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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

该项目的总目标是调查内波能量的时间变化和与北大西洋海流及其涡流场有关的垂直混合强度。因此，将使用沿大西洋中脊以西一段沿着三个系泊处的系泊海流计和温度/电导率记录仪以及船上LADCP/CTD测量的5-6年观测结果。具体的科学目标是：- 通过对海流和分层的系泊观测产生内波能量的时间序列-研究与风输入、NAC和涡流位置相关的变化的时间尺度-确定观测到的变化的生成过程，例如潮汐、风暴、季节周期、涡流、NAC分支（本地/远程强迫）-确定混合的可变性（温度逆温、索普尺度、细尺度参数化）对变化的背景特性的依赖为实现上述目标，将计算内波势和动能谱，并研究它们与变化的背景特性（如风强迫、潮汐、通过的涡旋）的关系，NAC分支的分层和变异性以及它们对当地MAR地形的依赖性。自2012年夏季以来的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能量的大小和时间变化的信息。结合计算的能量通量与射线追踪方法产生的内波在MAR也将能够估计的相对重要性的MAR地形生成内波在研究区域。从2015年夏季开始，将通过计算温度-压力测量的索普尺度和耗散率的时间序列来进一步扩展分析。结果将得到补充的估计diapycnal扩散系数从船上的LADCP/CTD数据从五个邮轮使用细尺度参数化。这使得进一步分析内波的主要来源和定量估计垂直混合率及其时空变化