The spatiotemporal features of submesoscale processes （SMPs） in the northeastern South China Sea （SCS） are analyzed based on a high-resolution simulation from 2009 to 2012. The simulation results show that the SMP...The spatiotemporal features of submesoscale processes （SMPs） in the northeastern South China Sea （SCS） are analyzed based on a high-resolution simulation from 2009 to 2012. The simulation results show that the SMPs with a vertical relative vorticity that matches the local planetary vorticity are ubiquitous in the upper ocean of the northeastern SCS. The SMPs distribution shows an asymmetry due to centrifugal instability, with stronger positive vorticity than negative vorticity. Meanwhile, the SMPs demonstrate an obvious seasonal variation. The SMPs are strong and active in winter but weak and inactive in summer. An investigation of the SMPs generation mechanisms reveals that flow straining and mixed layer depth account for this seasonal variation. The strong flow straining and deep mixed layer depth in winter favor the SMP generation via frontogenesis and mixed layer instability.展开更多
The unbalanced submesoscale motions and their seasonality in the northern Bay of Bengal(BoB)are investigated using outputs of the high resolution regional oceanic modeling system.Submesoscale motions in the forms of f...The unbalanced submesoscale motions and their seasonality in the northern Bay of Bengal(BoB)are investigated using outputs of the high resolution regional oceanic modeling system.Submesoscale motions in the forms of filaments and eddies are present in the upper mixed layer during the whole annual cycle.Submesoscale motions show an obvious seasonality,in which they are active during the winter and spring but weak during the summer and fall.Their seasonality is associated with the mixed layer instability that depends on the mixed layer depth(MLD).During the winter,the MLD provides a much greater reservoir of the available potential energy,which promotes mixed layer instability to develop active submesoscale motions.The variations of MLD are likely modulated by the larger scale motions and the influxes of freshwater.Further investigations imply that the MLD and the stratified barrier layer are combined to determine the vertical structure of the submesoscale motions.The shallow MLD and strong stratification below during the summer and fall seem to prevent the downward extension of submesoscale motions.But in spring when the weak stratification exists,the penetration depth exceeds the base of the barrier layer.展开更多
基金The National Key Research and Development Program of China under contract No.2017YFA0604103the National Basic Research Program(973 Program)of China under contract No.2014CB745003+1 种基金the National Natural Science Foundation of China under contract No.91628302the Startup Foundation for the Introducing Talent of the Nanjing University of Information Science and Technology under contract No.2243141601059
文摘The spatiotemporal features of submesoscale processes （SMPs） in the northeastern South China Sea （SCS） are analyzed based on a high-resolution simulation from 2009 to 2012. The simulation results show that the SMPs with a vertical relative vorticity that matches the local planetary vorticity are ubiquitous in the upper ocean of the northeastern SCS. The SMPs distribution shows an asymmetry due to centrifugal instability, with stronger positive vorticity than negative vorticity. Meanwhile, the SMPs demonstrate an obvious seasonal variation. The SMPs are strong and active in winter but weak and inactive in summer. An investigation of the SMPs generation mechanisms reveals that flow straining and mixed layer depth account for this seasonal variation. The strong flow straining and deep mixed layer depth in winter favor the SMP generation via frontogenesis and mixed layer instability.
基金The National Key R&D Program of China under contract No.2018YFA0605702the National Natural Science Foundation of China under contract Nos 41876002 and 41776002。
文摘The unbalanced submesoscale motions and their seasonality in the northern Bay of Bengal(BoB)are investigated using outputs of the high resolution regional oceanic modeling system.Submesoscale motions in the forms of filaments and eddies are present in the upper mixed layer during the whole annual cycle.Submesoscale motions show an obvious seasonality,in which they are active during the winter and spring but weak during the summer and fall.Their seasonality is associated with the mixed layer instability that depends on the mixed layer depth(MLD).During the winter,the MLD provides a much greater reservoir of the available potential energy,which promotes mixed layer instability to develop active submesoscale motions.The variations of MLD are likely modulated by the larger scale motions and the influxes of freshwater.Further investigations imply that the MLD and the stratified barrier layer are combined to determine the vertical structure of the submesoscale motions.The shallow MLD and strong stratification below during the summer and fall seem to prevent the downward extension of submesoscale motions.But in spring when the weak stratification exists,the penetration depth exceeds the base of the barrier layer.
