Long-Term Pantropical Forest Monitoring with ALOS-2 L-Band SAR

Seven years in orbit ALOS-2/PALSAR-2 has provided the world’s first long-term pantropical L-band forest observation archive. In the frame of the JICA-JAXA forest early warning system in the tropics (JJ-FAST), Japan’s SAR earth observation excellence has pioneered for a seamless and timely monitoring of the tropical forest belt from 2016 to 2021. In this paper, we discuss the tremendous contributions to fundamental SAR forest research, forest mapping, biomass estimation, and operational deforestation detection and demonstrate the merits of the unprecedented dense forest time-series for the entire tropical forest belt. As preparation for the coming “golden-age of L-band SAR”, we show examples of how ancillary precipitation information and machine learning can improve the monitoring and protection of tropical forests.