Fig. 1. Scatter diagram between C3S and Hefei

Fig. 2. Distribution diagram of methane mean concentration in China from 2003 to 2018

Fig. 3. Annual average methane concentration change and Methane concentration monthly mean from 2003 to 2018 in China

Fig. 4. The seasonal histogram and the monthly average of methane concentration from 2003 to 2018 in China

Fig. 5. Diagram of methane seasonal mean concentration in China from 2003 to 2018

Fig. 6. Distribution of monthly average methane concentration in China from 2003 to 2018

Fig. 7. Six regional regions of the country

Fig. 8. The variation diagram of curves of monthly mean methane concentration in six regions from 2003 to 2018

Fig. 9. Tendenly diagram of average methane concentration in six regions from 2003 to 2018 in China