报告题目：Mixing from Tides and Winds and Its Impacts

报告人：Prof. Robin Robertson，Xiamen University Malaysia

报告摘要：Ocean mixing plays several major roles in the ocean circulation and climate system. It maintains the stratification, drives the global overturning circulation, distributes nutrients and larvae for biological productivity and fisheries, redistributes heat and salt, and influences climate dynamics. However, this important process is one of the most prominent problems in physical oceanography and climate research today. The major difficulty is that many different mechanisms cause mixing, from large scale processes such as eddies and internal waves to small scale processes such as overturns and wind waves. Biological processes cause mixing, with significant contributions coming from even the smallest organisms, through the daily migration of zooplankton from the deep ocean to the surface.

Mixing is not evenly spread through the world’s oceans, but is localized in specific “hot” spots, with mixing in these “hot” spots observed to be a hundred times higher than background values. Additionally, it varies in time, e.g. tidal mixing follows the spring-neap and daily tidal cycles. As a result, both measuring and simulating mixing are difficult, since the observations have to both be in the right spot at the right time.  The problem with simulating mixing is that many of the processes are much smaller than the grid size, so they are parameterized. The parameterizations are supposed to reproduce the observed mixing, but sometimes they don’t.

My research involves mixing, both simulating mixing for certain situations and in evaluating the performance of how mixing is represented in the models. I have evaluated several mixing parameterizations for both wind-driven and tidal mixing.  One of the most widely used scheme overmixes for both of these cases. So, there is room for improvement of how the mixing is handled in models. That said, they do a reasonable job of reproducing tidal mixing and the mixed layer depth. But more practically, I have simulated internal tides in the Coral, Tasman, Antarctic and Indonesian seas. The Indonesian seas are most relevant to Malaysia and are known as a major mixing region. The Indonesian “Mix-Master” converts Pacific waters into cooler, fresher Indonesian Throughflow water. The importance of the Indonesian seas is that they impact precipitation and temperatures in Southeast Asia, China, and Australia [Nicholls, 1995] and are a critical link in the global conveyor belt.

报告时间：2018年8月29日（周三）9:30

报告地点：5号楼511会议室