The Tides, Internal Waves, Mixing and Climate

提案号：oce0241061本提案的总体目标是努力理解海洋潮汐之间的联系，潮汐能量转化为内波，内波破碎导致的垂直混合，以及这种混合对地球气候的影响。直到最近才发现将这一系列过程联系在一起的证据，这个话题对海洋在气候中的作用有着重要的影响。破碎的内波是海洋湍流混合的主要原因。最近的研究表明，内部潮汐是混合机械能的主要来源，高达1太瓦的潮汐能在深海内部消散，远离主要陆地块的大陆架。这种能量是通过在海底地形崎岖的海洋内部产生内波，从海洋的潮汐中提取出来的。由耗散的内波能支持的混合影响了深海的温盐结构，并为驱动深海环流提供了浮力强迫。然而，目前最先进的海洋环流模型都没有考虑到这种潮汐驱动的增强垂直混合，而且缺乏正确的物理原理，这就引出了这些模型在预测当前海洋环流方面有多可靠的问题。这些模式也是气候模式的重要组成部分，它们预测未来气候变化的能力受到严重质疑。这突出表明需要改进用于研究地球气候的海洋环流模式中混合的参数化。这一建议的智力价值在于解决了一些悬而未决的问题，这些问题涉及粗糙地形上潮汐耗散和混合增强的动力学参数化及其与地球气候的关系。此外，它还试图了解潮汐强迫周期与地球气候变化之间的物理联系。这项工作的更广泛的影响将是通过更现实的气候模型（特别是社区气候系统模型）改进气候预报的社会效益，从而更准确地预测自然发生的和人为造成的地球气候变化。

ABSTRACTPI/Institution: Jayne / WHOI Proposal No: OCE-0241061The overall objective of this proposal is to work toward understanding the connections between the ocean's tides, the conversion of the tide's energy into internal waves, the vertical mixing that results from the breaking internal waves, and the impact of that mixing on Earth's climate. Evidence linking this chain of processes together has only recently been found and this topic is rife with important implications for the ocean's role in climate. Breaking internal waves are the main cause of turbulent mixing in the ocean. Recent studies have implicated the internal tides as a major source of mechanical energy for mixing, with up to 1 terawatt of tidal power being dissipated in the interior of the deep ocean, away from the continental shelves of the major land masses. This power is extracted from the ocean's tides through generation of internal waves in the ocean's interior in regions of rough seafloor topography. The mixing supported by the dissipating internal wave energy influences the thermohaline structure of the deep ocean and provides buoyancy forcing for driving circulation in the abyss. However, none of the state-of-the-art ocean general circulation models take into account this tidally driven enhanced vertical mixing, and this lack of correct physics begs the question of how reliable these models are at predicting the present ocean circulation. These models are also an important part of climate models, and their ability to predict future climate change is brought into serious question. This highlights the need for improved parameterizations of mixing in ocean general circulation models used to study the Earth's climate. The intellectual merit of this proposal is addressing some of the outstanding questions concerning the parameterization of the dynamics of enhanced tidal dissipation and mixing over rough topography and its relation to Earth's climate. Further it seeks to understand the physical linkages between the cycles in tidal forcing and changes in the earth's climate. The broader impact of this work will be the societal benefit of improved climate forecasts through more realistic climate models (in particular the Community Climate System Model) which lead to more accurate forecasts of naturally-occurring and anthropogenically-forced changes in earth's climate.