报告题目：Near Surface Turbulence and the Air-Sea Gas Transfer Velocity
时间：2014年6月9日（星期一）上午9:30
地点：安中大楼A322
报告人：廖谦，副教授，美国威斯康星大学密尔沃基分校，土木与环境工程学系系主任
内容概要：Gas exchange across the air-sea interface is an important process in atmosphere-aquatic coupled systems and is a crucial factor that affects global biogeochemical cycles and climate. Recent studies suggested that under low to moderate wind conditions without bubble entrainning wave breaking, the air-sea gas transfer velocity can be mechanistically parameterized by the near-surface turbulence, following the small-scale eddy model (SEM) or the surface divergence model (SDM). Field measurements supported SEM in a variety of environmental forcing systems. However, the empirically determined model coefficient scattered over a wide range. Here we present the first field measurement of the near-surface dissipation rate with a novel floating PIV system on Lake Michigan. Meanwhile CO2 flux was measured simultaneously with a floating gas chamber. Measured results indicated that model coefficient was not a universal constant. Regression analysis showed that it scaled linearly with the logarithm of the dissipation rate with data described here as well as from other published results measured in a similar environment. It also showed that the model coefficient can scale linearly with the Reynolds number. Findings suggest that larger eddies are also important parameters and the dissipation alone may not be adequate to determine the gas transfer velocity.
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水文与水资源工程研究所
2014年6月4日