The ALOS PALSAR Global Systematic Acquisition Strategy: 4 Years in Operation

With the launch of ALOS in 2006, JAXA took the initiative to implement the first global-scale systematic acquisition strategy for satellite sensors at fine (2.5m-20m) spatial resolution. Comprising all three sensors on ALOS (PALSAR, PRISM, AVNIR-2), the plan is designed to serve all ALOS user categories and aims at producing spatially and temporally consistent coverages over the planet on a repetitive basis, to accommodate systematic global-scale, fine-resolution, monitoring of the environment. Unlike the common background missions defined for most fineresolution Earth Observation satellites, the BOS has been implemented as a top-level foreground mission with a priority second only to that of special observation requests and emergency observations and sensor cal/val. Presently 4 years in operation, the strategy has produced a comprehensive and homogeneous global archive in which consistent time-series of data are available for any arbitrary point or region on Earth. Clouds and haze inevitably constitute limitations for the oprtical sensors, while for the PALSAR instrument, two cloud-free and near-gap free (~95%) global coverages are achieved annually. Previously, such uniform data archives existed only for coarse and midresolution sensors such as AVHRR, MERIS and MODIS.