What is the difference between a reference station and a subordinate station?
The following information was copied from NOAA’s web site on 2007-02-17. The publication of full daily tide predictions is necessarily limited to a comparatively small number of stations. These stations are referred to as “reference stations”. Tide predictions for more than 3000 other locations, referred to as “subordinate stations”, can be obtained by applying specific differences to the daily tide predictions for one of the reference stations. […] Caution: The time differences and height ratios used to calculate predictions at subordinate stations are derived from a comparison of simultaneous tide observations at the subordinate station and its reference station. Because these adjustments are constant, they may not always provide for the daily variations in the actual tides, especially if the subordinate station is some distance from the reference station. Therefore, although the application of time differences and height ratios will generally provide reasonably accurate approximat
