Influence of Sea-Land Breezes on the Tempospatial Distribution of Atmospheric Aerosols over Coastal Region

Figures & data

Figure 1. Location of inland and offshore sampling sites in the coastal region of southern Taiwan.

Table 1. Concentrations of PM_2.5, PM_2.5–10, PM₁₀, and PM_2.5/PM₁₀ at the sampling sites in the coastal region of southern Taiwan during the intensive sampling periods

Sampling Sites	Periods	Number of Samples	PM2.5 (μg/m^3)	PM2.5–10 (μg/m^3)	PM10 (μg/m^3)	PM2.5/PM10 (%)
NKU	Daytime	6	50.52 ± 21.78	40.27 ± 20.28	90.79 ± 41.12	55.72 ± 4.15
	Nighttime	6	36.05 ± 19.94	32.17 ± 18.58	68.21 ± 38.49	53.14 ± 1.44
FYC	Daytime	6	43.89 ± 20.32	36.28 ± 14.58	80.17 ± 34.68	54.14 ± 2.68
	Nighttime	6	42.67 ± 26.26	29.63 ± 13.98	72.30 ± 38.84	57.36 ± 6.76
OSB	Daytime	6	34.97 ± 10.16	36.90 ± 17.59	71.87 ± 26.93	49.73 ± 4.94
	Nighttime	6	29.43 ± 8.35	33.68 ± 11.76	63.11 ± 20.10	46.96 ± 1.38
HLC	Daytime	6	25.76 ± 6.42	29.79 ± 13.22	55.55 ± 19.48	47.46 ± 4.22
	Nighttime	6	26.97 ± 6.91	33.02 ± 10.82	60.00 ± 17.37	45.36 ± 3.71
Notes: mean ± SD.

Figure 2. Variation of the size distribution of atmospheric aerosols measured at the (b, d, f) offshore and (a, c, e) inland sites of southern Taiwan during the SLBs periods: (a, b) first, (c, d) second, and (e, f) third sampling period.

Figure 3. Variation in PM₁₀ concentration with wind speed over the coastal region of southern Taiwan during the intensive sampling periods for the (a) HLC, (b) NKU, and (c) FYC sites.

Figure 4. Hourly variation of wind direction over the coastal region of southern Taiwan during the intensive sampling periods: (a) August 16–18, 2006; (b) November 2–4, 2006; and (c) May 2–4, 2007.

Figure 7. Variations in surface wind field simulated by MM5 over the coastal region of southern Taiwan during the intensive sampling periods: (a) August 16 at 2:00 p.m., (b) August 17 at 2:00 a.m., (c) August 17 at 2:00 p.m., (d) August 18 at 2:00 a.m. (e) November 2 at 2:00 p.m., (f) November 3 at 2:00 a.m., (g) November 3 at 2:00 p.m., (h) November 4 at 2:00 a.m. (i) May 2 at 2:00 p.m., (j) May 3 at 2:00 a.m., (k) May 3 at 2:00 p.m., and (l) May 4 at 2:00 a.m.

Figure 5. PM₁₀ concentration contour over the coastal region of southern Taiwan during the intensive sampling periods (x- and y-axis legends are UTM [Universal Transverse Mercator] units in kilometers): (a) August 16 at 2:00 p.m., (b) August 17 at 2:00 a.m., (c) August 17 at 2:00 p.m., (d) August 18 at 2:00 a.m. (e) November 3 at 2:00 p.m., (f) November 4 at 2:00 a.m., (g) November 3 at 2:00 p.m., (h) November 4 at 2:00 a.m. (i) May 2 at 2:00 p.m., (j) May 3 at 2:00 a.m., (k) May 3 at 2:00 p.m., and (l) May 4 at 2:00 a.m.

Table 2. Results of the paired t test for comparing the daytime and nighttime PM₁₀ concentrations at inland and offshore sites

	P
t test	August 16–18, 2006	November 2–4, 2006	May 2–4, 2007
Inland
NKU	4.20 × 10^−1	7.90 × 10^−6	2.23 × 10^−4
FYC	7.07 × 10^−3	4.14 × 10^−5	2.86 × 10^−3
Offshore
OSB	7.70 × 10^−3	7.81 × 10^−2	1.00 × 10^−1
HLC	5.00 × 10^−1	2.90 × 10^−2	2.59 × 10^−2

Figure 6. Backward trajectories of air parcels transported to the inland sampling sites over the coastal region of southern Taiwan during the intensive sampling periods (x- and y-axis legends are UTM in kilometers): (a) August 16–18, 2006; (b) November 2–4, 2006; and (c) May 2–4, 2007.

Figure 8. The vertical wind field profile in the coastal region of southern Taiwan on August 16 at (a) 2:00 p.m. and (b) 8:00 p.m.

Table 3. Correlation coefficients of the model simulation and the measurement at inland and offshore sites during the sampling periods

R	August 16–18, 2006	November 2–4, 2006	May 2–4, 2007
Inland	0.66	0.74	0.69
Offshore	0.63	0.69	0.67

Figure 9. Spatial distribution of PM₁₀ concentration simulated by CAMx over the coastal region of southern Taiwan during the intensive sampling periods (x- and y-axis legends are UTM in kilometers): (a) August 16 at 2:00 p.m., (b) August 17 at 2:00 a.m., (c) August 17 at 2:00 p.m., (d) August 18 at 2:00 a.m. (e) November 2 at 2:00 p.m., (f) November 3 at 2:00 a.m., (g) November 3 at 2:00 p.m., (h) November 4 at 2:00 a.m. (i) May 2 at 2:00 p.m., (j) May 3 at 2:00 a.m., (k) May 3 at 2:00 p.m., and (l) May 4 at 2:00 a.m.

Figure 10. Comparisons of hourly surface PM₁₀ concentrations at inland and offshore sites during the sampling periods: August 16–18, 2006 (a) offshore and (b) inland; November 2–4, 2006 (c) offshore and (d) inland; and May 2–4, 2007 (e) offshore and (f) inland.