Development of GNSS-Acoustic Surveying for Shallow Water

浅水 GNSS 声学测量的发展

• 批准号: 2216876
• 负责人: Mark Zumberge
• 金额: $ 20.84万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2216876&HistoricalAwards=false
• 关键词: Development; GNSS; Acoustic; Surveying; Shallow

Plate tectonics, also known as continental drift, is the process where parts of the earth’s crust that make up continents and ocean basin seafloor move slowly around the globe at a few inches per year. On land, these motions can be detected with precise GPS measurements. However GPS (also called GNSS for “Global Navigation Satellite Systems”) signals cannot penetrate seawater. Consequently an alternative means must be invoked to detect tectonic motion of the seafloor. An established method uses a platform on the sea surface (such as a ship or buoy) whose position is simultaneously observed with GPS and sonar. The positions of seafloor receivers can be determined by measuring the travel time of sonar pulses between them and the GPS-navigated surface platform. The method has been developed with seafloor receivers designed to reside in the deep ocean – 1000 meters or greater beneath the surface, where they are safe from disturbance by human activity. However much of the interesting scientific targets for detecting seafloor tectonic motion are in shallower water – a few hundred meters deep. This research project aims to develop a protective seafloor structure that keeps a receiver safe from trawl fishing (which would otherwise compromise the survey). The GNSS-Acoustic method relies on an assumption that the sound speed velocity structure in the ocean is one dimensional, dependent only on depth. Over long times (days) this is true on average. With this assumption, the center coordinates of an array of acoustic transponders positioned symmetrically around a sea surface interrogator can be determined with cm level accuracy in a global reference frame even with imperfect knowledge of the details of the one-dimensional sound velocity profile. In shallow water, sound velocity variations are less important because the acoustic range is smaller. This should remove the need for an array of transponders – just one should suffice. However the risk from trawling remains. The project’s dual aim is to 1) determine the accuracy with which a single transponder’s coordinates can be determined up to 300 m water depth with a circling Wave Glider interrogator and 2) test the design of a trawl-resistant structure that can house a single transponder, free from disturbance from anthropogenic interactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

板块构造，也称为连续漂移，是地壳的一部分构成连续的和海盆海底，每年以每年几英寸的速度在全球范围内缓慢移动。在陆地上，可以通过精确的GPS测量来检测这些运动。但是，GPS（也称为“全球导航卫星系统”的GNSS）信号无法穿透海水。因此，必须调用一种替代手段来检测海底的构造运动。一种已建立的方法使用在海面（例如船或浮标）上的平台，该平台仅在GPS和Sonar中观察到其位置。海底接收器的位置可以通过测量它们之间的声纳脉冲的旅行时间与GPS散布的表面平台来确定。该方法是用旨在居住在深海的海底接收器开发的 - 在地面以下1000米或更大，在那里它们可以免受人类活动的干扰。但是，检测海底构造运动的许多有趣的科学目标都在较浅的水中 - 深几百米。该研究项目旨在开发受保护的海底结构，以使接收器免受拖网捕捞的影响（否则这将损害调查）。 GNSS-声学方法取决于一个假设，即海洋中的声速速度结构是一个维度，仅取决于深度。在长期（天）中，这平均是正确的。有了这个假设，即使对一维声音速度曲线的细节，也可以在全球参考框架中以CM级别的准确性来确定一系列声音转发器阵列的中心坐标。在浅水中，声音速度变化不太重要，因为声学范围较小。这应该消除对一系列应答器的需求 - 只有一个就足够了。但是，拖网的风险仍然存在。该项目的双重目的是1）确定可以通过盘旋波滑翔机询问器确定一个单个应答器的坐标的准确性，最多可以确定300 m的水深和2）测试一个可以容纳单个反应者的抗拖网结构的设计，该结构可以容纳单个反应者，该结构可以通过灾难的互动来自由，从而反映了通过人类的依据。优点和更广泛的影响审查标准。