Submesoscale currents from buoyant seismic streamers (SCR-BAS)

我们提出了一个为期9个月的项目，作为英国南极调查局和斯伦贝谢·古尔德研究公司现有联合项目的延伸。斯伦贝谢公司的船只对全球许多地方的海床和基础地理进行地震勘测，以评估近海石油和天然气储量。这些船只身后拖着一排约1公里宽的电缆，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)。拖缆装有数千个传感器(通常是水听器)，用来探测来自震源的反射信号。拖缆还装有多个转向装置，可以用来主动修改拖缆在水中的位置。在这个项目中，我们没有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，根据这些信息可以推导出海流模型(然而，海洋密度的地震数据可能会被证明对后续研究有用，以提高我们对亚中尺度过程的理解)。到目前为止，已经开发了一个正演模型，并进行了试验，以估计拖缆在海流场中拖曳时的运动。在这里，将开发一个反向模型，以获取与拖缆有关的记录信息，特别是头端的张力以及沿缆线的速度和角度，并推导出沿缆索的水平、无发散的水流，从而提供亚中尺度(水平约1-10公里)的速度信息。该项目将根据独立的观测结果进行改进和验证，并实施这一逆模型。该项目的组成部分将直接建立在国家核研究中心资助的工作的基础上，这些工作是过去和现在一些项目的一部分。这些结果将对斯伦贝谢产生立竿见影的效果，因为它们将为该地区预期的洋流提供信息，以便计划重复调查，它们还将提供给国家海洋研究中心的一些研究项目，这些项目调查次中尺度过程在海洋中的作用。

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.