Seasonal cycles, interannual trends and spatial distributions of ozone in eastern North America. Each curve or map represents a smooth component, i.e. f1: seasonal cycle, f2: interannual trend and f3: spatial distribution, in the GAMM. The results are obtained from monthly mean of daytime average (blue) and DMA8 (red). The white points indicate the locations of stations. DOI: https://doi.org/10.1525/elementa.243.f3