and an in situ
mean sea surface is available for each of the sites with a
spatial resolution of 5 104 degrees (about 50 m) over
20 km. In Senetosa, the slope is clearly non-negligible as
it is in the order of 3–4 cm/km over the portion of the
in situ mean surface where altimeter data are available
(up to about 5 km from the coast, due to the land contamination
in the altimeter footprint) and dramatically
increases over the last kilometres to the shore, where the
tide gauges are installed. Consequently, part of Eq. (2)
can be rewritten with the introduction of the point of comparison
located on this high resolution surface (point C in
Fig. 1