Analysis and Prediction of Significant Wave Height in the Beibu Gulf, South China Sea

Abstract

A series of 40-year significant wave height (SWH) data were extracted from the ERA-Interim data set of the European Center for Medium-Range Weather Forecasts (ECMWF), for the Beibu Gulf and its adjacent waters in the South China Sea from 1979 to 2018. After that, data were first aggregated to annual and monthly average data. Through the analysis, the annual SWH had grown since 1984, reached a significant level in 1995, and reached a maximum 1.068 m in 2011. The monthly SWH values between April and September were lower than those of other months. Additionally, the corresponding analysis on wind speed data demonstrated that variation in wind speed was consistent with SWH from 1979 to 2018, but the overall trend of SWH increased while wind speed decreased. The decrease of wind speed could be attributed to the weakening of the East Asian monsoon, and the westward swell induced by the gales that occurred in the northeast of the South China Sea resulted in the increase of SWH in the study area. Finally, a multiple sine function decomposition neural network (MSFDNN) was employed to forecast monthly SWH over the next 10 years. The predicted results revealed that the MSFDNN was well-performing for forecasting monthly SWH.