Foreword to the special issue on earth observation approaches for large area land monitoring with multiple sensors and resolutions

The papers in this special issue represent a wide range of current research efforts by the scientific community of Earth Observation (EO) data processing and monitoring algorithm developers and end-users of such datasets to address these issues. In particular, these papers reflect research that is designed to exploit information at multiple scales and sensor systems for analysis of local, regional and global EO data. The following situations are represented in this special issue: (1) large-area land mapping and monitoring approaches and applications; (2) using and analyzing data from multiple spatial, temporal and spectral resolutions in synergy; and (3) different surface types, ground-characteristics (e.g., land types: urban, vegetation, biophysical variables, etc.) and applications, including issues of consistency and continuity for applications. The special issue is comprised of papers representing three sensing paradigms: single sensor passive EO data, single sensor active EO data, and multi-sensor configurations that seek synergistic combinations of more than one EO for analysis. The special issue also includes papers that focus on the theory of effective exploitation of these modalities in single and multisensor configurations.