| 内容提要: |
Abstract: Waves in shallow water have huge energy that greatly influence the construction of marine engineering, voyage, fishing and aquiculture etc. Wave characteristics and processes should be carefully studied to understand the mechanism and to forecast accurately. One month wave observations were carried out off south coast of Dong-Chudao, Heini Bay during winter and summer of 2016, respectively. Acoustic doppler velocimeter (ADV), acoustic doppler current profiler (AD2CP) and wave-tide gauge mounted on a bottom-tripod were used at depth of 8m. All three instruments could measure the high frequent water level variation and obtain the significant wave height (Hs) and peak wave period (Tp) by spectrum analysis. Wave characteristics derived by three instruments were in consistent so only result from ADV data was shown here. Local wind was measured by auto-meteorology station and wind field of the Yellow Sea was obtained from reanalysis data of ECMWF. The analysis indicate that swell were dominant both in winter and summer. Sea shore influence to the wind-sea greatly due to the shorter wind area when northerly wind blow. In winter Hs maximum was 1.18m while in summer Hs=1.49m. Hs between 0.1m to 0.4m were 75.3% in winter and 59.7% in summer while 0.4m<Hs<0.7m were 9% and 26.6% , respectively. Tp between 3s to 6s were 41.8% in winter and 27.1% in summer while 6s<Tp<10s were 57.3% and 66.5%, respectively. There were two distinct wave growth processes in winter. At the beginning of wave growth, Hs was controlled by local wind. Then the local wind changed direction accompanying with growing swell which induced by remote wind field. Finally large swell became dominant because east-south wind occurred in the Yellow Sea two days before. Three notable wave growth processes were recorded in summer. First two of them were dominant by swell-wind sea-swell alternatively and peaks of Hs were determined by swell. The last one, although under breeze locally, was totally swell leading with large Hs caused by sustained southerly wind remotely. All observed spectral characteristics could be used to modified the wave model. The observation show that there are no very rough sea at this area even the wind speed exceed 15m/s. So it is a good place for aquiculture or engineering construction from point view of waves.
Keywords: shallow water; wave characteristics; processes analysis; Heini Bay |