Isopycnal Intrusions in Doubly Diffusive Fluids

[0236304] stern2维双扩散侵入将在正面模型中进行分析和数值研究。对于指状有利的垂直温度和盐度梯度（盐度向上增加），小尺度通量将由先前获得的（数值）校准参数化。将有限横向宽度模型应用于二维侵入性不稳定的横向矿化度变化的最小临界值。对于超临界侧向盐度变化，特征函数将初始化一个数值积分，该积分将给出平均侧向梯度的修正和等压翻转的条件。在横向有界的锋面模式中，还将研究从下方加热的稳定盐梯度的情况，并且侵入性不稳定性的垂直尺度将与在威德尔海观测到的最小温跃层台阶有关。在这些步骤中向上的热通量可能有助于维持在南极冰中观测到的可能影响大气气候的大间隙（冰裂谷）。该项目将有助于我们理解水团的水平混合，通过使用非常精细和精确的盐指参数化来模拟发生在密度补偿热盐锋上的侵入，并回答诸如首选侵入规模和震级等问题。这项研究将以报告和出版物的形式提供给气候模拟界，以便将研究结果纳入一般的海洋环流模式。此外，博士后和博士生将获得使用最先进的科学计算设备和技术来解决具有重要实际意义的流体动力学问题的宝贵经验。PI还将参加伍兹霍尔海洋研究所的地球物理流体动力学（GFD）暑期项目。

0236304 SternTwo dimensional doubly diffusive intrusions will be investigated analytically and numerically in a frontal model. For the case of finger favorable vertical temperature and salinity gradients (salinity increasing upward) the small scale fluxes will be parameterized by previously obtained (numerical) calibrations. Application to the finite lateral width model will give a minimum critical value of the lateral salinity variation for the onset of a two-dimensional intrusive instability. For supercritical lateral salinity variation the eigenfunctions will initialize a numerical integration which will give the modification of the mean lateral gradients and the condition for isopycnal overturns. The case of a stable salt gradient heated from below will also be examined in a laterally bounded frontal model, and the vertical scale of the intrusive instability will be related to the smallest thermocline steps observed in the Weddell Sea. The upward heat flux in these steps may help to maintain the large gaps (polynyas) observed in the Antarctic ice which could affect the atmospheric climate.This project will contribute to our understanding of the horizontal mixing of water masses by using a very elaborate and precise salt finger parameterization to model the intrusions occurring on a density-compensated thermohaline front and answer questions such as preferred intrusion scales and magnitudes. This research will be made available to the climate modeling community with presentations and publications so that the results can be incorporated into the general ocean circulation models. In addition, the post doc and Ph.D. student will gain invaluable experience in using state-of-the art scientific computational equipment and techniques to solve fluid dynamical problems of significant practical interest. The PI will also participate in the Summer Program in Geophysical Fluid Dynamics (GFD) at Woods Hole Oceanographic Institution..