Tao Jinhua

A method to estimate concentrations of surface-level particulate matter using satellite-based aerosol optical thickness

We propose a new method to estimate surface-level particulate matter (PM) concentrations by using satellite-retrieved Aerosol Optical Thickness (AOT). This method considers the distribution and variation of Planetary Boundary Layer (PBL) height and relative humidity (RH) at the regional scale. The method estimates surface-level particulate matter concentrations using the data simulated by an atmospheric boundary layer model RAMS and satellite-retrieved AOT. By incorporation MODIS AOT, PBL height and RH simulated by RAMS, this method is applied to estimate the surface-level PM2.5 concentrations in North China region. The result is evaluated by using 16 ground-based observations deployed in the research region, and the result shows a good agreement between estimated PM2.5 concentrations and observations, and the coefficient of determination R2 is 0.61 between the estimated PM2.5 concentrations and the observations. In addition, surface-level PM2.5 concentrations are also estimated by using MODIS AOT, ground-based LIDAR observations and RH measurements. A comparison between the two estimated PM2.5 concentrations shows that the new method proposed in this paper is better than the traditional method. The coefficient of determination R2 is improved from 0.32 to 0.62.

SO2 columns over China: Temporal and spatial variations using OMI and GOME-2 observations

Enhancements of SO2 column amounts due to anthropogenic emission sources over China were shown in this paper by using OMI and GOME-2 observations. The temporal and spatial variations of SO2 columns over China were analyzed for the time period 2005–2010. Beijing and Chongqing showed a high concentration in the SO2 columns, attributable to the use of coal for power generation in China and the characteristic of terrain and meteorology. The reduction of SO2 columns over Beijing and surrounding provinces in 2008 was observed by OMI, which confirms the effectiveness of strict controls on pollutant emissions and motor vehicle traffic before and during 2008 Olympic and Paralympic Games. The SO2 columns over China from GOME-2 (0.2–0.5 DU) were lower than those from OMI (0.6–1 DU), but both showed a decrease in SO2 columns over northern China since 2008 (except an increase in OMI SO2 in 2010).

Scattering properties of polluted dust in 1.6-μm wavelength

Three typical polluted dust particles (i.e., single coated dust, two-sphere/spheroid system, and coated dust with aggregate) including internal and semi-external mixtures are modeled, and their scattering properties at 1.6-μm wavelength are calculated by using the generalized multi-sphere Mie-solution (GMM) method. We investigate the influences of particle size, morphology, and chemical composition on the scattering parameters of polluted dust particles. The analysis results demonstrate that the single scattering albedo of coated dust is much smaller than that of pure dust, especially for the spheroidal black carbon (BC) coated dust. When a dust particle semi-mixes with another aerosol particle to form a two-sphere/spheroid system, its scattering properties are much more sensitive to the size and species of monomers than the monomer shape. If an aggregated BC attaches to the coated dust, the scattering properties of whole particle mainly depend on the host particle (coated dust).