Fig. 1

Location map of stations in the MeSO-net in the Tokyo metropolitan area. a Map of Kanto region of Japan. Triangles show MeSO-net stations. Blue triangles are the MeSO-net stations considered in this study. b Close-up map in the middle of the Tokyo metropolitan area. Red, green, and black triangles show the type of noise reduction observed in this study. Purple squares are train stations for which population data are presented in Fig. 3