Analysis of Wave Distribution Simulated by WAVEWATCH-III Model in Typhoons Passing Beibu Gulf, China

Weizeng Shao,Wei Tan,Yexin Sheng,Juncheng Zuo,Huan Li,Jian Shi,Qiyan Ji

doi:10.3390/atmos9070265

Abstract

The Beibu Gulf is an important offshore region in the South China Sea for the fishing industry and other human activities. In 2017, typhoons Doksuri and Khanun passed the Beibu Gulf in two paths, at maximum wind speeds of up to 50 m/s. Typhoon Doksuri passed the Beibu Gulf through the open waters of the South China Sea and Typhoon Khanun moved towards the Beibu Gulf through the narrow Qiongzhou Strait. The aim of this study is to analyze the typhoon-induced wave distribution in the Beibu Gulf. WAVEWATCH-III (WW3) is a third-generation numeric wave model developed by the National Oceanic and Atmospheric Administration (NOAA), which has been widely used for sea wave research. The latest version of the WW3 (5.16) model provides three packages of nonlinear term for four wave components (quadruplets) wave–wave interactions, including Discrete Interaction Approximation (DIA), Full Boltzmann Integral (WRT), and Generalized Multiple DIA (GMD) with two kinds of coefficients, herein called GMD1 and GMD2. These four packages have been conveniently implemented for simulating wave fields in two typhoons after taking winds from the European Centre for Medium-Range Weather Forecasts (ECMWF) at 0.125° grids as the forcing fields. It was found that the GMD2 package was the recommended option of the nonlinear term for quadruplets wave–wave interactions due to the minimum error when comparing a number of simulated results from the WW3 model with significant wave height (SWH) from ECMWF and altimeter Jason-2. Then the wave distribution simulated by the WW3 model employing the GMD2 package was analyzed. In the case of Typhoon Doksuri, wind-sea dominated in the early and middle stages while swell dominated at the later stage. However, during Typhoon Khanun, wind-sea dominated throughout and swell distributed outside the bay around the east of Hainan Island, because the typhoon-induced swell at mesoscale was difficult to propagate into the Beibu Gulf through the narrow Qiongzhou Strait.

Highlights

The South China Sea is an area where typhoons frequently occur each year
We evaluate the applicability of the four packages of nonlinear terms in the regional South China Sea; and the best option is selected to simulate the waves from 1 September to 31 October 2017, during which two typhoons, Atmosphere 2018, 9, x FOR PEER REVIEW
It is found that the maximum significant wave height (SWH) is nearly 4 m, and the simulated SWH using the WRT package is obviously smaller than the results using other packages, especially around Hainan island for Typhoon Doksuri

Summary

Introduction

The South China Sea is an area where typhoons frequently occur each year. The Beibu Gulf, which is a semi-enclosed gulf, is a critical fishery resource and an important offshore region for human activities in the South China Sea. typhoons from the low latitude regions of the Pacific. Ocean usually pass through the Beibu Gulf in the summer and it is reported in [1] that there were. Typhoon affects the variation of water level in Beibu Gulf [2] and causes geological disaster by rainstorm [3]. Typhoon-induced waves can have disastrous effects, especially in coastal regions. It is worth studying the distribution of typhoon-induced waves in the Beibu

Objectives

Results

Discussion

Conclusion