Analysis of SO₂ Pollution Changes of Beijing-Tianjin-Hebei Region over China Based on OMI Observations from 2006 to 2017

Figure 4

Long trend of SO₂ (DU) over Beijing-Tianjin-Hebei region. (a) Annual average, (b) spring average, (c) summer average, (d) autumn average, and (e) winter average.

(a)

(b)

(c)

(d)

(e)