What does the tide gauge mean?

The tide table is displayed by coordinate chart, and the abscissa is 24 hours per day, which is generally represented by 0-6- 12- 18-0. The ordinate is the height of high tide and low tide every day, where 0 represents the altitude of the place.

Tidal phenomena can be regarded as the superposition of tidal components in many different periods, so the tidal height at any moment can be expressed as the height of average sea level on the tidal height datum, the circumferential frequency of tidal components and the intersection factor, where d is the astronomical phase angle at the beginning of Greenwich, and h is the harmonic constant-amplitude and lag angle of tidal components.

In the port where semidiurnal tide is dominant, the tidal characteristic values such as average high tide interval, average high tide rise (average high tide of spring tide) and average low tide rise (average high tide of small tide) are usually listed. In the ports where the diurnal tide is dominant, the tidal characteristic values of the return tide and the vernal equinox tide are generally listed, which can be used to calculate the approximate tidal time and tidal level height of each port and understand the tidal characteristics of its ports.

In tide tables, charts and tables are usually attached to facilitate calculation. These charts and tables are used to calculate the tide level at any time between high tide and low tide or at any time when any tide level appears when high tide and low tide are known. In addition, some tide tables are accompanied by the harmonic constants of the main tidal components of each port, or briefly introduce the tidal current in the nearby waters.