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

1.分析了居潮锋区CTD和XBT的详细资料。(1)逆温层观测频繁，但相应的盐度分布对逆温层进行了补偿，密度分布静态稳定。(2)逆温层垂直尺度为50 ~ 80m，水平尺度为7km左右。他们被观察了几十个小时。通过对连续CTD观测的分析，推断这些逆温层是由双扩散对流驱动的不同温盐性质的水团侵入造成的。这是在野潮额区首次发现双弥漫性扩散驱动侵入的证据。(3)从观测和室内实验两方面对双侵入行为进行了分析。研究发现，无论是单层推进还是多层推进，侵入体的行为（推进速度、厚度）都存在显著差异。根据实验确定的参数，将观测到的入侵估计为单层。根据地层和侵入体厚度估算推进速度，并用于估算垂直和水平有效扩散系数，分别为10^<-4>m^21s, 10m^21s。对盐指对流进行了三维数值实验。(1)成功再现不规则构型盐指对流。(2)盐指宽度与线性稳定性理论及室内实验结果吻合良好。(3)密度项下的热盐垂直输运值略低于室内实验值。

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.