摘要:基于2013~2016年空气质量监测台站资料，利用经验正交分解、功率谱分析、BP典型相关分析等多元数据分析方法解析了中国地区细颗粒物（PM2.5）主要模态的时空特征，并与排放源和气象场建立了相关关系，得到以下结论：中国地区PM2.5场存在两个主要模态，其中第一主模态为一致增加模态，强度中心位于西北地区东部—华北南部地区；其时间序列呈显著下降趋势。第二主模态主要表现为南北反向变化的偶极子型分布，其大值区分别位于华北中南部和长江中下游地区。其中，PM2.5第一模态可以看作平均态，主要受平均排放场和环流场及大地形的影响，在北方的表现更为显著。PM2.5第二模态可看作偏离平均场的一种变化态，在冬季更可能和冷空气活动有关。冷空气的强弱决定了污染累积的位置以及输送的方式，其作用是使得南方的污染明显偏离平均态，故第二主模态在南方的表现更为显著。本研究有效地利用了多元数据分析方法研究了我国大气污染的演变机理，可为进一步认清大气污染的形成规律提供科技支撑。
关键词:细颗粒物(PM2.5)/
主模态/
多元数据分析/
排放场/
气象场
Abstract:Based on 2013-2016 air quality monitoring station data, spatial and temporal characteristics of main modes of PM2.5 in China are analyzed using multivariate data analysis methods including empirical orthogonal decomposition, power spectral analysis and BP canonical correlation analysis. Their correlations with emission and meteorological fields are established. Major conclusions are as follows. There exist two main modes in the PM2.5 field in China. The first is an uniformly increasing mode with the large center located in eastern part of Northwest China and southern part of North China; its time series shows a significant downward trend. The second mode exhibits a dipole distribution with opposite changes in the north and south; the two large centers are located in the central and southern portions of North China and the middle and lower reaches of the Yangtze River, respectively. The first mode of PM2.5 can be regarded as the average state, which is mainly affected by the average emission field, the circulation field and large topography. Impacts of these factors are more significant in the north. The second mode can be regarded as a deviation from the average field, which is more likely associated with cold air activities in the winter. The strength of the cold air determines the location of accumulation of pollutants and the way of transport. Impacts of cold air activities often result in large deviations of pollutants from their averages in the south, and thereby the second mode is more significant in the south. This research effectively utilizes various multivariate data analysis methods to study the evolution mechanism of air pollution in China, which provides scientific and technological supports for further understanding the formation mechanisms for air pollution.
Key words:PM2.5/
Main mode/
Multivariate data analysis/
Emission field/
Meteorological field
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