WOCE AIMS: Analysis of Tracer Ages and Estimate of Isopycnal Mixing

0136973精细本项目的目标是估计单个示踪剂年龄的不确定度，并将这些不确定度大小的差异与已知的环流现象联系起来。重点是温跃层和中间水团，利用最近获得的世界海洋环流实验(WOCE)的氯氟碳和氚/氦-3数据。示踪年龄是海洋将大气成分输送到内陆的能力的衡量标准。将计算副热带环流区域的等周期混合率，在这些区域中，等周期混合可以显著改变示踪年龄。示踪年龄的误差是由分析、源函数和其他因素引起的。这里将对示踪剂年龄误差和分布误差进行区分。与海洋过程的影响相比，误差对示踪剂年龄分布的影响较小。根据混合的程度和途径，示踪剂可以在给定的水团中显示出广泛的年龄分布。因此，混合影响了解释示踪剂年龄的能力，即水团与大气接触以来所经过的时间。混合历史将通过用公认的理论框架分析示踪剂年龄的分布来评估。副热带气旋各分区的等周期混合率和Peclet数将被计算出来。这些值将与示踪剂年龄分布和非线性混合项进行比较。这项工作将利用假定为静止环流的北大西洋高分辨率数值模式进行扩展。这将使得能够分析模拟的氟氯化碳和理想年龄、它们的分布、与观测值的比较以及对模型中的通风和混合的评估。拟议的多重示踪剂方法的结果将有助于量化海洋吸收大气气体的速度，例如二氧化碳。

0136973 FineThe goal of this project to estimate the uncertainties for individual tracer ages, and to associate differences in the magnitude of these uncertainties with known circulation phenomena. The focus is on thermocline and intermediate water masses, using World Ocean Circulation Experiment (WOCE) chlorofluorocarbon and tritium/helium-3 data that have recently become available. Tracer ages are a measure of the ocean's ability to transport atmospheric constituents into the interior. Isopycnal mixing rates will be calculated for regions of the subtropical gyres where isopycnal mixing can significantly alter tracer ages. Errors in tracer ages arise from analytical, source function, and other factors. Here a differentiation will be made between errors in tracer ages and distributions. The effect of errors on tracer age distributions is small compared with effects of oceanic processes. Depending on the extent and pathways of mixing, a tracer can exhibit a broad distribution of ages within a given water mass. Mixing, therefore, compromises the ability to interpret tracer ages; i.e., the elapsed time since a water parcel was in contact with the atmosphere. Mixing histories will be assessed by analyzing distributions of tracer ages with an accepted theoretical framework. Isopycnal mixing rates and Peclet numbers will be calculated for sub-regions of the subtropical gyres. These values will be compared to tracer age distributions and non-linear mixing terms. The work will be extended using a high resolution numerical model of the North Atlantic with an assumed stationary circulation. This will permit analysis of simulated CFC and ideal ages, their distributions, comparison with observations, and assessment of ventilation and mixing in the model. Results from the proposed multiple tracer approach will contribute toward quantifying the rate at which the ocean takes up atmospheric gases, for example, CO2.