پديد آورندگان :
ماه پيكر، اميد دانشگاه علوم و فنون دريايي خرمشهر - دانشكده علوم دريايي و اقيانوسي - گروه فيزيك دريا , اشتري لركي، امير دانشگاه علوم و فنون دريايي خرمشهر - دانشكده علوم دريايي و اقيانوسي - گروه فيزيك دريا , اكبري نسب، محمد دانشگاه مازندران بابلسر - دانشكده علوم دريايي و اقيانوسي - گروه فيزيك دريا
كليدواژه :
خليج فارس , پيچك , الگوريتم هندسه برداري , مدل سازي عددي
چكيده لاتين :
Background and Objectives: Eddies are relatively large, rotating masses of water in the seas similar to tornadoes in the atmosphere and are often accompanied by large ocean currents. For example, on the sides of the Kuroshio current, there are often mesoscale eddies with a radius of ten to hundreds of kilometers. A vortex can form when the current becomes unstable, and this instability grows and causes the current to twist, and eventually, an eddy is obtained. According to previous studies, eddies move slowly and can be considered a quasi-static structure in the water column compared to the dominant currents. Because eddies can transport warm or cold water masses, properties such as temperature and salinity distributions of the basin have undergone significant changes. These changes can affect the concentration of nutrients, the spread of pollutants, and changes in sound speed in water effective. So, the study of Eddies is critical in fishing, the environment, military, and maritime industries. Methods: This study used a vector geometry algorithm based on the rotation of flow velocity vectors to identify and extract eddies in the Persian Gulf. The inputs of this algorithm, which are the horizontal components of velocity in different layers, are the result of numerical modeling of hydrodynamic circulation by the Mike model. After extracting eddies using the algorithm, their properties were investigated. Findings: The algorithm results are extracted in 25 layers with a thickness of 2 meters from the surface to a depth of 50 meters. A total of 4308 cyclonic eddies and 2860 anticyclonic eddies were identified in the surface layer, and 617 cyclonic eddies and 329 anticyclonic eddies in the lowest layer, i.e., 50 meters depth. Eddies have the shortest lifespan in summer and the longest in winter. Also, the average lifespan of cyclonic eddies is slightly longer than anticyclonic eddies in all seasons except winter. The longer the lifespan of eddies, the more they penetrate to the depths, and the longer the lifespan of eddies is observed in the surface layers. Also, in some layers, the number of eddies increases slightly compared to the upper layer, indicating the formation of eddies in the middle layers. In summer, salinity can be considered one of the signs of Eddie's presence and in winter, temperature can be viewed as an indicator for identifying eddy. With these interpretations, whenever a decrease or increase in temperature or salinity occurs radially, the possibility of vortex occurring in that area can be considered; Of course, this temperature and salinity gradient increases the probability of the event whenever it is accompanied by a rotation of the current and lasts for at least a few days. Conclusion: Persian Gulf eddies are among the rotational structures of the current in this watershed that play an essential role in the circulation, temperature-salinity change, and ecosystem. Because these structures have their complexities and the mechanism of their formation is not precisely known, the study of physical and geometric properties and characteristics leads to understanding them. In this study, the vector geometry algorithm was used to identify, extract and analyze eddies located in the Persian Gulf. After identifying the Eddies by the algorithm, their characteristics such as the average seasonal lifespan, number changes in terms of depth, their vertical structure, their seasonal distribution, and vertical profile of temperature and salinity were discussed.
