讲座报告 Seminar
Luncheon Seminar #93: Exploring the role of small-scale thermohaline structure on mixing and transport in the ocean  
【时间 Time】:2018-2-26 (星期一) 10:50am-11:50am    【浏览次数 Count】:542   【发布时间 Updated】:2018-2-20
【地点 Venue】:A3-206 Zhou Long Quan Building
【主讲人 Speaker】:Yihua Li,博士   
【来访单位 Institution】:School of Mathematics and Statistics & Climate Change Research Centre, University of New South Wales,澳大利亚     Australia
【邀请人 Host】:Zhiyu Liu      【联络人 Contact】:Fangtao Zhang
Abstract:
In the first part of this talk, double-diffusive interleaving is examined as it progresses from a linear instability towards finite amplitude. We examine the “finger” and “diffusive” instability types and ask whether a steady state is possible. We find that the strength of the fluxes across the “diffusive” interfaces must be many times stronger relative to the corresponding fluxes across the “finger” interfaces than is indicated from existing flux laws as derived from laboratory experiments. The total effect of the interleaving motion on the vertical fluxes of heat and of salt is calculated for the steady-state solutions.
The remainder of the talk proposes a method to address the limited spatial resolution of ocean models. Horizontal eddy fluxes of heat and other scalar quantities in the ocean are due to correlations between the horizontal velocity and tracer fields. However, the limited spatial resolution of ocean models means that these correlations are not fully resolved using the velocity and temperature evaluated on the model grid. We derive a method for estimating the horizontal flux due to spatially unresolved spatial correlations, based on calculating an additional non-divergent velocity to advect all scalar variables. The sum of the Eulerian-mean velocity and this extra advection we call the Horizontal Residual Mean velocity. The calculation of the extra advection is based on the depth-integrated horizontal transport from the seafloor to the density surface whose spatially averaged height is at the height of the calculation. We find that in the Southern Ocean this new HRM advection accounts for 0.2PW of meridional heat flux.
Bio:
Yuehua currently works as a research assistant at the School of Mathematics and Statistics, University of New South Wales. She has completed her Ph.D. degree of Applied Maths specialising in Physical Oceanography and Ocean Modelling.
Her research interests are in fluid dynamics, ocean mixing processes and ocean model improvement. During her Ph.D. studies, she investigated the steady state solutions for a double diffusive interleaving model which incorporated experimental interfacial flux laws. Moreover, she derived a method to approximate the spatial correlation induced water and tracer transports, which are often missed due to the limited spatial resolution of ocean models. She has also gained knowledge and skills in modifying ocean models and machine learning. Therefore, she is currently working on implementing her method, which calculates the spatial correlation induced transports, into Modular Ocean Model 6.

--------------------------------------------------------------------------
* 听完报告后可以领取简易午餐。

* 请老师同学们访问MEL网页(http://mel.xmu.edu.cn/lecture.asp?id=1),在本次午餐会的“报名”一栏填写信息并提交。

* 本讲座将发布当天仅开放给科研人员、技术人员、博士后、访问学者等教师优先报名,第二天起开放给全体师生报名。学生应在规定时间内报名,如提前以教师的名义报名,将导致报名无效。

* 本周五下午4点为截止报名时间,总报名人数限制在100名以内。如未及时报上名,可于12:00直接到场听报告。如已报名但因事不能参加,也请在周五下午4点前告知。

* 午餐会一如既往地欢迎大家的关注,如有兴趣做讲座的老师请联系。