Quantification of the Growth and Decay of Wind Driven Gravity-Capillary Waves

风驱动重力毛细波的增长和衰减的量化

• 批准号: 0647819
• 负责人: Xin Zhang
• 金额: $ 34.58万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0647819&HistoricalAwards=false
• 关键词: Quantification; Growth; Decay; Wind; Driven

OCE-0647819Wind wave generation theories, such as the critical layer and non-separated sheltering, suggest that energy transfer takes place within a thin critical-layer or inner region very close to the water surface. The viscous surface stress also becomes important as wavelength becomes short when the viscous sub-layer is comparable with critical layer or inner region. All these calculations are based on a smooth wave surface. However, short ocean waves ( 30 cm) are often found to have a train of parasitic capillaries on their forward phase. The critical layers, or inner region, associated with these short wind waves are so close to the water surface that the layers become ill-defined aerodynamically due to the parasitic capillaries. The role that parasitic capillaries play in generating short wind waves is not clear, which casts doubt on extending these theories to very short ocean wind waves. The existing measurements of initial wave growth rate are not conclusive because initial waves are too small to carry a significant amount of parasitic capillaries. The dissipation of mechanically generated short waves due to parasitic capillaries has been experimentally measured. The PI proposes to continue the work to further experimentally quantify the growth rate of short wind waves and investigate possible role of parasitic capillaries in wind wave growth. The experimental observations may further be synthesized to infer stress and energy balance for a coupled ocean wind-wave system, validating some of the fundamental hypotheses of ocean wave spectrum theories.Intellectual merit: It has been known since ancient times that oil films dampen surface waves when spread on the surface of rough seas. One of the arguments is that by suppressing the capillary waves, surface films reduce the aerodynamic roughness, which in turn lessens the energy input from the wind. Yet the role of capillary waves in wind wave generation and dissipation is still not clear today. Ocean short wave spectral is important to remote sensing ocean wind. Similar forms of ocean wind spectrum have been derived from theories based on very different assumptions of energy flux balances. Through observations of this study, the hypotheses of various wind wave theories can be tested. Short wind waves are of great importance in air-sea interchanges and remote sensing. Smaller-scale interfacial motions and the near-surface boundary layers play a central role in transferring momentum, heat and gas between the oceans and the atmosphere. Measuring and understanding the complex surface processes is central to improving our capabilities of forecasting the world's weather and climate. Techniques based on microwave backscattering from short ocean waves, such as scatterometer determination of ocean wind stress, have demonstrated the capability to monitor global wind. Quantifying the short wind wave growth rate will further potentially improve the accuracy of remote ocean wind measurements.Broader impacts: This study will have an impact on broader science, as well as economic and social areas. Commercial navigation, natural and human-caused disaster relief will all potentially benefit from improving the monitoring and forecasting of the world oceans. The proposed activity will involve direct training of a graduate student and undergraduate students. In assisting air-sea interaction exhibitions at the Birch Aquarium at Scripps, an important scientific aspect of global climate change will be demonstrated to the public.

OCE-0647819风浪生成理论，如临界层和非分离遮蔽，表明能量传递发生在非常接近水面的薄临界层或内部区域内。当粘性子层与临界层或内部区域相当时，随着波长变短，粘性表面应力也变得重要。所有这些计算都是基于光滑的波浪表面。然而，短的海浪（30厘米）经常被发现有一列寄生毛细血管在其前进阶段。与这些短风浪相关的临界层或内部区域非常接近水面，以至于由于寄生毛细管，这些层在空气动力学上变得不明确。寄生毛细血管在产生短风浪中所起的作用尚不清楚，这使人们对将这些理论扩展到非常短的海洋风浪产生了怀疑。现有的初始波增长率的测量是不确定的，因为初始波太小，携带大量的寄生毛细血管。机械产生的短波由于寄生毛细管的耗散已被实验测量。PI建议继续开展工作，以进一步通过实验量化短风浪的增长率，并研究寄生毛细血管在风浪增长中的可能作用。实验观测结果可以进一步综合推断应力和能量平衡的耦合海洋风浪系统，验证海浪谱theories.智力优点的一些基本假设：它已经知道，自古以来，油膜阻尼表面波时，在汹涌的海面上蔓延。其中一个论点是，通过抑制毛细波，表面膜降低了空气动力学粗糙度，这反过来又减少了来自风的能量输入。然而，毛细波在风浪生成和消散中的作用至今仍不清楚。海洋短波谱是海洋风遥感的重要内容。类似形式的海洋风谱是从基于非常不同的能量通量平衡假设的理论中推导出来的。通过本研究的观测，可以检验各种风浪理论的假设。短风浪在海气交换和遥感中具有重要意义。小规模的界面运动和近地表边界层在海洋和大气之间的动量、热量和气体传递方面发挥着核心作用。测量和了解复杂的地表过程对于提高我们预测世界天气和气候的能力至关重要。基于短海浪微波后向散射的技术，例如用散射仪测定海洋风应力，已证明有能力监测全球风。量化短风浪增长率将进一步提高远程海洋风测量的准确性。更广泛的影响：这项研究将对更广泛的科学以及经济和社会领域产生影响。商业航行、自然灾害和人为灾害救济都可能受益于改善对世界海洋的监测和预报。拟议的活动将涉及直接培训一名研究生和一名本科生。在协助斯克里普斯桦树水族馆举办的海气相互作用展览中，将向公众展示全球气候变化的一个重要科学方面。