Toward an International StormWatch Using Wide Swath SAR

12 Wide swath synthetic aperture radar (SAR), exemplified by the multibeam ScanSAR modes of Radarsat, can potentially deliver global near–real-time coastal wind fields with nearly 2 orders of magnitude greater spatial resolution ( 300 m) than conventional (active or passive) scatterometers ( 25 km). But this superior resolution comes with caveats. An understanding of the small-scale ocean scattering physics, necessary to fully describe the complex relationship between wind and radar backscatter, remains incomplete. End-to-end calibration of multibeam SARs is difficult and still largely undemonstrated. And methods for nesting the intrinsically highresolution SAR wind estimates within those of the coarser numerical models, scatterometers, radiometers, and surface buoys are still in their infancy. Despite these caveats, ScanSAR offers a unique new tool for probing the wind field over the ocean. To illustrate, one especially compelling example from a Radarsat ScanSAR pass over the U.S. East Coast is described. (