Advances in the understanding and modelling of surface currents have revealed the importance of internal waves, mesoscale and submesoscale features. Indeed all these features should have a large influence on wind waves and in particular on wave heights. Still, the quantitative impact of currents on waves is not well known due to the complexity of the random wave fields and currents that are found in the ocean, and the lack of observations of both currents and waves at scales shorter than 150km. Here we compare novel satellite altimetry data and state of the art phase‐averaged numerical wave models forced both by wind and currents. Currents used are taken from the oceanic model CROCO, run at high resolution. The influence of current field resolution is investigated by applying Gaussian filters of different width to that same high resolution current field. We find that a numerical wave model that uses currents with resolutions of ∼30km or less and a directional resolution of 7.5°, can provide accurate representations of the significant wave height gradients found in the Agulhas current. Using smoother current fields such as derived from altimeters measurements alone, coarse directional spectral resolution or larger directional spread of the wave model, generally underestimates gradients and extreme wave heights. Hence, satellite altimetry provides high resolution wave height with a gradient magnitude that is highly sensitive to underlying surface current gradients, at resolutions that may not be resolved by today's altimeters measurements. This is demonstrated here for relatively steady currents averaged over 3 years.

中文翻译：

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地表电流和重要的波高梯度：Agulhas当前区域中的匹配数值模型和高分辨率高度计波高

对表面电流的理解和建模的进步揭示了内部波，中尺度和亚中尺度特征的重要性。实际上，所有这些特征都应该对风波，特别是波高产生很大的影响。然而，由于随机波场和海洋中发现的洋流的复杂性，以及缺乏对小于150 km的洋流和海浪的观测，洋流对海浪的定量影响尚不为人所知。在这里，我们比较了新颖的卫星测高数据和由风和流共同作用的最先进的相位平均数值波模型。所使用的电流取自高分辨率运行的海洋模型CROCO。通过将不同宽度的高斯滤波器应用于相同的高分辨率电流场，研究了电流场分辨率的影响。我们发现，使用分辨率约为30km或更小的电流且方向分辨率为7.5°的电流的数值波模型可以准确表示Agulhas电流中的重要波高梯度。使用更平滑的电流场（例如仅从高度计测量得出的结果），粗略的方向光谱分辨率或较大的波模型方向扩展，通常会低估梯度和极端波高。因此，卫星测高仪提供的高分辨率波高的梯度幅度对下层表面电流梯度高度敏感，其分辨率可能是当今测高仪无法解决的。