Hydrographic Office (HO) of Marine Department has introduced a computer-based Tidal Stream Prediction System (TSPS) to generate tidal stream predictions for some 1,200 points across Hong Kong waters. The predictions include the tidal stream speed and direction for each point at 15-min interval for two years and one day. The prediction period includes an immediate past year, current day and a year thereafter. Such information is available to the public users for on-line access and downloading in this website.

Accuracy of Prediction

The tidal stream prediction made by Hong Kong Tidal Stream Prediction System is based on the tidal components generated from the updated Hong Kong Tidal Atlas model. The tidal components consist of amplitude and phase of 66 chosen tidal constituents. These predictions will deviate from the actual conditions in the field since temporal and localised meteorological effects and non-tidal flow variations could not be taken into account. Moreover, its accuracy further depends on the chosen tidal constituent set, accuracy of the underlying model, length of the simulation and location of the data points within the model, etc.

According to the comparison of the predicted data with the actual field observed data, the average difference in current peak magnitude ranges from 0.03 m/s to 0.21 m/s, while the average phase difference in peak velocity was about 17 minutes.