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

海底压力的测量有助于了解地球和海洋，因为它们对海底高度以及上覆水和大气的重量的变化很敏感。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，例如俯冲带地震和海洋质量长期变化之间不断积累的应变。漂移还会降低现有压力传感器对较短期信号的敏感度，例如来自慢滑地震和海洋漩涡的信号。开发了一种以仪器壳体内部压力为基准消除漂移的新方法，并已在海底样机上进行了成功的测试。这个项目将重新设计原型，使仪器更坚固，校准更好，更紧凑和更低的功率。它将附属于海洋天文台倡议轴海山上的电缆阵列，这是一座在2015年喷发后迅速膨胀的火山。工程项目将由一名女性代表不足的领域的一名女性工程师领导，该项目将培训一名技术项目的研究生，在这个项目中，他们将学习与工程师和科学家合作。在海洋观测站有线阵列上服务和部署仪器的邮轮包括了大量的本科生，其中一人将从事与该仪器相关的项目。A-0-A方法是校准压力传感器以消除漂移的一种新方法。定期使用阀门在短时间内将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方法有可能以一种比目前的方法经济得多的方式大幅减少长期海底压力记录的漂移。首次在火星电缆天文台蒙特利湾900米处进行的非专有海底测试表明，A-0-A校准可能会将压力传感器在1000米水中的漂移减少到1-2毫米/年。然而，需要改进设计以消除已知的误差源，并且并排海底测试对于对照既定的漂移消除方法来验证该技术至关重要。在轴海山上首次部署重新设计的仪器将能够与斯克里普斯海洋学研究所的绝对压力测量结果(使用自重测试仪进行定期校准的仪器)和通过重复进行闭路移动压力记录仪调查获得的相对压力测量结果进行比较，这两种测量结果的不确定度均为约1厘米。有线传感器随后可用于卡斯卡迪亚俯冲带巨型逆冲的未来垂直大地测量研究，旨在了解断层锁定、蠕动和慢滑的模式。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.