This book presents recent advances in the area of Radioscience, Equatorial Atmospheric Science and Environment from the international symposium for equatorial atmosphere of the celebration of the Equatorial Atmosphere Radar (EAR) 20th Anniversary, conducted by Indonesian National Institute of Aeronautics and Space (LAPAN) and Kyoto University, in 2021. It provides a scientific platform for all participants to discuss ideas and current issues as well as to design solutions in the areas of atmospheric science, environmental science, space science, and related fields.