防城港外海海域夏冬季周日潮流的准调和分析

Quasi Harmonic Analysis of Diurnal Current in Summer and Winter in Fangchenggang Offshore Area

关键词:  防城港湾  准调和分析  潮流特征  余流  潮流椭圆  周日变化

Key words:  Fangchenggang Bay  quasi harmonic analysis  tidal characteristics  residual current  current ellipse  diurnal variation

摘要:

为深入研究防城港外海海域的潮流特征，通过引入差比关系，对防城港外海海域4个站点夏、冬季2个周日观测所得的表、中、底层海流的短期资料进行准调和分析。结果表明：防城港外海潮流属于混合潮流，部分海域属于正规全日潮流；潮流中旋转流和往复流同时存在，以旋转流为主，潮流椭圆长轴为东北-西南向；最大可能流速出现在表层，由表层至底层余流流速逐渐减小。夏季，防城港湾西侧余流方向为西南向或西北向，而东侧余流方向为东北向；冬季，除湾口为西南向外，其余海域余流方向均为东北向，余流与地形、风场、温度和盐度等因素有关。周日潮流资料时间较短，受天气、海况、观测时间等因素影响较大，计算的潮流性质略有差异。

Abstract:

In order to deeply study the tidal current characteristics offshore area in Fangchenggang,a quasi harmonic analysis on the short-term data of the surface,medium and bottom currents obtained from the observations at four stations over two days in summer and winter in the offshore area of Fangchenggang is carried out by introducing the difference ratio relationship.The results showed that the offshore tidal current of Fangchenggang belongs to mixed tidal current,and parts of the area belong to regular diurnal tidal current.Rotating flow and reciprocal flow exist simultaneously,mainly rotating flow.The long axis of current ellipse was northeast-southwest.The maximum possible velocity appeared in the surface layer,and the residual flow velocity decreased gradually from the surface to the bottom.In summer,the direction of residual current on the west side of Fangchenggang Bay was southwest or northwest,while the direction of residual current on the east side was northeast.In winter,the direction of residual current was northeast,only southwest near the mouth of Fangchenggang Bay.The residual current was related to topography,wind field,temperature and salinity.The diurnal current data is relatively short,which is greatly affected by weather,sea conditions,observation time and other factors,and the calculated tidal current properties are slightly different.