Improved Prediction of Local Significant Wave Height by Considering the Memory of Past Winds

Wave and water depth were measured with an instrumented tripod in the Yellow River Delta from 9 December 2014 to 29 April 2015. Concurrent wind data were also collected from a nearby wind station. A high-precision model for predicting local significant wave height (H-s) with wind speed (v(w)) is constructed using an improved data-driven approach. The proposed model realized high accuracy as it solves the problem that the H-s falls too fast during the wind-decreasing periods. It was tackled by considering the remaining influence of historical v(w) on the present H-s via incorporating a memory curve of the past wind effect. This innovative approach significantly improves the prediction (R-2 from 0.60 to 0.83). The winds in the past 24 hr still left an influence on the waves at the observation site although the influence decreases with time. Physically, it is an implicit but simpler consideration of wind fetch/duration. Further data modeling experiments indicated that the decisive factor for the H-s at the site is the wind speed. Wind directions slightly improve the prediction, indicating that waves are slightly affected by the underwater seabed slope along different wind directions, and northwest winds cause the strongest waves at the site. Adding atmospheric pressure or water depth even reduces the accuracy, which indicated that storm surges and wave deformations under different tide levels have a weak impact on H-s. The proposed local wave model can be easily constructed with available wind and wave data, making it expandable to other regions dominated by wind waves.