The Tandem-L Mission Proposal: Monitoring Earth’s Dynamics with High Resolution SAR Interferometry

Tandem-L is a proposal for an innovative interferometric and polarimetric radar mission that enables the systematic monitoring of dynamic processes on the Earth surface. Important mission objectives are global forest height and biomass inventories, large scale measurements of millimetric displacements due to tectonic shifts, and systematic observations of glacier movements. The innovative mission concept and the high data acquisition capacity of Tandem-L provide a unique data source to observe, analyze and quantify the dynamics of a wide range of mutually interacting processes in the bio-, litho-, hydro- and cryosphere. By this, Tandem-L will be an essential step to advance our understanding of the Earth system and its intricate dynamics. This paper provides an overview of the Tandem-L mission concept and its main application areas. Performance predictions show the great potential of Tandem-L to acquire a wide range of bio- and geophysical parameters with high accuracy on a global scale. Innovative aspects like the employment of advanced digital beamforming techniques to improve performance and coverage are discussed in detail

Generation of Priority Research Questions to Inform Conservation Policy and Management at a National Level

Integrating knowledge from across the natural and social sciences is necessary to effectively address societal tradeoffs between human use of biological diversity and its preservation. Collaborative processes can change the ways decision makers think about scientific evidence, enhance levels of mutual trust and credibility, and advance the conservation policy discourse. Canada has responsibility for a large fraction of some major ecosystems, such as boreal forests, Arctic tundra, wetlands, and temperate and Arctic oceans. Stressors to biological diversity within these ecosystems arise from activities of the country's resource-based economy, as well as external drivers of environmental change. Effective management is complicated by incongruence between ecological and political boundaries and conflicting perspectives on social and economic goals. Many knowledge gaps about stressors and their management might be reduced through targeted, timely research. We identify 40 questions that, if addressed or answered, would advance research that has a high probability of supporting development of effective policies and management strategies for species, ecosystems, and ecological processes in Canada. A total of 396 candidate questions drawn from natural and social science disciplines were contributed by individuals with diverse organizational affiliations. These were collaboratively winnowed to 40 by our team of collaborators. The questions emphasize understanding ecosystems, the effects and mitigation of climate change, coordinating governance and management efforts across multiple jurisdictions, and examining relations between conservation policy and the social and economic well-being of Aboriginal peoples. The questions we identified provide potential links between evidence from the conservation sciences and formulation of policies for conservation and resource management. Our collaborative process of communication and engagement between scientists and decision makers for generating and prioritizing research questions at a national level could be a model for similar efforts beyond Canada

The Legacy of the SIR-C/X-SAR radar system: 25 years on

Twenty-five years ago, the two flights of the SIR-C/X-SAR Synthetic Aperture Radar (SAR) system on the Space Shuttle Endeavour blazed a trail toward the future with a series of radar system innovations - that nearly every spaceborne SAR flown since then has benefited from, and in some cases improved upon. Many of the SAR techniques adopted by SAR system designers worldwide as part of their toolkit, such as: ScanSAR, Spotlight mode, along-track interferometry, polarization diversity and polarimetry, polarimetric calibration, variable length and bandwidth pulses, and on-board processing, can trace their heritage back to this first-of-a-kind, civil-use SAR system. The electronic steering capability of SIR-C’s phased array antenna, combined with the exquisite orbit track control provided by the Space Shuttle, paved the way for systematic mapping of the Earth’s topography by the Shuttle Radar Topography Mission, and later by TanDEM-X. Some techniques, such as multi-frequency SAR, multi-frequency repeat-pass interferometry and onboard processing have yet to be fully exploited. The richness of the SIR-C/X-SAR data set has proved to be a treasure trove for opening up entirely new remote sensing techniques, such as Polarimetric SAR Interferometry (or PolInSAR), and GPS, now GNSS reflections (also known as Signals of Opportunity), which were both demonstrated from archive data, years after the 1994 flights. The ground-breaking legacy of SIR-C/X-SAR lives on in the many SAR systems collecting data in Earth orbit today, and in those planned for the future