Seasonal circulation and influence factors of the Bohai Sea: a numerical study based on Lagrangian particle tracking method

Abstract

Seasonal circulation of the Bohai Sea (BS) in 1992 was investigated using Lagrangian particle tracking method. The hydrography of the BS was simulated based on an unstructured grid, finite-volume, three-dimensional primitive equation ocean model. With the use of the unstructured triangular grid, the model can easily fit the irregular coastal boundary of the BS. The simulated tides, tidal current, and thermohaline field agreed well with the observations. The transport of particles has three-dimensional structure in the BS. Compared with central Bohai and Bohai Strait, the differences of particles' transportation between surface and bottom layer in three bays are small. The circulation in the summer is stronger than that in the winter, with the average residual velocity in the surface layer being about 3.7 cm/s during the summer while only 1.8 cm/s during the winter. Using the same model, several well-designed numerical experiments were performed to investigate the effect of oceanic tide, river discharge, wind stress, and thermal stratification on the circulation. It is shown that winds play an important role in the circulation of the BS during both the winter and the summer. Density circulation is important during the summer; however, it is negligible during the winter. River runoff only affects the area around the river mouth. Compared with wind and thermohaline effect, the contribution of tides is small during the summer, and the circulation under only M 2 tidal constituent could not reflect the actual circulation of the BS.

Circulations associated with cold pools in the Bohai Sea on the Chinese continental shelf

“…Previous studies suggested the importance of baroclinic structure to the basin-scale gyre (Liang et al, 2006;Wang et al, 2010) and the importance of anti-cyclonic flow in the central Bohai Sea . In comparison, our climatological simulations reveal that the Bohai Sea circulation is characterized by a basin-scale cyclonic gyre and a few co-existing eddy-like structures from May to…”

“…Monsoon wind plays an overwhelming role on the circulation in winter (Miao and Liu, 1988), while the rather weak winds in summer plays a less important role in driving the circulation except at the surface (Zhao and Shi, 1993). Recent modeling studies suggested the importance of a horizontal density gradient to the basin-scale gyre (Liang et al, 2006;Wang et al, 2010). Using a diagnostic model, Wan et al (2004) recognized the significance of density-driven circulation using a set of experiments based on a hydrographic survey conducted in August 2000.…”

Numerical Simulation Research on Flow Characteristics and Influential Factors of Wuxing Lake

“…Wuxing Lake is a shallow lake with small areas and irregular shapes. Unstructured grids [11,[21][22][23] were used here to fit the complicated lake boundaries better. There were altogether 1213 grids of an average size of 10m10m and 765grid nodes.…”

Spatial Interpolation of Tidal Data Using a Multiple-Order Harmonic Equation for Unstructured Grids

“…The Bohai Sea is a semi-enclosed embayment on the coast of China in the northwest Pacific Ocean, and its tidal system has been well documented from observations and hydrodynamic model simulations [23][24][25]. The test data set for this case consists of M 2 , K 1 , S 2 , and O 1 tidal constituents from 31 observed tidal stations in the Bohai Sea [23], of which 29 are near the coast, and two are from islands in the mouth of the Bohai Sea.…”