Search

A multiscale analysis of meteorological trends was carried out to investigate the impacts of the large-scale circulation types as well as the local-scale key weather elements on the complex air pollutants, i.e., PM

The effect of vegetation seasonal cycle alterations to aerosol dry deposition on PM

A multiscale analysis of meteorological trends was carried out to investigate the impacts of the large-scale circulation types as well as the local-scale key weather elements on the complex air pollutants, i.e. PM

Based on laboratory studies and field observations, a new parameterization of uptake coefficients for heterogeneous reactions on multi-component aerosols is developed in this work. The equivalent ratio (ER) of inorganic aerosol is used to establish the quantitative relationship between the heterogeneous uptake coefficients and the composition of aerosols. Incorporating the new ER-dependent scheme, the WRF-CUACE model has been applied to simulate sulfate mass concentrations during December 2017 in the Beijing-Tianjin-Hebei region and evaluate the role of aerosol chemical components played in the sulfate formation. Simulated temporal variations and magnitudes of sulfate show good agreement with the observations by using this new scheme. From clean to polluted cases, although both dominant cations and anions increase significantly, the equivalent ratio decreases gradually and is closer to unity, representing the variation of aerosol compositions, which inhibits the heterogeneous uptake of SO2, with the uptake coefficient decreasing from 1 × 10-4 to 5.3 × 10-5. Based on this phenomenon, a self-limitation process for heterogeneous reactions with the increasing secondary inorganic aerosol from clean to polluted cases is proposed.

The impact of Arctic Oscillation (AO) anomalies on winter PM

Twenty-one years of observations (1980-2000) of weekly mean concentrations of major anthropogenic and natural metals in the aerosol of the lower Arctic troposphere at Alert have been analyzed by time series analysis for seasonal and long-term trends and by positive matrix factorization for major aerosol components with which metals are associated. Metals at Alert exhibit distinct seasonal variations depending on the source and origin of the metals. Anthropogenic metals such as Pb, Zn and Cu and the sea-salt components Na and Mg exhibit maxima in winter and minima in summer. Similar variations were observed for non-soil fractions of V and Mn. Weak seasonal variations were found for soil-related metals such as Al, Ba, Ca and Fe. If any trend is evident in anthropogenic metals, it is a slight decrease from 1980 to mid-1990s but generally the variation is not monotonic. It is found through the winter observations of Pb, Zn, Ni and Cu concentrations that the decline trends have been leveled off and started to increase again around 1995. No long-term trends were detected in Na, Mg and Ca concentrations but a slight decrease is observed for soil components Al, Fe and Ti after 1995. Analysis showed that these trends are mostly associated with the anthropogenic emission variations surrounding the Arctic regions.