Characteristics and Meteorological Factors of Severe Haze Pollution in China

Table 6

Mean backward trajectory clusters frequency (%) and PM_2.5 mean concentrations (μg m⁻³) associated with the five trajectory clusters in seven Chinese cities. Bold numbers represent the mean PM_2.5 concentration of each trajectory cluster.

City	Cluster1 (C1)	Cluster2 (C2)	Cluster3 (C3)	Cluster4 (C4)	Cluster5 (C5)
Handan	12.50	72.92	8.33	4.17	2.08
	304.00	207.99	109.92	227.69	211.25
Zhengzhou	10.42	12.50	38.54	21.88	16.67
	255.14	270.89	208.07	330.65	205.90
Xi’an	19.79	12.50	35.42	15.63	16.67
	200.36	182.73	192.90	198.91	164.13
Yuncheng	5.21	17.71	35.42	37.50	4.17
	235.56	233.98	191.93	200.75	228.65
Chengdu	11.46	32.29	41.67	7.29	7.29
	112.90	119.31	120.79	98.50	135.93
Xiangyang	8.33	34.38	23.96	18.75	14.58
	198.17	208.89	192.95	261.73	261.04
Jinan	6.25	14.58	62.50	7.29	9.38
	162.11	183.07	189.33	143.35	191.00