Coastal zones are the marine areas concentrating the greatest challenges, with the highest stakes –ecological and economical among others. But the ocean dynamics there is complex and rapid, with land and water more or less intertwined, bathymetry sometimes inducing resonance phenomena… and the influences of both the open ocean and land influx to take into account.
Enclosed or semi-enclosed seas (Baltic Sea, Mediterranean Sea, etc.) are in a large part “coastal”, since a lot of their waters is less than 50 km from land, if we use this definition of coastal, fit for onboard altimeter & radiometer. Continental shelf proper, which is another possible definition of coastal, can be much narrower, though, especially in the Mediterranean Sea, but the very narrow Adriatic Sea, or the Aegean Sea with its many islands fill in both definitions.

Coastal currents & their forecasting

The knowledge of coastal currents is of foremost importance for many marine uses – navigation, local fisheries, aquaculture, wildlife conservation, tourism… and also the design and building of infrastructures such as harbors. From this knowledge, and from the operational observation of these currents, forecasting can be computed, which is important to such practical applications. Forecasting pollutant dispersion, in particular, is a major need so as to place the mitigation means at the best possible times and locations. 

Mean sea level rise at the coast
Among the concerns about mean sea level rise, the questions of its impacts on the coasts are of foremost importance. Current coastal flooding hazards are the most urgent to assess, in case of storm surge in particular. In the long term, mapping future risks on the coasts, including on the habitations and infrastructures is vital. But with often land vertical movements, erosion or sediment deposits, the answers are complex. Altimetry helps in bringing the ocean component, but other data must be taken into account, and potential extrema assessed. 

Waves

High waves in the open ocean are a risk to navigation. Close to the coats, it is also true, with even more ship on the water. There are also infrastructure to design and build according to long term wave statistics.