Voyage to the bottom of the Puerto Rico Trench: Tales from a free fall current meter

2011 IEEE/OES 10th Current, Waves and Turbulence Measurements (CWTM) Pub Date : 2011-03-20 DOI:10.1109/CWTM.2011.5759538

W. Schmidt, E. Siegel

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Abstract

Near-bottom (∼2 m) current velocities in the Puerto Rico Trench (∼8350 m depth) were measured at 1 Hz for 75 min by a Nortek Deep Water Aquadopp acoustic-Doppler current meter at 19.75° N, 66.40° W, via untethered free descent/ascent vehicle. The April 2008 deployment also recorded 3-axis velocity, temperature, pressure, and instrument heading, pitch, roll, and signal-strength during the 153 min free descent, and while on bottom. Signal strength was above the noise floor for the entire data set, and SNR and velocity standard deviation were within known acceptable bounds above 7000 m. Instrument heading showed a continuous anticlockwise rotation during descent. Doppler vertical velocity during descent is compared to the pressure time derivative. Integration of horizontal velocity during descent suggests a lateral displacement of less than 30 m over the 8.35 km free-fall. Measurements made at impact indicate full functionality of the instrument at depth. Maximum horizontal velocities while on-bottom varied between 1 cm/s and 5 cm/s and were directed roughly along trench axis westward.

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航行到波多黎各海沟底部:从一个自由落体电流计的故事

在波多黎各海沟(~ 8350米深)，使用Nortek Deep Water Aquadopp声学多普勒流速仪在19.75°N, 66.40°W，以1 Hz频率测量75分钟的近底部(~ 2米)流速，通过无系绳的自由下降/上升装置。2008年4月的部署还记录了153分钟自由下降期间的3轴速度、温度、压力、仪表航向、俯仰、滚转和信号强度。整个数据集的信号强度都在噪声底之上，信噪比和速度标准差在7000 m以上的已知可接受范围内。仪器航向在下降过程中显示出连续的逆时针旋转。下降过程中的多普勒垂直速度与压力时间导数进行了比较。下降过程中的水平速度积分表明，在8.35公里的自由落体过程中，横向位移小于30米。在撞击处进行的测量表明仪器在深度处功能齐全。海底的最大水平速度在1 ~ 5 cm/s之间变化，大致沿海沟轴线向西方向。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2011 IEEE/OES 10th Current, Waves and Turbulence Measurements (CWTM)

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