Numerical Study Of Jellyfish Drift And Diffusion In Coastal Waters Nearby Qinhuangdao Based On ROMS Model

In recent years,the structure and function of marine ecosystem have changed due to the impact of global climate change and human activities.Since the occurrence of green tide and red tide disasters,jellyfish outbreak has also become a serious marine ecological disaster,which has attracted much attention.The outbreak of jellyfish will cause significant economic losses to coastal cities,such as the blockage of water intake of coastal power plant,the lack of guarantee of bathing beach safety,the reduction of fishery production and a series of problems.Qinhuangdao sea area,located in the west of Bohai Sea,is an important port and aquaculture base in northern cities of China.White Chardonnay jellyfish is likely to become a disaster causing jellyfish in the sea area.In order to ensure the safety of the coastal waters of coastal cities,exploring the drift path and aggregation and outbreak process of jellyfish,and clarifying the relationship between jellyfish drift and diffusion and hydrodynamic forces are important ways to solve jellyfish disasters.Based on the ROMs regional ocean model,the hydrodynamic environment of Qinhuangdao sea area is established.The ltrans model method is used to simulate the drift and diffusion path of white Chardonnay jellyfish in Qinhuangdao sea area,obtain the drift path and aggregation area distribution of white Chardonnay jellyfish,analyze the spatial distribution characteristics of Chardonnay jellyfish,and discuss the relationship between the distribution of jellyfish and hydrodynamic process in this sea area.It provides a basis for the interception and salvage of jellyfish in the sea area and plays an important role in the prevention and control of coastal jellyfish in the sea area.According to the observation of Qinhuangdao sea area in 2020,the white Xia jellyfish space is distributed in two bands,and the characteristics of large number of jellyfish are found in the second section.At the same time,combined with the north in and south out trend of residual current in July in summer simulated by ROMs,a numerical simulation test is designed to simulate the drift and diffusion path of jellyfish.The results show that:（1）after a section of Qinhuangdao sea area,the jellyfish will drift in three directions:（1）the jellyfish will drift directly to the southwest along the coast;（2）After the jellyfish drifted from the initial position of a section,it was brought to the vortex in the northeast of a section for drift movement by the action of tide and ocean current,and then left the vortex and drifted to the southwest;（3）Taking the farthest station of a section from the coast as the initial position of the jellyfish,the jellyfish first drifted to the southwest,and then offshore to the southeast;Combined with the actual observation results,the spatial distribution of Xia jellyfish conforms to the drift characteristics of（1）and（2）directions.For the（3）direction,because the jellyfish is not investigated at the initial position,it is impossible to compare with the measured results.In addition,it is observed that the Chardonnay jellyfish in Qinhuangdao sea area gather seriously in the second section,and the corresponding aggregation area is obtained in the numerical simulation.（2）Judging from the drift track of white Xia jellyfish in Qinhuangdao sea area in July2020,the main dynamic factor affecting the drift and diffusion of jellyfish is ocean current.Therefore,suggestions are put forward for the management of jellyfish,which are elaborated from the aspects of en route interception,gathering area removal,monitoring and early warning,hoping to provide guarantee for the prevention of jellyfish disasters in the coastal waters of Qinhuangdao sea area.