SO<sub>2</sub> noontime-peak phenomenon in the North China Plain

Abstract

Abstract.A phenomenon of frequent noontime SO 2 concentration peaks was discovered in a detailed analysis of the SO 2 concentrations in the North China Plain (NCP). The possible causes and their contributions are analyzed. The impacts of such a phenomenon on the sulphur cycle were studied and the implications of the phenomenon for atmospheric chemistry, cloud physics, and climate were discussed. Different from the more common SO 2 diurnal patterns with high nighttime concentrations, NCP witnessed high frequencies of noontime SO 2 peaks, with an occurrence frequency of 50 to 72 % at four stations. Down mixing of elevated pollution layers, plume transport processes, mountain-valley winds, and fog/high RH haze events were the possible causes. The contribution of each process varies from day to day and from station to station, however, none of those four processes can be neglected. SO 2 peaks occurring during noontime instead of nighttime will lead to a 13 to 35 % increase in sulphur dry deposition, a 9 to 23 % increase in gas phase oxidation, and an 8 to 33 % increase in aqueous phase conversions, which will increase the hygroscopicity and the light scattering of aerosols, thus having important impacts on atmospheric chemistry, cloud physics, and climate.

Measurements of PM10 ions and trace gases with the online system MARGA at the research station Melpitz in Germany – A five-year study

“…Furthermore, for all seasons the highest concentrations occurred at noon, which is in agreement with the measurements performed by Henschel et al (2013). The SO 2 noontime peak was investigated by Xu et al (2014) for measurements performed in the North China Plain (NCP). The group tried to explain the peaks observed in the NCP with different reasons.…”

Retrieval of near-surface sulfur dioxide (SO<sub>2</sub>) concentrations at a global scale using IASI satellite observations

“…Such a diurnal cycle of SO 2 has been observed previously in China (Wang, 2002;Wang et al, 2014) and in other regions of the world (Khemani et al, 1987;Psiloglou et al, 2013), but in others, noontime SO 2 peaks have also been observed (e.g. Lin et al, 2012;Xu et al, 2014), possibly as a result of other meteorological/dynamical effects (Xu et al, 2014).…”

Analysis of Compositional Variation and Source Characteristics of Water-Soluble Ions in PM2.5 during Several Winter-Haze Pollution Episodes in Shenyang, China

“…2 , NO 2 , and CO), when the standard eigenvector > 1, the factor with the largest variance was chosen as the first group, and the process was repeated. If the variables differ greatly, the PCA results will also vary greatly because a covariance or correlation matrix is used [52]. Data are reliable when the value of KMO (Kaiser-Meyer-Olkin) is greater than 0.6.…”