Characterization Of Mesoscale Eddies And Their Effects On Chlorophyll

Mesoscale eddies are an important part of ocean circulation and play a significant role in the transport and mixing of matter,energy and heat in the ocean.Based on altimeter data,multisatellite integrated water color data,global drift buoy data,sea surface temperature and other multi-source observation data,the surface and vertical characteristics of the mesoscale eddy are investigated,and its effects on chlorophyll in the surrounding are discussed.Firstly,two special sea areas-Bay of Bengal and Sea of Japan are selected for preliminary analysis.The number of cyclonic eddies and anticyclonic eddies in the Bay of Bengal is similar.Under the influence of the cyclonic eddies,the chlorophyll concentration of the surrounding sea surface can increase by about 11%,while the anticyclonic eddies is the opposite,and chlorophyll changes rapidly in the mature and intensified stages of the eddy.Eddies in the Sea of Japan are different,and the areas with high frequency of eddies generation are distributed from southwest to northeast.Driven by the East Korea Warm Current and Tsushima Warm Current in the west and south of the Sea of Japan,the moving direction of eddies is basically consistent with the direction of the flow.The northern eddies may be related to the Riemann cold Current and the sub-polar front current.Subsequently,the above work is improved and expanded to construct the first "Global Ocean Mesoscale Eddy Atmospheric-Oceanic-Biological Interaction Observational Dataset ",which is published free of cost to comprehensively show the observation results of the influence of eddy on sea-atmosphere and organisms in the last 30 years.The study of global eddies using this dataset shows that there are a large number of eddies with large deformation rate and strength in the jet stream regions such as Kuroshio,gulf Current and Antarctic Circumpolar Current.Most of the eddies are generated from the east and then move westward,with small deflections toward the pole and equator.At the same time,the large-scale background field will also have a certain influence on the different physical characteristics of eddies.Eddies can cause anomalies of vertical water characteristics,the maximum depth of variation is about 100 – 200 m.The maximum depth of temperature anomaly in the northern Indian Ocean and Southern Ocean is slightly deeper,about 180 m,while the maximum depth of salinity anomaly in the North Pacific and North Atlantic is deeper,about 150 m.Finally,the dataset and the global eddies statistical characteristics were used to analyze the effect of eddies on surrounding chlorophyll.Under the influences of different polarities eddies,chlorophyll mostly shows a mononuclear structure,which is positively abnormal with depth,and the hyper nuclear center is about 80 m.At the same time,the chlorophyll captured by eddies shows obvious seasonal characteristics.Correlation analysis shows that the variation of chlorophyll in the northern hemisphere is related to eddy characteristics,while that in the southern hemisphere is mainly caused by eddy advection.A case study shows that the effects of eddies on chlorophyll change are disparate,and different mechanisms existed in different life stages.