Temporal variability of internal waves and vertical mixing in the North Atlantic

北大西洋内波和垂直混合的时间变化

基本信息

批准号：
257192667
负责人：
Dr. Janna Köhler
金额：
--
依托单位：
Institut für Umweltphysik (IUP)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/257192667?language=en
关键词：
Temporal variability internal waves vertical

项目摘要

The general objective of this project is the investigation of temporal variability in internal wave energy and the intensity of vertical mixing in relation to the North Atlantic Current and its eddy field. Thereby 5-6 year long observations from moored current meters and temperature/conductivity recorders from three moorings along a section west of the Mid-Atlantic Ridge as well as shipboard LADCP/CTD measurements will be used. Specific scientific goals are:- produce time series of internal wave energy from moored observation of currents and stratification - investigate time scales of variability in relation to wind input, position of NAC and eddies- identify generating processes of the observed variability, e.g. tides, storms, seasonal cycle, eddies, NAC branches (local/remote forcing)- determine variability of mixing (temperature inversions, Thorpe scales, finescale parameterization) in dependence on changing background propertiesTo achieve the above objectives, internal wave potential and kinetic energy spectra will be calculated and studied for their relation to variable background properties e.g. wind forcing, tides, passing eddies, stratification and variability in the NAC branches as well as for their dependence on the local MAR topography. Mooring instrumentation since summer 2012 additionally permits the calculation of internal wave vertical modes and energy fluxes which will yield information about the magnitude and temporal variability of energy transported by internal waves in the North Atlantic. Combining calculated energy fluxes with ray tracing methods for internal waves generated at the MAR will also enable the estimation of the relative importance of the MAR topography for the generation of internal waves in the study area. From summer 2015 onward analyses will be further extended by the calculation of time series of Thorpe scales and dissipation rates from temperature-pressure measurements. Results will be supplemented by the estimation of diapycnal diffusivities obtained from shipboard LADCP/CTD data from five cruises using a finescale parameterization. This allows the further analysis of dominant sources of internal waves and quantitative estimates of vertical mixing rates as well as their temporal and spatial variability

该项目的总体目标是研究内波能量的时间变化以及与北大西洋洋流及其涡流场相关的垂直混合强度。因此，将使用沿大西洋中脊以西部分的三个系泊点的系泊海流计和温度/电导率记录仪进行的 5-6 年观测，以及船上 LADCP/CTD 测量。具体的科学目标是： - 从系泊的海流和分层观测中产生内波能的时间序列 - 研究与风输入、NAC 和涡流位置相关的变化的时间尺度 - 识别观测到的变化的生成过程，例如潮汐、风暴、季节循环、涡流、NAC分支（本地/远程强迫）-根据不断变化的背景特性确定混合的可变性（温度倒转、索普尺度、精细尺度参数化）以实现上述目标、内波势和动能谱将计算和研究它们与可变背景属性的关系，例如风力强迫、潮汐、经过的涡流、NAC 分支的分层和变化以及它们对当地 MAR 地形的依赖。自 2012 年夏季以来，系泊仪器还允许计算内波垂直模式和能量通量，这将产生有关北大西洋内波传输的能量的幅度和时间变化的信息。将计算的能量通量与 MAR 生成的内波的射线追踪方法相结合，还可以估计 MAR 地形对于研究区域内波生成的相对重要性。从 2015 年夏季开始，通过计算索普尺度的时间序列和温度-压力测量的耗散率，分析将得到进一步扩展。结果将通过使用精细参数化从五次巡航的船上 LADCP/CTD 数据获得的径扩散率估计进行补充。这样可以进一步分析内波的主要来源并定量估计垂直混合率及其时间和空间变化