基于长期观测的辽东湾口东部海域水动力特征研究

Study on hydrodynamic characteristics in the eastern part of Liaodong Bay Mouth based on long-term observation

辽东湾口东部海域是辽东湾与渤海中部进行物质和能量交换的主要通道之一。本文利用坐底式海床基平台获取的近8个月的水动力连续观测资料,通过谱分析和调和分析方法对该海域的潮汐、潮流特征进行分析,并讨论了余流及底层温度的季节变化规律。研究结果表明:该海域潮汐属于不规则半日潮,平均潮差为0.95m,最大可能潮差为2.27m。潮流属于不规则半日潮流,M2分潮流为其优势分潮流。主要分潮流运动形式为往复流,最大流速方向为西南-东北向。余流的季节性特征较为明显:秋季,余流流速在中层达到最大,流向以西南向为主;冬季,余流流速垂向变化较小,并呈西南偏西向流动;春季,流速随深度增加而减小,流向从表层至底层呈现逆时针旋转的特征。受底层潮流、水平温度梯度及海面温度日变化的影响,底层温度表现出短期的高频变化特征:秋季,短期振荡以半日周期信号为主;冬季,全日周期信号较为显著;春季,短期振荡的现象较弱。

The sea area in the eastern part of Liaodong Bay Mouth is a key passage through which the mass and energy are exchanged between the Liaodong Bay and the central Bohai Sea.In this paper,based on the eight-month continuous observed data obtained from the seabed based platform,we firstly analyzed the characteristics of tide and tidal current,and then discussed the seasonal variation regularities of residual current and sea bottom temperature in the sea area by means of spectral and harmonic analysis.The results were shown as follows：the tide in the sea area was an irregular semi-diurnal one with the mean tidal range 0.95 mand the maximum possible tidal range 2.27 m,respectively.The tidal current was an irregular semi-diurnal one,and the M2 tidal current constituent was dominant.The motion type of the principle tidal current constituents was rectilinear,with the maximum tidal velocity in the direction of southwest-northeast.The residual current showed remarkable seasonal features.In autumn,the residual current flowed southwestward and showed a parabolic-shaped profile,with the maximum velocity observed in the mid-layer.In winter,the residual current flowed in the direction of west-southwest with little variability of velocity in vertical.In spring,the residual current,showing a cyclonic spiral,was weakened from the surface to the bottom layers.Affected by tidal current,horizontal temperature gradient in the sea bottom and diurnal variation of SST,the high-frequency variation of bottom temperature was observed in the bottom layer.In autumn,the signal of semi-diurnal period was dominant,whereas in winter the signal of diurnal period was notable.These pulses of short-term variability were considerably suppressed in spring.