Nadir
Point on the celestial sphere directly beneath the observer; opposite of zenith.
Neap tide
Minimum tidal range.
NOAA
National Oceanic and Atmospheric Administration.
Nodal correction
Correction to be applied to the harmonic constants to take into account the variations in the elements of the lunar orbit.
Noise
Component of the magnitude observed inaccessible to harmonic analysis.
NOOS
North West european shelf Operational Oceanographic System.
NTC
National Tidal Center.
NUNIEAU
Digitization of water levels.