Freshwater lenses (FWLs) deposited by rain exhibit local anomalies in surface salinity and temperature. The resulting patchiness in near-surface density and sea surface temperature influence upper ocean dynamics and air-sea fluxes of heat. Understanding lens formation and evolution has been a focus of recent observational and modeling efforts. The work presented here integrates near-surface ocean and atmosphere time series with remote sensing of sea surface disturbances (X-band radar) to describe properties and kinematics of FWLs in the equatorial Indian Ocean. Twenty-eight FWLs were observed with diverse temperature-salinity properties and structure. Fresh salinity anomalies were as large as −1.35 psu at 3 m depth. Associated temperature anomalies ranged from −0.80 to +0.59°C. Ship-based radar imagery allowed quantification of propagation speeds of 10 FWL fronts. In the reference frame of the moving fluid, the observed speeds are consistent with the linear long wave speed of . These results offer a novel perspective on the evolution of FWLs as gravity currents whose dynamics need to be properly accounted for to assess lens longevity, including persistence of salinity and temperature anomalies, as well as influences on air-sea interaction.

中文翻译：

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淡水透镜锋在赤道印度洋中作为浮力流传播

由雨水沉积的淡水透镜体 (FWL) 在地表盐度和温度方面表现出局部异常。由此产生的近地表密度和海面温度的不均匀性影响上层海洋动力学和海气热通量。了解透镜的形成和演化一直是最近观察和建模工作的重点。这里介绍的工作将近地表海洋和大气时间序列与海面扰动的遥感（X 波段雷达）相结合，以描述赤道印度洋 FWL 的特性和运动学。观察到 28 个具有不同温度-盐度特性和结构的 FWL。在 3 m 深度，新鲜盐度异常高达 -1.35 psu。相关的温度异常范围为 -0.80 至 +0.59°C。舰载雷达图像允许量化 10 个 FWL 前沿的传播速度。在运动流体的参考系中，观察到的速度与线性长波速度一致. 这些结果为 FWL 作为重力流的演变提供了新的视角，需要正确考虑其动力学以评估透镜寿命，包括盐度和温度异常的持续性，以及对海气相互作用的影响。