On Lowest Astronomical Tide around Japanese Coasts.

Abstract

International Hydrographic Organization （IHO） resolved that Lowest Astronomical Tide be adopted as chart datum. The heights of LAT of 184 tide stations around Japanese Coasts are calculated with harmonic constants of 60 tidal constituents. As a result, the heights of LAT are lower than those of the present chart datum at every station, and the lowest value is more than 50 cm lower than chart datum. Furthermore, we find that it is probable that actual sea level often falls below chart datum along the coasts of Japan Sea, even if LAT is adopted as chart datum.