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

Figure 5

Spatial distribution of the annual mean PM2.5 concentration from 2014 to 2017: (a) 2014; (b) 2015; (c) 2016; (d) 2017.

(a)

(b)

(c)

(d)