This special issue deals with physical coastal oceanography, involving modelling, in situ observations, and satellite data. This is the aim of the H2020 CEASELESS project from which the papers stem. The aim of the special issue is to achieve, based on CMEMS products, a high-grade set of coastal oceanography predictions suitable for dealing with the increases in pressures and conflicting uses typical of the narrow land–water border.

The issue will tackle the enhanced resolution and prediction capabilities for meteorological and oceanographic variables at coastal scales that allow coupling and assimilation at an unprecedented level of resolution, including a new wealth of satellite data (with an emphasis on the Sentinel family). This is in line with new coastal zone products and requirements (e.g. wind profiles for renewable energy) and applications (e.g. coastal water quality for aquaculture or tourism) that prompt new advances in coastal oceanography such as the ones presented here. The papers included in this issue deal with the assimilation required by wave fields using new observational capabilities together with a synergy between satellite observations and wave model simulations during extreme events, the ones associated with higher levels of damage and therefore risks in coastal areas. There are also detailed analyses of the boundary layer between air and sea and how that affects wave simulations or the inter-comparison of different altimeter data sets and how they present distinctive features depending on their distance to the coast. This is followed by some applications of aforementioned results to coastal sediment transport and water quality properties plus the associated prediction limits in regional high-resolution modelling systems. The collection ends with a process-based definition of the coastal zone transitional area, with implications for nesting and downscaling as well as of the design of further observational campaigns. The issue is also open to other relevant submissions within the stated general scope.