Is sea level rise larger near the coast?

Satellite altimeter data from the last two decades put the estimate for present-day global mean sea level rise at 3 mm/year. But how important is the global figure if we only see the impact at the coast line? It is hence prudent to ask: What is the sea level rise near the coast? Is it different from the global number, and if so, why? Preliminary analyses show that the sea level in a 200 km radius from the coast is actually rising faster, about 4 mm/year, but this value is dominated by the large 5 mm/year rise the Indonesian Sea, which value is largely influenced by El Niño-Southern Oscillation (ENSO) variability. Some other contributors to increased coastal sea level rise would include warming of the coastal waters. Another analysis that can shed some light on what components are currently the largest contributors to sea level change is the separation of the regional time series into empirical orthogonal functions (EOFs). The largest EOFs show the predominant features: seasonal heating, ENSO, PDO, and North Atlantic Oscillation (NAO) and very little power that is purely coastal. That makes us conclude that, outside the aforementioned contributors, the actual eustatic and steric sea level rise is largely a homogeneous global phenomenon. In this presentation we will also look at other contributors to (apparent) sea level rise: orbit error, errors in propagation corrections and tide models, and global isostatic adjustment (GIA). Sea level rise measured by the Jason-1 radar altimeter (2002-2009) as a function of distance from the coast (black). The amplitude of the annual sea level variation is shown in gray.