Collaborative Research: Forcing, Energy Flow and Impacts of Oceanic Infragravity Waves

该项目将研究周期从30秒到一小时的海洋表面重力波，即“亚重力”波段。现有的海底压力，地磁场，大气压力和海洋重力波的观测将与频谱技术进行分析，以检查的机制（源），通过它的能量被用来产生亚重力波（IGW）。来源包括海啸和涌浪与海岸线的相互作用，海洋表面潮汐，以及以前在太阳风，地震，地磁，气压和电离层数据中观察到的太阳正常模式的能量。IGWs可以是不同现象之间的重要连接器，将源的可变性与地球正常模式的激发，南极洲冰架的弯曲，对深海混合的贡献，以及在高度计数据中添加“噪声”。如果理解和建模适当的IGW，这样的噪音可以被最小化，以改善这样的测高数据。此外，该项目将有助于培养一名物理海洋学研究生，培养下一代科学家，使他们有能力探索我们的星球，以实现一个更加环境安全的未来，随着技术的发展，可以更多地观测地球和地外变量，如太阳风和海底压力，新的信息使人们对不同现象之间的高度联系有了深入的了解。长期以来，人们对所谓的亚重力波（IGW;周期为30秒至1小时的海洋表面重力波）感兴趣，这是因为它们受到海岸海啸和涌浪（重力波周期小于30秒）的激发。被迫在海岸的IGW是一个因素，加剧了海啸和涌浪造成的洪水和侵蚀。在开阔的海洋中，IGW较弱，但已被发现是产生显着现象的能量的意想不到的途径，例如地球正常模式的连续激发，这些信号现在经常用于探索地球结构和组成的细节。但是，关于IGW的各种能量来源以及这种能量对亚重力波（即，能量的途径）。主要研究人员最近证明了两种新能源的存在：海洋表面潮汐和太阳正常模式。该项目将：（1）获得更多的潮汐和太阳能进入IGW路径的观测证据;以及（2）量化这两个源作为频率、时间段（例如，季节; 11年太阳周期）和位置（例如，地磁纬度;边缘海与开阔洋）。这些源对IGW的相对贡献，特别是它们的空间分布，是理解IGW影响及其与上述其他现象联系的关键特征。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will examine oceanic surface gravity waves with periods from 30 seconds to an hour, the ‘infragravity’ waveband. Existing observations of ocean bottom pressure, geomagnetic field, atmospheric pressure, and ocean gravity waves will be analyzed with spectral techniques to examine the mechanisms (sources) by which energy is used to generate infragravity waves (IGW). Sources include the interactions of tsunami and swell with coastlines, ocean surface tides, and energy from the solar normal modes that have previously been observed in solar wind, seismic, geomagnetic, barometric, and ionospheric data. IGWs can be important connectors between disparate phenomena, connecting source variability to the excitation of earth’s normal modes, flexing of ice shelves in Antarctica, contribution to mixing in the abyssal ocean, and adding ‘noise’ in altimeter data. If understood and modeled appropriately as IGW, such noise could be minimized, to improve such altimetry data. In addition, this project will contribute to the education of a graduate student in physical oceanography building the next generation of scientists capable of exploring our planet for a more environmentally secure future.As technology has expanded the availability of observations of terrestrial and extra-terrestrial variables, such as the solar wind and pressure at the bottom of the oceans, new information has yielded insight into how highly connected disparate phenomena can be. Of longstanding interest are so-called infragravity waves (IGWs; oceanic surface gravity waves at periods of 30 seconds to an hour) due to their excitation by tsunamis and swell (gravity wave periods less than 30 seconds) at the coasts. IGWs forced at the coasts are a factor that enhances flooding and erosion by tsunamis and swell. In the open ocean, IGWs are weaker, but have been found to be unexpected pathways for energy that engender remarkable phenomena, such as the continuous excitation of Earth's normal modes, signals that are now regularly used to explore the details of Earth's structure and composition. But understanding is limited regarding the various sources of energy for the IGWs, and the mechanisms this energy contributes to infragravity waves (i.e., the energy pathways). The principal investigators recently demonstrated the existence of two new energy sources: ocean surface tides and solar normal modes. This project will: (1) acquire more observational evidence of the tidal and solar energy pathways into the IGWs; and, (2) quantify the contributions of these two sources as a function of frequency, time period (e.g., season; 11-yr solar cycle) and location (e.g., geomagnetic latitude; marginal seas vs. open ocean). The relative contributions of these sources to IGWs, and especially their spatial distribution, are crucial characteristics for understanding the impacts of IGWs and their connections to the other phenomena noted above.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.