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

摘要-0452744-0452265利用低频(10-150赫兹)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，对海洋细小结构进行了一次联合水文/地震成像调查，获得了110个XBT和12个XCTD的温度和盐度数据，作为挪威海先前预定的地震反射研究的一个低成本补充。初步结果表明，反射法(1)对低至0.03摄氏度的细尺度温差很敏感；(2)能从M2内潮汐成像精细结构，并绘制M2内潮汐发潮地点图；(3)能非常详细地绘制水团边界图；(4)能产生定量内波谱，重现预期的Garrett-Munk谱及其偏差；(5)能在临界大陆斜坡上成像与内波一致的细结构。这项建议将重点分析数据，针对以下问题：(1)如何最好地从精细结构的声波图像中提取关于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，是否有随深度、距大陆坡度和海底地形的系统性？(3)高波数内波能量在关键陆坡附近是否增强？(4)M2内潮是在挪威大陆坡的哪里产生的，坡度和潮汐周期是否具有系统性？(5)成像反射体与地转速度场有何关系？(6)各剖面所显示的深水块体边界形状如何？这项工作是确定低频声波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.