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Submarine Estimates of Arctic Turbulence Spectra (SEATS)

北极湍流频谱的潜艇估计 (SEATS)

基本信息

批准号：
NE/I028408/1
负责人：
Adrian Martin
金额：
$ 27.13万
依托单位：
NATIONAL OCEANOGRAPHY CENTRE
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FI028408%2F1
关键词：
Submarine Estimates Arctic Turbulence Spectra

项目摘要

The arctic ocean and it's peripheral seas comprise a seasonally variable mix of ice covered and ice-free open ocean and shelf waters that are considered to be one of the most sensitive regions to global change processes. Current estimated rates of multi-annual sea-ice loss appear to be exceeding model predictions. Despite the insulation from direct atmospheric forcing, mesoscale baroclinically unstable eddies (the oceanic's internal 'storm scale', 10-100 km) have been clearly observed through repeated salinity and temperature against depth profiles deployed through ice holes and more recently by the deployment of ice-tethered profiling instruments. Measurements of a turbulent well mixed boundary layer under sea-ice have been examined, establishing a mixed layer thickness closely coincident with an ice speed related frictional drag. For the same reason that different processes lead to the establishment of a turbulent mixed layer under ice compared to open waters, we expect that different mechanisms will lead to mixed layer re-stratification and therefore that the sub-mesoscale (1-10's km) interaction with mesoscale eddies and frontal boundaries will vary between ice-free and ice-covered regions. The aim of this study is an improved understanding of the characteristics of mixed layer variability in marginal or seasonally variable ice-covered regions, through the analysis of a large pre-existing data resource.Royal Navy (RN) submarines have collected temperature and salinity data in the Arctic, and elsewhere for a long time. For over 15 years RN submarines have been equipped with a sensor suite that also includes a number of biogeochemical instruments particularly for pigments such as chlorophyll(a) and 'yellow substance'. These data are normally highly classified and unavailable for research purposes outside and even largely within the MOD itself. This is because traditional research requirements include acquisition time/date and position. However, only vessel velocity, elapsed time (instrument sampling interval) and depth, within well known published ranges, are required to accompany the data-streams for us to examine the spatial cross correlation coefficients in the physical and biological parameters. This is a mechanism for looking at data collected spatially and temporally in terms of the time and space scales of the inherent variability contained within it. Specifically, discussions with our MOD collaborators indicate that significant amounts of data will be available both in the mixed layer and deeper. The wavenumber spectrum is simply proportional to the Fourier transform of these cross-correlation coefficients, and quantifies the contribution to variability from features at a range of length scales, including eddies and filaments. For general underway vessel velocities, the 'speed' of the observer is such that the time taken to traverse a structure is very much less than the time taken for its evolution for all but the smallest structures. The disturbance scale of the vessel O(100 m) will limit our study to sub-mesoscale filaments and above (~0.2-100 km). A key issue we can address is how closely related the spectra of other properties are to the physical spectra.

北冰洋及其周边海域由冰覆盖和无冰的开阔海洋和陆架水域组成，它们被认为是对全球变化过程最敏感的地区之一。目前估计的多年海冰消失率似乎超过了模型的预测。尽管不受直接大气强迫的影响，但通过对通过冰洞部署的深度剖面重复盐度和温度，以及最近通过部署冰系带剖面仪，可以清楚地观察到中尺度斜压不稳定涡旋(大洋内部的“风暴尺度”，10-100公里)。对海冰下湍流井混合边界层的测量进行了检验，确定了混合层厚度与冰速相关的摩擦阻力密切一致。由于与开放水域相比，不同的过程导致冰下湍流混合层的建立，我们预计不同的机制将导致混合层再层化，因此，次中尺度(1-10‘S公里)与中尺度涡旋和锋面边界的相互作用在无冰和有冰地区将有所不同。这项研究的目的是通过对大量现有数据资源的分析，更好地了解边缘或季节性变化的冰盖地区混合层变率的特征。皇家海军(RN)潜艇长期以来一直在北极和其他地方收集温度和盐度数据。15年来，RN潜艇已经装备了一套传感器，其中还包括一些生物地球化学仪器，特别是对叶绿素(A)和黄色物质等色素的检测。这些数据通常是高度机密的，不能用于国防部以外的研究目的，甚至主要是在国防部内部。这是因为传统的研究要求包括获取时间/日期和位置。然而，只需要在众所周知的公布范围内的血管速度、经过时间(仪器采样间隔)和深度来伴随数据流，我们就可以检查物理和生物参数中的空间互相关系数。这是一种根据数据所包含的内在变异性的时间和空间尺度来查看空间和时间上收集的数据的机制。具体地说，与我们的国防部合作者的讨论表明，在混合层和更深的层中都将有大量数据可用。波数谱与这些互相关系数的傅里叶变换成正比，并量化了包括涡流和细丝在内的一系列长度尺度上的特征对可变性的贡献。对于一般在航船的速度，观测者的速度是这样的，即穿过一个结构所花费的时间远远小于除了最小的结构之外的所有结构的演化所花费的时间。O(100m)船的扰动尺度将使我们的研究局限于亚中尺度细丝及以上(~0.2-100公里)。我们可以解决的一个关键问题是，其他性质的光谱与物理光谱的关系有多密切。