A high spectral resolution sky radiometer has been operated in Qingdao since April 2002 to measure aerosol radiative properties. Aerosol optical depth (AOD) was obtained on the basis of a procedure involving a Mie code and a radiative transfer code. AOD is strongly dependent on the weather condition and wind direction. The cloud-free daily average AOD at 500nm for fine, north wind, south wind, light fog, haze, fog and haze weather is 0.322, 0.465,0.798, 0.934, 0.467, 0.777, respectively. Water vapour is very crucial for the enhancement of AOD and the increase of volume concentration of fine particles. When the relative humidity is larger than 60%, 80% AOD tendes to be larger than 0.5, volume concentration of nucleus mode aerosol increases one order of magnitude, and the concentration of accumulation mode aerosol was also increased much. Dependence of AOD on wavelenght is analysed based on AngstrOEm power law relationship. AngstrOEm exponent is usually in the range of 0.9～1.4, and turbidity is often less than 0.3.