The Influence of Climate Factors, Meteorological Conditions, and Boundary-Layer Structure on Severe Haze Pollution in the Beijing-Tianjin-Hebei Region during January 2013

Table 2

Summary of meteorological factors in January 2013 in different air quality levels over the BTH region.

	Air quality levels		Pressure (hPa)	Wind speed (m/s)	Temperature (°C)	RH (%)	Sunshine hour (h)	Visibility (km)
All sites	I&II	Mean	1002.9	3.4	−11.8	41.5	7.9
		SD	46.8	2.3	5.4	11.5	0.6
	III&IV	Mean	997.5	2.1	−7.4	64.8	5.6
		SD	45.7	1.2	4.7	16.6	3.3
	V&VI	Mean	994.7	1.7	−5.7	76	3.1
		SD	45.4	0.9	3.4	13.7	3.5
Plain sites	I&II	Mean	1031.2	3.1	−9	40	8	20.3
		SD	9.6	2.3	3.2	11	0.7	6.1
	III&IV	Mean	1025.7	1.9	−5.5	68.5	5.1	10.8
		SD	5.6	1.1	3.1	16.3	3.3	4.9
	V&VI	Mean	1022.8	1.8	−4.2	82.1	1.4	4.3
		SD	4.7	0.9	2	11	2.5	3.3

SD represents standard deviation.