Research On The Influence Of Model Spatial Resolution On The Simulation Of Dynamic Processes In The South China Sea

The South China Sea is the largest marginal sea in the western North Pacific Ocean and contains abundant oceanic dynamic processes.The South China Sea spans multiple straits and exchanges water between the Pacific and Indian Oceans.It is a typical tropical edge basin.The 20 latitudes in the north and south make the semi-enclosed sea basin in the South China Sea have many dynamic features similar to those in the ocean.The multiple spatial-temporal scales of the South China Sea circulation have certain local air-sea interaction backgrounds.The formation reasons are related to the monsoon and other outer forcing.The Luzon Strait is the only deep water channel connecting the South China Sea and the Pacific Ocean.The exchange of water in the Kuroshio Current and within the Strait also affects the deep structure of the South China Sea circulation.Therefore,the scientific research on the South China Sea and the Luzon strait has always been the focus of Marine scientists at home and abroad.In this paper,we use the Regional Ocean Modeling System(ROMS)to simulate the zonal transport structure of the Luzon Strait and the circulation structure of the South China Sea.Nesting of different locations in the South China Sea is done using the model nesting method.The use of model nesting can not only save computing time,but also improve the model resolution of key research areas,making the model results closer to the true value.After obtaining the results of numerical models based on different spatial resolutions,in order to ensure the correctness of subsequent analysis and calculation,the credibility of the model is firstly verified.Surface temperature,salinity,and flow field maps and remote sensing data in the South China Sea and adjacent sea areas in winter and summer are selected.After the comparative study,it can be seen that the model surface temperature,salinity,and the South China Sea circulation pattern coincide with the remote sensing data modality.However,in different experiments,the Kuroshio morphology invaded by the Luzon Strait is quite different from the geostrophic flow field.One point will be discussed later through specific calculations.Because the exchange of water in the Luzon Strait is important for the circulation structure of the South China Sea,the Luzon Strait section was used to calculate the water flux of the Luzon Strait,and it can be clearly seen that there are nested high spatial resolution models in the Luzon Strait.Water exchange has a clear "sandwich structure.”However,in the model with low spatial resolution,there is no obvious "in-out-in" three-layer structure,which may be due to the low resolution,which affects the terrain.In order to study the relationship between the circulation structure of the South China Sea and the water exchange in the Luzon Strait,the South China Sea is divided into surface,upper,middle,and bottom layers by artificially layering the average of the surface,upper,middle,and bottom layers of the South China Sea in winter and summer,respectively.The flow field diagram observing the flow state of the flow field gives the circulation pattern of each layer,and at the same time,it also theoretically calculates the velocity loop on the South China Sea boundary.Combining the above two methods,the high-resolution model results show that in the South China Sea,the three-layer structure of cyclonic-anticyclonic-cyclonic circulation appears in the upper,middle,and lower layer circulations in winter and summer respectively.However,no obvious three-layer structure was seen in the low-resolution model results.