Satellite radar altimetry from open ocean to coasts: challenges and perspectives

The history of satellite radar altimetry stems from the need to capture a global view of the surface topography of the oceans. As altimeters are specifically designed for global observations, they encounter major problems in coastal regions, such as relatively poor sampling and inaccuracy of the corrections, so measurements are generally discarded. Nevertheless, a global archive of 15 years of raw data from a series of missions is presently available. The huge amount of unused data in coastal regions can be re-analyzed, improved and more intelligently exploited, possibly promoting coastal altimetry to the rank of operational service. This paper outlines the obstacles limiting the use of the data, discusses some areas of improvement, shows the lessons learned from a case-study in the Mediterranean Sea, and shows that the improved coastal altimetry concept can be extended to other regions, e.g. along the coasts of India. This paper also explores the implications of adopting the emerging vision of the Internet infrastructure in the coastal altimetry context: a collection of unstructured information becomes a network of linked data and software, necessary to perform the specialized on-the-fly processing of the raw data to provide ready-to-use geophysical parameters such as sea level and significant wave height.