A nested circulation model system based on the Princeton ocean model(POM) is set up to simulate the currentmeter data from a bottom-mounted Acoustic Doppler Profiler(ADP) deployed at the 30 m depth in the Lunan(South Shandong Province,China) Trough south of the Shandong Peninsula in the summer of 2008,and to study the dynamics of the circulation in the southwestern Huanghai Sea(Yellow Sea).The model has reproduced well the observed subtidal current at the mooring site.The results of the model simulation suggest that the bottom topography has strong steering effects on the regional circulation in summer.The model simulation shows that the Subei(North Jiangsu Province,China)coastal current flows northward in summer,in contrast to the southeastward current in the center of the Lunan Trough measured by the moored currentmeter.The analyses of the model results suggest that the southeastward current at the mooring site in the Lunan Trough is forced by the westward wind-driven current along the Lunan coast,which meets the northward Subei coastal current at the head of the Haizhou Bay to flow along an offshore path in the southeastward direction in the Lunan Trough.Analysis suggests that the Subei coastal current,the Lunan coastal current,and the circulation in the Lunan Trough are independent current systems controlled by different dynamics.Therefore,the current measurements in the Lunan Trough cannot be used to represent the Subei coastal current in general. A nested circulation model system based on the Princeton ocean model (POM) is set up to simulate the currentmeter data from a bottom-mounted Acoustic Doppler Profiler (ADP) deployed at the 30 m depth in the Lunan (South Shandong Province, China) Trough south of the Shandong Peninsula in the summer of 2008, and to study the dynamics of the circulation in the southwestern Huanghai Sea (Yellow Sea). The model has reproduced well and the observed subtidal current at the mooring site. The results of the model simulation suggest that the bottom topography has strong steering effects on the regional circulation in summer. The model simulation shows that the Subei (North Jiangsu Province, China) coastal current flows northward in summer, in contrast to the southeastward current in the center of the Lunan Trough measured by the moored currentmeter. the analyzes of the model results suggest that the southeastward current at the mooring site in the Lunan Trough is forced by the westward wind-driven current along t he Lunan coast, which meets the northward Subei coastal current at the head of the Haizhou Bay to flow along an offshore path in the southeastward direction in the Lunan Trough. Analysis suggests that the Subei coastal current, the Lunan coastal current, and the circulation in the Lunan Trough are independent current systems controlled by different dynamics. There fore, the current measurements in the Lunan Trough can not be used to represent the Subei coastal current in general.