Developing a new calibrated pressure sensor for the Ocean Observatories Initiative Cabled Array and other applications

海底压力的测量对于了解地球和海洋是有用的，因为它们对海底高度的变化以及上面的水和大气的重量很敏感。最好的压力传感器的漂移是不可预测的，因此它们的输出不能用于解析长期信号，如俯冲带地震之间的稳定应变积累和海洋质量的长期变化。漂移还使现有的压力传感器对缓慢滑动的地震和海洋涡流等短期信号不那么敏感。开发了一种利用仪器外壳内部压力作为参考来消除漂移的新方法，并在海底样机上进行了成功的测试。该项目将重新设计原型，使仪器更坚固，更好地校准，更紧凑，更低功耗。它将被连接到轴向海底山的海洋观测倡议电缆阵列上，轴向海底山是一座火山，自2015年爆发以来正在迅速膨胀。工程方面的努力将由一名女性工程师在一个女性代表不足的领域领导，该项目将培训一名研究生参加一个技术项目，他们将学习与工程师和科学家一起工作。为海洋观测倡议有线阵列提供服务和部署仪器的游轮包括大量本科生，其中一名学生将参与与该仪器相关的项目。a -0- a法是一种校正压力传感器消除漂移的新方法。周期性地，用一个阀门在短时间间隔内切换压力传感器，从测量海洋中的压力切换到测量仪器外壳内的压力。然后可以通过将压力读数与精确的气压计进行比较来确定漂移。a -0- a方法有可能以比目前方法经济得多的方式大大减少长期海底压力记录的漂移。在蒙特利湾900米深的MARS电缆观测站进行的首次非专有海底测试表明，A-0-A校准可以将压力传感器在1000米深的水中的漂移减少到每年1-2毫米。然而，需要改进设计以消除已知的误差来源，并且必须进行并排海底测试，以验证该技术与现有的漂移消除方法的对比。重新设计的仪器首次部署在轴向海山，将与Scripps海洋学研究所自校准压力记录仪（一种使用自重测试仪进行周期性校准的仪器）的绝对压力测量结果和通过重复闭环移动压力记录仪测量获得的相对压力测量结果进行比较，两者的不确定度均为1厘米。该电缆传感器可用于未来对卡斯卡迪亚俯冲带大逆冲断层的垂直大地测量研究，旨在了解断层锁定、蠕变和慢滑的模式。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Measurements of seafloor pressure are useful for understanding the earth and the ocean because they are sensitive to changes in the height of the seafloor and the weight of the overlying water and atmosphere. The best pressure sensors drift unpredictably so their output cannot be used to resolve long terms signals such as the steady buildup of strain between subduction zone earthquakes and long term changes in the mass of the oceans. Drift also makes existing pressure sensors less sensitive to shorter-term signals such as those from slow-slip earthquakes and ocean eddies. A new method has been developed to remove drift using the internal pressure inside the instrument housing as a reference and has been tested successfully with a seafloor prototype. This project will redesign the prototype so that the instrument is more robust, better calibrated, more compact and lower power. It will be attached to the Ocean Observatories Initiative Cabled Array on Axial Seamount, a volcano that is inflating rapidly following an eruption in 2015. The engineering effort will be led by a female engineer in a field where women are underrepresented and the project will train a graduate student in a technical project where they will learn to work with both engineers and scientists. The cruises that service and deploy instruments on the Ocean Observatories Initiative Cabled Array incorporate a large number of undergraduate students, and one will be engaged to conduct a project related to this instrument.The A-0-A method is a new approach to calibrating pressure sensors to remove drift. Periodically, a valve is used to switch the pressure sensor for a short interval from measuring the pressure in the ocean to measuring the pressure inside the instrument housing. The drift can then be determined by comparing the pressure readings to an accurate barometer. The A-0-A method has the potential to substantially reduce the drift of long-term seafloor pressure records in a much more economical way than current approaches. The first non-proprietary seafloor tests at 900 m in Monterey Bay on the MARS cabled observatory suggests that A-0-A calibrations may reduce pressure sensor drift to as little as 1-2 mm/year in 1000 m of water. However, design improvements are required to remove known sources of error and a side-by-side seafloor test is essential to verify the technique against established methods of drift removal. The first deployment of the redesigned instrument on Axial Seamount will allow comparisons with the absolute pressure measurements of the Scripps Institution of Oceanography Self-Calibrating Pressure Recorder (an instrument that uses a dead weight tester for periodic calibrations) and the relative pressure measurements obtained from repeat closed-loop mobile pressure recorder surveys, both of which have an uncertainty of ~1 cm of water. The cabled sensor can then be used for future vertical geodetic studies of the Cascadia subduction zone megathrust aimed at understanding patterns of fault locking, creep and slow slip.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.