Visual Range Trends in the Yangtze River Delta Region of China, 1981–2005

Figures & data

Figure 1. Locations of (a) the YRDR and (b) its 20 sites. Area in the small box of panel a is the YRDR.

Table 1. The worst 20% and 50% and best 20% 25-yr average VR and their rates in the YRDR

		Worst 20% VR		50% VR		Best 20% VR
Population	Site	VR (km)	Rate (km/decade)	VR (km)	Rate (km/decade)	VR (km)	Rate (km/decade)
<500,000 (town)	Chengsi	13.7 ± 1.4	−1.6	25.7 ± 2.9	−3.1	40.5 ± 3.6	−2.5
	Lvsi	22.4 ± 0.8	0.1 ^a	29.8 ± 1.5	−0.2 ^a	37.2 ± 2.5	−0.6 ^a
	Shipu	13.7 ± 1.3	−1.5	21.8 ± 2.7	−3.0	35.5 ± 1.8	−1.6
	Longquan	20.9 ± 1.8	−0.6	28.6 ± 1.1	−1.0	36.1 ± 1.1	−1.4
	Pinghu	14.4 ± 1.1	0.1 ^a	23.8 ± 1.6	1.0	33.6 ± 0.7	0.5 ^a
	Quzhou	8.5 ± 2.3	−0.1 ^a	15.2 ± 2.0	−1.5	25.6 ± 4.5	−5.1
	Average	15.6 ± 5.1	−0.6	24.2 ± 5.0	−1.3	34.8 ± 5.3	−1.8
<1,500,000 (county-level city)	Dinghai	12.8 ± 1.3	−1.6	20.4 ± 2.0	−2.0	34.1 ± 1.5	0.4 ^a
	Chengzhou	13.0 ± 0.9	−0.4 ^a	19.5 ± 2.2	−0.9 ^a	32.8 ± 3.2	−0.9 ^a
	Xuyi	15.3 ± 3.0	−2.7	22.9 ± 5.0	−5.3	31.1 ± 6.1	−7.0
	Yinxian	13.4 ± 1.1	−0.7 ^a	19.2 ± 2.7	−2.0	30.3 ± 5.1	−5.8
	Dongshan	11.0 ± 1.6	−1.9	16.5 ± 2.0	−2.4	25.3 ± 5.2	−6.2
	Liyang	11.1 ± 1.4	−0.1 ^a	16.7 ± 1.9	−1.8	25.7 ± 5.7	−6.0
	Gaoyou	19.2 ± 2.1	−0.7 ^a	27.6 ± 1.0	−0.6 ^a	35.5 ± 1.0	−0.9
	Dongtai	22.1 ± 1.8	−1.8	28.9 ± 1.0	−1.0	35.5 ± 0.4	−0.4
	Jinhua	12.1 ± 0.3	0.1 ^a	16.1 ± 0.6	−0.2 ^a	21.9 ± 3.0	−2.1
	Nantong	18.5 ± 3.4	−2.7	26.6 ± 2.6	−2.3	34.8 ± 1.2	−1.2
	Average	14.9 ± 3.8	−1.3	21.4 ± 4.8	−1.9	30.7 ± 4.8	−3.0
>1,500,000 (prefecture-Level city)	Hongjia	14.6 ± 2.9	−3.7	22.8 ± 4.3	−5.7	34.1 ± 3.0	−3.7
	Changzhou	16.5 ± 5.0	−6.1	23.3 ± 6.2	−7.5	30.3 ± 7.5	−8.7
	Nanjing	8.5 ± 2.6	−3.2	16.5 ± 4.3	−5.6	26.6 ± 7.0	−9.2
	Hangzhou	7.8 ± 2.1	−2.5	15.1 ± 3.0	−3.5	26.4 ± 5.7	−6.8
	Average	11.9 ± 4.4	−3.9	19.4 ± 4.2	−5.6	29.4 ± 3.2	−7.1
Domain	Average	14.5 ± 4.3	−1.6	21.9 ± 4.9	−2.4	31.6 ± 4.9	−3.5
Notes: VR denotes the 25-yr average VR value. ^aThe station rejected the t test at the confidence level of 0.01.

Figure 2. The worst 20% and 50% and best 20% domain-average VR trends of the YRDR. Dashed lines are the linear regression curves of the corresponding trend lines.

Figure 3. Spatial distribution of the 5-yr average median (i.e., 50%) VR (in km): (a) the first 5 yr (i.e., from 1981 to 1985) and (b) the last 5 yr (i.e., from 2001 to 2005). The interpolation error created by sparse sites in southwestern Liyang and the coastal and southeastern regions of Longquan should be considered in analysis.

Figure 4. Ridit plot for Nanjing, Hangzhou, and Lvsi. A mean ridit value of 0.5 means there is no difference with respect to the reference distribution, whereas a ridit value <0.5 means lower VR and >0.5 means better VR.

Figure 5. Five-year averaged VR of the (a) worst 20%, (b) 50% (median), and (c) best 20% at Nanjing, Hangzhou, and Lvsi.

Figure 6. Total industrial output values of Jiangsu, Shanghai, and Zhejiang and energy consumption values in industrial enterprises of Jiangsu.