Collaborative Research: Quantitative Investigation of Finestructure and Internal Waves in the Norwegian Sea from Simultaneous Temperature and Acoustic Reflectance Measurements

利用低频（10-150 Hz）地震反射剖面法可以对海洋精细结构进行非常详细的成像。2003年9月，进行了海洋精细结构水文/地震成像联合调查，获得了110 XBT.s和12 XCTD.s的温度和盐度数据，作为对先前计划在挪威海进行的地震反射研究的低成本附带。 初步结果表明，反射法（1）对小至0.03 ℃的精细尺度温度对比敏感;（2）可以从M2内潮中成像精细结构，并绘制M2内潮生成的位置;（3）可以绘制非常详细的水团边界;（4）可以产生定量的内波谱，再现预期的Garrett-Munk谱及其偏差;（5）可以在临界陆坡上成像与内波相一致的精细结构破裂。 本研究的重点是对数据的分析，主要针对以下几个问题：（1）如何从精细结构的声波图像中最好地提取内波位移谱和垂直相干性的定量信息？(2)挪威海温跃层内波场的特征是什么？是否存在与深度、距大陆坡距离和海底地形的系统性？ (3)高波数内波能量在临界大陆坡附近是否增强？ (4)挪威大陆坡的M2内潮产生于何处，是否存在坡度和潮汐周期的系统性？ (5)成像反射体与地转速度场的关系是什么？(6)在不同的剖面图中，深水区的边界是什么形状？ 这项工作是确定低频声学成像研究海洋结构和动力学的能力和局限性的合乎逻辑的下一步。

ABSTRACTOCE-0452744-0452265Oceanic finestructure can be imaged in great detail using low-frequency (10-150 Hz) seismic reflection profiling. In September 2003, a joint hydrographic/seismic imaging survey of oceanic finestructure was conducted, acquiring temperature and salinity data on 110 XBT.s and 12 XCTD.s as a low-cost piggyback to a previously scheduled seismic reflection study in the Norwegian Sea. Initial results showed that the reflection method (1) is sensitive to fine-scale temperature contrasts as small as 0.03 C; (2) can image finestructure from M2 internal tides and map the sites of M2 internal tide generation; (3) can map water-mass boundaries in great detail; (4) can produce quantitative internal wave spectra that reproduce the expected Garrett-Munk spectrum and deviations from it; and (5) can image disruptions in finestructure consistent with internal wave on critical continental slopes. This proposal will focus on analysis of the data, targeting the following questions: (1) How can we best extract quantitative information on internal wave displacement spectra and vertical coherence from acoustic images of finestructure? (2) What are the characteristics of the internal wave field in the thermocline of Norwegian Sea, and are there systematics with depth, distance from continental slope, and bottom topography? (3) Is high-wavenumber internal wave energy enhanced at sites near critical continental slopes? (4) Where are M2 internal tides generated on the Norwegian continental slope, and are there systematics with slope angle and tidal cycle? (5) What is the relationship of imaged reflectors to the geostrophic velocity field? (6) What is the shape of the deep water mass boundaries revealed in the various sections? This work is a logical next step in determining the capabilities and limitations of low-frequency acoustic imaging to study ocean structures and dynamics.