2015年北京、上海和拉萨PM2.5浓度日变化和日际变化分析

分析2015年北京、上海和拉萨3个城市PM_2.5浓度的时间序列, 讨论PM_2.5浓度的季节变化以及各城市PM_2.5浓度日际变化与日变化的相对重要性。从长期来看, 3个城市冬季PM_2.5浓度普遍大于夏季; 从短期来看, 北京和上海PM_2.5浓度主要呈现日际变化, 天气系统的影响远大于日变化。北京冬季PM_2.5浓度在一定程度上也呈现日变化, 但在夏季不明显; 上海在冬季和夏季都不呈现日变化; 拉萨的情况则相反, 当地的天气系统比较稳定, 日际变化不明显,PM_2.5浓度主要受日变化影响,PM_2.5浓度的日变化呈现明显的“双峰”现象。

Interdiurnal and Diurnal Variation ofPM2.5 Concentration in Beijing,Shanghai, and Lhasa in 2015

The temporal variation ofPM_2.5 concentration in Beijing, Shanghai and Lhasa in 2015 is investigated. Then, the analyses on their seasonal variation and comparison of the relative importance of diurnal variation and daily variation are conducted. Results show that thePM_2.5 concentration is generally higher in winter than that in summer from a long-term view. From a short-term view, the variation ofPM_2.5 concentration in Beijing and Shanghai mainly demonstrates interdiurnal feature, and the synoptic systems exert profound impacts. The wintertime PM_2.5 concentration in Beijing also displays diurnal variation, but it is not evident in summer. In Shanghai, the diurnal cycle is not significant in both winter and summer. On the contrary, the synoptic system over Lhasa is stable. The daily variation is weak, while the diurnal variation is strong. The variation ofPM_2.5 concentration is hence featured by two peaks.