Study on PM 2.5 Pollution Synoptic Patterns in Hubei Province and Its Connection with LargeScale Circulation in Winter Months
Based on the PM2.5 air quality monitoring data of Hubei Province in winter months during 2015-2016, the PM2.5 mass concentration is classified by EOF method and its synoptic patterns are analyzed. The correlation between PM2.5 and largescale circulation is discussed and correlation index with SLP is established. The results show that the PM2.5 mass concentration in central part of Hubei is higher than in the easten and westen parts. There are large fluctuations in the PM2.5 time series and a downward trend in the recent two years. Four distinguished modes of PM2.5 are clarified, which can explain over 86.2% of the variance. The synoptic patterns are transmission type and local accumulated type. The PM2.5 mass concentration of transmission type is higher than the other one. The transmission type presents pollution in the whole region, pollution in the west and pollution in the northcentral, respectively. Northerly airflow dominates Hubei during the whole region pollution, bringing PM2.5 from northern China. For the west region pollution of transmission type, the pollutions and moisture are carried to western Hubei by east winds and the western Hubei mountain makes the pollutions accumulate in this area. The northcentral region pollution shows a collection effect of northeast and northwest wind. The local accumulated type pollution in eastern Hubei and southcentral Hubei are under the common cause of static weather condition and terrain. The transporting paths of three transmission type pollution are the north path, east path and northeast path.With the decrease of highlevel East Asia trough and lowlevel cold continental high pressure, PM2.5 mass concentration increases. The correlation index with the sea level pressure is closely related to the PM2.5 mass concentration and the first EOF mode time coefficient which has certain significance for pollution forecasting.