Numerical study of water exchange in the Jiaozhou Bay and the tidal residual currents near the bay mouth
Numerical study of water exchange in the Jiaozhou Bay and the tidal residual currents near the bay mouth
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作者：
Q. Fangli
基于普林斯顿海洋模式（POM），建立了覆盖胶州湾及青岛沿岸沃茨的正压潮流数值模式，并结合船载声学多普勒海流剖面仪（ADCP）的实测海流资料，对胶州湾口附近的潮流特征进行了研究。在潮汐模型中引入了水质子模型，模拟了JZB的水交换过程（M2、S2、K1、O 1、M4和MS 4），湾口航道潮流较强，实测大潮期最高流速为2.01 m/s，与ADCP观测结果基本一致。在团岛岬两侧发现一对潮余涡，潮余涡在团岛附近汇聚，形成57 cm/s的离岸急流。模拟的JZB平均水滞留时间（WRT）为71 d，平均半衰期（HLT）为25 d。WRT和HLT的水平分布在空间上很不均匀：水交换率最低的两个区域是JZB的西南西部和东北部，WRT在80 d以上，最高可达120 d，这种空间分布差异受潮（余）流结构和距湾口距离的控制。
A barotropic tidal model covering Jiaozhou Bay(JZB) and Qingdao coastal waters is developed based on Princeton Ocean Model(POM).This numerical model,combined with the field survey currents data obtained from a vessel-mounted Acoustic Doppler Current Profiler(ADCP),is used to investigate the characteristics of the tidal currents near the mouth of JZB.Furthermore,a water quality sub-model is coupled into the tidal model to simulate the water exchange processes in JZB.The tidal model includes six main tidal constituents(M2,S2,K1,O1,M4,and MS4),and reasonably reproduces tidal current field which is consistent with ADCP observation.The tidal current in the bay mouth channel is very strong.The observed peak current speed during spring tide period was 2.01 m/s.A couple of tidal residual eddies are found at both sides of the headland of Tuandao.The residual eddies converge near Tuandao,forming an offshore jet current of 57 cm/s.The modeled mean water residence time(WRT) in JZB is 71 days,and the mean half-life time(HLT) is 25 days.The horizontal distributions of WRT and HLT are quite uneven in space: they increase from the mouth to the top of JZB.The lowest water exchange rates are found in two regions,the west-southwest part and the northeastmost part of JZB,where the WRT is above 80 days with a maximum of 120 days,and HLT mostly exceeds 40 days.Such spatial distribution differences are controlled by the structure of tidal(residual) currents as well as the distance from the bay mouth.