Assessing Spatiotemporal Characteristics of Urban PM2.5 Using Fractal Dimensions and Wavelet Analysis

Table 2

Boundary dimensions of PM2.5 concentration at each section line from 2014 to 2017 in Beijing.

Year	Section line	Regression equation	Boundary dimension	Coefficient of determination
2014	I	lnN = −1.1625lnδ + 5.9243	1.1625	0.99858
	II	lnN = −1.249lnδ + 6.2777	1.249	0.99744
	III	lnN = −1.2487lnδ + 6.386	1.2487	0.99949
2015	I	lnN = −1.0724lnδ + 5.7465	1.0724	0.99904
	II	lnN = −1.1945lnδ + 5.7843	1.1945	0.99597
	III	lnN = −1.1552lnδ + 5.8351	1.1552	0.99972
2016	I	lnN = −1.0892lnδ + 5.6857	1.0892	0.99862
	II	lnN = −1.1424lnδ + 5.8284	1.1424	0.99958
	III	lnN = −1.1976lnδ + 5.9991	1.1976	0.99722
2017	I	lnN = −1.0678lnδ + 5.6544	1.0678	0.99925
	II	lnN = −1.1343lnδ + 5.8918	1.1343	0.99492
	III	lnN = −1.1924lnδ + 6.1498	1.1924	0.99889