Simulation Of Particle Tracking Of Alexandrium In Bay Of Fundy Gyre

Coastal seas are the most interactive areas with humans.Changes in ocean currents have important impacts on fisheries,shipping,pollution and military affairs.Between April and August in each year,near-shore residents living in the northeastern United States and eastern Canada are often affected by the bloom of toxic dinoflagellate Alexandrium fundyense,leading to paralytic shellfish poisoning(PSP).The Bay of Fundy has one of the highest concentrations of cells.In the offshore waters of the Bay of Fundy,Alexandrium vegetative cells(including duplets)concentrate in the upper layers,with highest concentrations observed at the surface.Concentrations decrease with depth.They are often retained within a counterclockwise gyre due to a combination of tidal rectification and buoyancy forcing but there is obviously significant uncertainty in the transport mechanisms.In order to investigate the speed and direction of transport and particle retention of the gyre to manage shellfish resources and reduce shellfish poisoning events,this paper studies the particle motion of Bay of Fundy using a combination of drifter observations and ocean model output.The main research contents are as follows:(1)Ocean model verification1)We used the hindcast fields from both Finite Volume Community Ocean Model(FVCOM)and the Regional Ocean Models System(ROMS)as examples of well-respected high resolution models in this area.The drifters(depths between lm and 15m)deployed in Bay of Fundy from 2004 to 2010 in April through August were used to validate the ocean models,and it can be seen that ROMS is better than FVCOM in ocean current simulation.2)Next,using mooring monitoring ocean current data to verify the FVCOM simulation ocean currents,it was found that the accuracy of the FVCOM ocean model in some ocean areas during 2009 to 2016 is problematic.3)Using the Mooring temperature and salinity monitoring data to verify the simulated temperature and salinity of FVCOM,it was found that the simulated temperature,salinity of FVCOM is consistent with the actual temperature and salinity change trend.Although there is some difference,it can be applied to marine monitoring.(2)Bay of Fundy Gyre monitoring by drifter and ocean model1)The existence of the gyre was confirmed by the drifter data(1 m and 15 m)from NOAA in April through August months of 1978 to 2010.We found that the counterclockwise Bay of Fundy gyre intensity between mid-June to August was slightly stronger than between April and mid-June,and the area was larger.2)By using drifter and model monitoring,we can see that the ocean current which left the gyre move in three directions:(A)moving southwest along the east of Grand Manan Island,(B)moving southwest along the west of Grand Manan Island,and(C)northward along Nova Scotia's west coast.3)56 drifters(lm and 15m)from 2004 to 2010 in April through August departed from the bay of fundy,of which 42 were moving from both sides of the Grand Manan Island to the southwest,14 of which moved along the west coast of Nova Scotia to the northeast.The number of drifters flowing to the southwest was more than to the northeast.(3)Alexandrium algae particle simulation tracking and Bay of Fundy gyre characteristics analysis1)According to the gyre boundary we got before,100 particles were arranged inside the Bay of Fundy gyre and the ROMS model with high precision was used to track the particle tracking.By studying the trajectories of particles which are placed 1 meter and 15 meters below sea level from 2004 to 2010 on March 31 through August.Every time you track 30 days,start again after 5 days.2)It was found that the mean particle retention rate was near 70%after 15 days and about 60%after 30 days but there was significant interannual variability especially in the spring months of April and May.In the mean,transport to the southwest was stronger.Before Mid-June,particles leaked primarily to the south and west but after Mid-June a larger portion moved northerly.3)At 15 m below sea level,it can be found that the particle retention of the gyre was slightly higher than it in the surface.During the whole period from April to August,the particles tended to move southwestward and moved northeastwards weakly.4)Experimental results show that the particle retention of Bay of Fundy gyre and the characteristics of particle leaving the Bay of Fundy gyre are mainly related to wind pressure intensity,the river flow in the nearby St.Join river,the temperature and salinity of seawater.The main innovations are as follows:(1)Explored a method combining marine drifter monitoring and marine model monitoring to study the circulation of the ocean.(2)On the basis of particle trajectory tracking,methods of calculating the particle retention and the analysis of particles after leaving circulation are studied.(3)To study the method of analysis of ocean gyre influencing factors.