The Role of Double Diffusive Convection in the Mixing process of the Ocean

1.分析了Oyashio Frontal地区的详细CTD和XBT数据。(1)逆温层经常被观察到，但相应的盐度分布补偿，由此产生的密度分布是静态稳定的。(2)逆温层垂直尺度为50- 80 m，水平尺度约为7 km。他们被观察了几十个小时。通过对连续CTD观测资料的分析，推测这些逆温层是由双扩散对流驱动的具有不同温盐性质的水团侵入造成的。这是双扩散扩散驱动的侵入体在Oyashio锋面地区的第一个证据。(3)从观测和室内实验两个方面对双入侵行为进行了分析。研究发现，无论是单层还是多层侵入体，其侵入行为（推进速度、厚度）都有很大差异。观察到的入侵估计为一个单一的layr从实验确定的参数。根据盐岩的分层和厚度估算了盐岩的推进速度，并以此估算了盐岩的垂直和水平有效扩散系数，分别为10 <-4>m^21s和10 m^21s。(1)盐指对流具有不规则的配置被成功地再现。(2)盐指宽度与线性稳定性理论和室内实验结果吻合较好。(3)垂直输运的热量和盐的密度项略低于室内实验。

1.Detailed CTD and XBT data at the Oyashio Frontal region were analyzed.(1) Temperature inversion layrs were frequently observed, but are compensated by the corresponding salinity distribution, and resulting density distributions were statically stable.(2) Temperature inversion layrs had 50-80m scales in the vertical, and about 7km in the horizontal. They were kept observed for several tens of hours. From the analysis of continuous CTD observation, these inversion layrs are inferred to be caused by the intrusion of water masses having different temperature-salinity properties driven by the double diffusive convection. This is the first evidence of double diffusive diffusively driven intrusions in the Oyashio frontal regions.(3) The behavior of double intrusion was analyzed more from the observations and laboratory experiment. It is found that there were substantial differences in the behavior of intrusions (advancing velocity, thickness) whether they advance as a single layr or multiple layrs. Observed intrusion was estimated as a single layr from the experimentally determined parameters. Advancing velocity was estimated from the stratification and the thickness of intrusion, and is used for estimating vertical and horizontal effective diffusivities, and are 10^<-4>m^21s、10m^21s, respectively.2.Three dimensional numerical experiment on the salt finger convection was done.(1) Salt finger convection having irregular configuration was successfully reproduced.(2) The width of salt finger agress well with the linear stability theory and laboratory experiments.(3) Vertical transport of heat and salt in density terms are slightly lower than those from laboratory experiment.