NSFGEO-NERC Scattering of ocean surface gravity waves by submesoscale turbulence

次中尺度流对海洋表面重力波(SGW)的随机散射、折射和聚焦导致了波场的空间调制--“斑块”。斑块的一个特征是有效波高HS在水平尺度上的变化在10到100公里的范围内和几个小时到一天的时间尺度上变化高达30%；这些尺度反映了亚中尺度洋流的变化，并且比传统上认为控制HS的时空变异性的SGW的风应力强迫的变化要小得多。因此，斑块对SGW的建模和预测及其对海洋环流的影响构成了重大挑战。该项目将通过开发次中尺度湍流散射SGW的新统计模型来应对这一挑战。我们将使用这些模型来解释斑块可变性的主要特征，包括最近发现的HS功率谱和亚中尺度动能谱之间的关系，并开发亚中尺度湍流对SGW散射的参数化，我们将将其纳入WaveWatch III。HS的空间和时间波动反映在SGW场的其他属性中，包括斯托克斯速度，因此控制SGW强迫电流的波浪平均涡旋和Stokes-Coriolis力。我们将研究波浪和平均流之间的相互作用在斑块时间和空间尺度上很强的假设，并开发适合这些尺度的新的建模工具。

Random scattering, refraction and focussing of ocean surface gravity waves (SGWs) by submesoscale currents result in spatial modulation - "patches'' - in the wave field. A signature of patches is that the significant wave height Hs varies by as much as 30% on horizontal scales in the range 10 to 100 km and time scales of a few hours to a day; these scales reflect those of submesoscale currents and are much smaller than those of the wind-stress forcing of SGWs which is traditionally assumed to control the spatio-temporal variability of Hs. As a result, patches pose a major challenge for the modelling and prediction of SGWs and of their impact on the ocean circulation. This project will tackle this challenge by developing new statistical models of the scattering of SGWs by submesoscale turbulence. We will use these models to explain the main features of patch variability, including a recently discovered relation between the power spectrum of Hs and the submesoscale kinetic energy spectrum, and to develop a parametrization of SGW scattering by submesoscale turbulence that we will incorporate into WAVEWATCH III.Spatial and temporal fluctuations in Hs are reflected in other properties of the SGW field including the Stokes velocity, and hence the wave-averaged vortex and Stokes-Coriolis forces which control the forcing of currents by SGWs. We will investigate the hypothesis that the interaction between waves and mean flows is strong on patch time and space scales, and develop new modeling tools tailored to these scales.