Submesoscale currents from buoyant seismic streamers (SCR-BAS)

我们提出了一个为期9个月的项目，作为英国南极调查和斯伦贝谢古尔德研究之间的现有联合项目的延伸。斯伦贝谢的船只在地球仪的许多地方进行海底和底层地理的地震调查，以评估海上石油和天然气储量。这些船只后面拖着一排宽约1公里的十几根电缆，这些电缆被称为“拖缆”，通常长6-10公里（尽管直径只有5厘米）。拖缆上装有数千个传感器（通常是水听器），用于检测来自震源的反射信号。拖缆还装有许多转向装置，可用于主动改变拖缆在水中的位置。在这个项目中，我们不使用水听器记录的地震数据，而是使用拖缆的物理信息，如位置，张力和转向力，由此可以导出洋流模型（不过，海洋密度的地震数据可能对后续研究有用，以提高我们对次中尺度过程的理解）。迄今为止，已经开发并测试了一种前向模型，以估计拖缆在被拖曳通过洋流场时的运动。这里将开发一个逆模型，以获取与拖缆有关的记录信息，特别是头端的张力以及沿着电缆的速度和角度，并推导出沿着电缆的水平无发散海流，从而提供亚中尺度（水平方向约1-10公里）的速度信息。该项目将完善，验证独立的观察和实施这一逆模型。该项目的组成部分将直接建立在NERC资助的工作基础上，这些工作是过去和现在的一些项目的一部分。这些结果将立即使斯伦贝谢受益，因为它们将为该地区的预期海流提供信息，以便计划重复调查，它们还将为NERC的一些研究项目提供信息，这些项目调查海洋中次中尺度过程的作用。

We propose a 9-month project as an extension of an existing joint project between British Antarctic Survey and Schlumberger Gould Research. Schlumberger's vessels conduct seismic surveys of the seabed and underlying geography at many locations around the globe to assess offshore oil and gas reserves. The vessels tow behind them an array about 1 km in width of a dozen cables known as "streamers", typically 6-10 km long (though only 5 cm in diameter). The streamers hold many thousands of sensors (usually hydrophones) to detect the reflected signal from a seismic source. The streamers also hold a number of steering devices, which can be used to actively modify the position of the streamer through the water. In this project we do not use the seismic data recorded by the hydrophones but instead the physical information of the streamers, such as position, tension and steering forces from which ocean current models can be derived (the seismic data of ocean density may however prove useful for follow-on studies to improve our understanding of submesoscale processes).To-date a forward model has been developed and tested to estimate the motion of streamers as they are towed through an ocean current field. Here an inverse model will be developed to take recorded information related to the streamers, in particular the tension at the head end and the velocities and angles along the cable, and to deduce the horizontal, divergence-free currents along the cable, thus providing velocity information at the submesoscale (approximately 1-10 km in the horizontal). The project will refine, validate against independent observations and implement this inverse model. Components of the project will directly build off NERC-funded work conduced as part of a number of past and present projects. The results will be of immediate benefit to Schlumberger as they will provide information for expected currents in the area with which to plan repeat surveys and they will also feed into a number of NERC research projects investigating the role of submesoscale processes in the ocean.