| 摘要(英) |
The neritic area ocean current changes very big by the wind, but limited by the past instrument resolution and lacked the fine resolution of the ocean current vertical data that would be difficulty to described the vertical stratification ocean current response to suffer a strong stiff wind. This research use vertical fine resolution ADCP ocean current data (2001/5/22~2001/6/26), discusses the Wuchiu sea area ocean current characteristic, including the tidal current, the sub-tidal current, the sub-tidal current influence by the wind and under the wind produces the surface Ekman layer and the Ekman layer at the bottom of the ocean characteristic, as well as the change of the viscosity in the boundary layer.
According to the observed data, the semi-major axis direction of the tidal current ellipse is consistent with the isobaths.The density stratification have huge influence in the tidal current , and leads the vertical tidal current to divide into obviously two layers. But the sub-tidal current influenced depths by the wind probably for upper formation 10 m, similarly sub-tidal current also affected by the density stratification in a big way, such as to the influenced layer to be unable developing. In the end of the data, it happened to a typhoon process. Before the typhoon processing , the surface and the bottom of Ekman layer are not all clear; but when the typhoon closest the station, the flow field all clearly appeared the surface and the bottom Ekman layers, but the surface Ekman layer is unable to develop the bottom, because of the density stratification influence , the flow field structure is divides into two layers; After the typhoon, the bottom flow field rotates clockwise, but on 26th the bottom and the surface Ekman layer becomes not obviously.
By the ocean current accumulated vector diagram discovered the ocean current develops the surface layer Ekman layer, because of the friction force influence, the bottom current developing the bottom Ekman layer from instrument 17 m apart. Utilizing the effective viscosity formula of depth Zikanov et al. (2003) ,substitute actual data, assumed the bottom boundary layer viscosity along with depth change ν(z), substitute back to the original momentum equilibrium equation, simply estimates the viscosity changes with depth. The result of regression curve is an exponential curve, and the viscosity in the bottom boundary layer bigger along with the bottom distance increasing but it does not include below boundary layer 3 m apart. With Zikanov et al. (2003) is apart from the instrument 1-17 m to the viscosity change to be approximately similar, only different in the bottom, the Zikanov curve is apart from below instrument 5 m, the viscosity become increase, but the viscosity of data analysis in this research goes on lessening to the instrument 3 m apart. |
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