Evaluation of different wind resources in simulating wave height for the Bohai, Yellow, and East China Seas (BYES) with SWAN model

Abstract

The performance of seven wind resources in simulating the significant wave height (Hs) for the Bohai, Yellow, and East China Seas (BYES) was evaluated with a numerical wave model (Simulating WAves Nearshore, SWAN) for the year 2016. The model outputs were carefully compared with coastal oceanic station data and altimeter observations. Most wind fields can deliver good wave simulations in our study area. The fifth generation atmospheric reanalysis of the European Centre for Medium-Range Weather Forecasts (ERA5) performs the best in the coastal region, while Cross-Calibrated Multi-Platform version 2 (CCMPv2) performs the best in the inner region. Through presenting the wave model performance/wind field quality as a function of sea state/wind condition, we revealed that the positive/negative bias of lower/higher wind speed in the forcing wind field is highly correlated to the overestimation/underestimation of lower/higher Hs in the simulation results. In addition, the SWAN model with default settings tends to increase the negative biases in the resulting Hs. A conclusion related to all wind fields is that the wave model performance is generally better in the south than in the north, reaching the best in the South Yellow Sea, followed by the East China Sea, North Yellow Sea, and Bohai Sea. Further analysis indicated that the relatively poor wind field quality of low wind speeds directly results in larger simulation errors for lower wave heights. Meanwhile, the northern sea areas are dominated by lower wave heights, thereby leading to the poorer wave simulations here.