Estimation of gridded population and GDP scenarios with spatially explicit statistical downscaling

This study downscales the population and gross domestic product (GDP) scenarios given under Shared Socioeconomic Pathways (SSPs) into 0.5-degree grids. Our downscale approach has the following features: (i) it explicitly considers spatial and socioeconomic interactions among cities; (ii) it utilizes auxiliary variables, including, road network and land cover; (iii) it endogenously estimates influence from each factor by a model ensemble approach; (iv) it allows us controlling urban shrinkage/dispersion depending on SSPs. It is confirmed that our downscaling results are consistent with scenario assumptions (e.g., concentration in SSP1 and dispersion in SSP3). Besides, while existing grid-level scenario tends to have overly-smoothed population distributions in non-urban areas, ours does not suffer from the problem, and captures difference in urban and non-urban areas in a more reasonable manner.