Dust Aerosol Scattering Coefficient under Three Types of Sand Storm in Eastern Inner Mongolia in the Spring and Its Correlations with PM10 and Visibility

Dust aerosol scattering coefficient was measured using an integrating nephelometer deployed at the Xilinhot observatory and Dongsheng observatory in the spring (March to May) of 2004 to 2006. The mass concentration of PM10 and the visibility were also measured at the same time. We analyzed the variation features of the dust aerosol scattering coefficient in terms of atmospheric background, sand-blowing, dust storm, and strong dust storm. We discussed the diurnal variation of the dust aerosol scattering coefficient, the mass concentration of PM10 and the visibility under different intensities of sand storm. We also analyzed the correlation coefficient between the scattering coefficient and the mass concentration of PM10, and the correlation coefficient between the scattering coefficient and the visibility under different intensities of sand storm. Results show that the scattering coefficient can well reflect the intensity of sand and dust weathers. With the increase in dust storm intensity, the diurnal variation of the scattering coefficient varies from a bimodal distribution to a unimodal distribution. When the dust weather intensity is relatively weak, diurnal variations of the scattering coefficient and PM10 concentration are different. However, there exist certain similarities between their diurnal variations when a strong dust storm occurs. The diurnal variations of the scattering coefficient and the visibility are opposite to each other. There is a positive correlation between the scattering coefficient and the mass concentration of PM10, and the correlation enhances with increases in the dust weather intensity. The correlation coefficients under conditions of atmospheric background, sand-blowing, dust storm, and strong dust storm are 0.201, 0.809, 0.898, and 0.953, respectively. There is an exponential relation between the scattering coefficient and the visibility and the correlation between them enhances with increases in the dust weather intensity. Their correlation coefficients under conditions of atmospheric background, sand-blowing, dust storm, and strong dust storm are -0.773, -0.870, -0.918 and -0.940, respectively.