Study on the Precursor Signal Capturing of Unfavorable Weather: Months/Years in Advance to Ultra-Early Forecast for Hourly Transient Weather Changes during the Beijing Winter Olympics

Table 5

Statistical analysis of the impact of meteorological conditions on air quality every 5 days during the same period of the Beijing for the years 2017 to 2021.

Year	Date	1 to 5	6 to 10	11 to 15	16 to 20	21 to 25	26 to 29
2017	Visibility	3.1 km	3.3 km	2.1 km	2.2 km	3.3 km	2.2 km
	Weather phenomenon	Haze	Haze	Haze	Haze	Haze	Haze
	PLAM	182	79	183	115	190	115
	PM2.5	351	114	275	176	141	98
2018	Visibility	6.2 km	4.2 km	25.9	2.3 km	30.2 km	3.2 k
	Weather phenomenon		Haze		Haze		Haze
	PLAM	32	32	47	187	47	185
	PM2.5	51	99	79	250	64	227
2019	Visibility	1.2 km	30.4 km	1.1 km	1.3 km	1.2 km	3.2 km
	Weather phenomenon	Haze	Clear	Haze	Haze	Haze	Haze
	PLAM	189	9.3	190	188	193	90
	PM2.5	278	61	88	37	259	114
2020	Visibility	2.4 km	11 km	1.2 km	33.9 km	1.2 km	1.3 km
	Weather phenomenon	Haze	Haze	Haze	Clear	Haze	Haze
	PLAM	89	189	183	12	186	186
	PM2.5	59	193	268	32	146	161
2021	Visibility	14.6 km	5.6 km	1.3 km	30.5 km	31.2 km	9.4 km
	Weather phenomenon	Clear	Haze	Haze	Clear	Clear	Haze
	PLAM	10	18	190	11	13	185
	PM2.5	56	124	472	38	80	198 μg/m^3
Contribution (%)	Fine (baby blue)	56%	44%	20%	50%	40%	12%
	Weather (%)
	Unfavorable	44%	56%	80%	50%	60%	84%
	Meteorological conditions (%) (brown)