Growth and Shrinkage of New Particles in the Atmosphere in Hong Kong

Figures & data

FIG. 1 Map of sampling sites.

TABLE 1 Summary of meteorological data from February 2003 to January 2004 (*January 2004, ** background air pollutant concentrations at the “Tap Mum” station).

	Mean temperature	Mean relative	Mean cloud	Total rainfall	PM10**	SO2
Month	(deg. C)	humidity (%)	coverage (%)	(mm)	(μ g m^–3)	(ppbV)
February	18.5	82	73	15.1	44	2.9
March	19.0	82	78	38.6	43	2.9
April	23.9	83	79	84.5	42	3.3
May	26.9	81	77	249.0	42	2.9
June	27.7	81	74	523.5	32	3.6
July	29.6	76	58	101.8	18	3.6
August	28.8	81	71	415.0	24	3.6
September	27.6	81	68	394.0	38	5.5
October	25.3	71	44	48.6	63	5.9
November	22.2	75	49	50.1	64	6.9
December	17.6	65	24	Trace	87	8.3
January*	15.8	73	67	51	63	6.2

TABLE 2 Occurrence of long-term ultrafine particle bursts (detailed definitions are given in the text).

	No. of scans	Regime 1 (< 10 nm to < 40 nm)	Regime 2 (< 20 nm to > 50 nm, < 50 nm)	Regime 3 (broad spectrum of particle size)	Regime 4 (No growth)
Oct. (31days)	8458	0	0	0	6
Nov. (29 days)	7632	2	1	1	4
Dec. (31 days)	7930	6	0	2	9
Jan. (30 days)	6643	3	1	0	5
Total occurrence		11	2	3	24

TABLE 3 Characteristics of Regimes1 and 2 new particle bursts.

Date	Type	Formation rate* (particle cm^–3 s^–1)	Growth rate (nm h^–1)	Duration (hr)
11 Nov. 2003	Regime 1	1.8	2.0	5
21 Nov. 2003	Regime 1	5.1	7.5	3
21 Nov. 2003	Regime 2	N/A**	8.5	2
3 Dec. 2003	Regime 1	11.5	3.2	8
12 Dec. 2003	Regime 1	4.7	4.1	6
13 Dec. 2003	Regime 1	2.3	2.2	8
14 Dec. 2003	Regime 1	4.4	5.2	4
16 Dec. 2003	Regime 1	2.7	3.7	6
19 Dec. 2003	Regime 1	3.9	5.0	8
12 Jan. 2004	Regime 2	4.3	11.8	4
21 Jan. 2004	Regime 1	2.7	3.4	5
24 Jan. 2004	Regime 1	2.4	3.0	5
25 Jan. 2004	Regime 1	3.2	2.1	10
;

FIG. 2 (a–e) Concentrations of particles and gases on 25 January 2004.

FIG. 3 (a–d) Temporal variation of ultrafine particles and size distributions on 25 January 2004 (a: dN_{< 30nm}/dt = 2.8 cm^–3 s^–1 and the average of Fcoag = 0.4 cm^–3 s^–1 during the initial 2 h of particle burst, A-10:25-10:40, B-15:20-15:40, C-19:15-19:45; c: GMD, geometric mean diameter; GR = 3.2 nm h^–1 during the initial 5 h).

FIG. 4 (a–e) Concentrations of particle and gases on 21 January 2004.

FIG. 5 (a–c) Particle growth followed by particle shrinkage on 12 January 2004 (GMD, geometric mean diameter).

FIG. 6 (a–d) Spatial distribution of air pollutants on 12 January 2004.

FIG. 7 (a–c) Particle growth followed by particle shrinkage on 21 November 2003 (GMD, geometric mean diameter).

FIG. 8 (a–d) Spatial distribution of air pollutants on 21 November 2003.

Qian , S. , Sakurai , H. and McMurry , P. H. 2007 . Characteristics of Regional Nucleation Events in Urban East St. Louis . Atmos. Environ. , 41 : 4119 – 4127 .

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