Coherent filaments at the ocean surface often appear to be transient watermass boundaries, where currents converge, surfactants accumulate, and frontal structure at depth can possibly delineate enhanced biological activity in the upper water column. Spaceborne synthetic aperture radar (SAR) permits filaments to be observed at O[1-km] resolution, but extensive coherent structures are more apparent in weaker winds. A wind speed adjustment is proposed for filaments (i.e., contiguous SAR contrasts) of at least 10 km in length. Measures of dependence (distance correlation and the linear and nonlinear components of Pearson correlation) are examined to identify a broad peak in the relationship between filament contrast and weak or moderate values of surface wind speed, where a variable wind speed exponent is employed to maximize these measures. Three locations of recent North Atlantic right whale (Eubalaena glacialis) sightings in the Gulf of St. Lawrence are sampled between 2008 and 2020 by 324 Radarsat-2 SAR scenes and 10-m wind speed from the ERA5 reanalysis. The inverse relationship between SAR contrast magnitude and wind speed is quantified, and a reduced correlation is obtained for all three domains when SAR contrast is weighted by wind speed to the power of 0.8. A more uniform emphasis on ocean surface structure within a SAR scene, or across multiple scenes, can thus be considered in the search for prey aggregations of the North Atlantic right whale.

翻译：海洋表面的相干细丝常呈现为瞬态水团边界，此处海流汇聚、表面活性物质聚集，而深层的锋面结构可能勾勒出上层水体中增强的生物活动。星载合成孔径雷达可实现对千米级分辨率的海洋细丝观测，但大尺度相干结构在较弱风速下更为显著。本文针对长度至少10公里的细丝（即连续SAR对比度）提出风速校正方法。通过分析依存性度量（距离相关系数以及皮尔逊相关系数的线性与非线性分量），识别出细丝对比度与海面风速弱-中值区间之间的宽峰关系，其中采用可变风速指数以最大化这些度量。选取圣劳伦斯湾近期三次北大西洋露脊鲸目击事件区域，基于2008至2020年间324景Radarsat-2 SAR影像及ERA5再分析10米风速数据开展采样。量化了SAR对比度幅度与风速的反比关系，当以风速的0.8次幂加权SAR对比度后，三个研究区域的相关性均呈现下降。因此，通过此类风速加权处理，可在单景或多景SAR影像中实现海洋表面结构更均匀的权重分配，从而辅助搜索北大西洋露脊鲸的猎物聚集区。