The Reduction of the Global Irradiance Due to the Asian Dust Aerosols (PM_(10)) Estimated by the Observed Data in the Dust Source Region of Erdene in Mongolia

摘要

An empirical method of the PM10 to reduce the global irradiance has been developed with the observed 14-day data in 2009 at the Erdene site in the Asian dust source region of Mongolia. The observed data at a 10-min interval are used to get all parameters for the estimation of the beam and diffuse irradiances except for the properties of Asian dust aerosols such as the single scattering albedo (omega(0)), scattering transmittance (tau(a)) and transmittance due to aerosol absorption (tau(aa)) using the parametric solar radiation model. To determine these parameters, firstly tau(a) is calculated with the observed global irradiance for a given omega(0) value using all sampled data. And then the estimated tau(a)s are correlated with observed dust concentration to find an optimal regression equation between tau(a) and the observed dust concentration. The optimal omega(0) value is found that the error between the calculated global irradiance using the optimal regression equation and the observed global irradiance becomes minimum. It is found that the single scattering albedo of Asian dust aerosol (omega(0)) is 0.85 and its reduction rate of the global irradiance is up 34.4% of that of the dust free atmosphere for the heavy dust case. This reduction is mainly contributed by the reduction of the beam irradiance whereas the diffuse irradiance enhances slightly (about 1.8%) the global irradiance. The presently developed optimal regression equation between tau(a) and the observed dust concentration has a great potential to estimate the impact of Asian dust aerosols on the solar irradiance.