The Representation of Ocean Circulation and Variability in Thermodynamic Coordinates
The Representation of Ocean Circulation and Variability in Thermodynamic Coordinates
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DOI：
10.1175/jpo-d-13-0213.1
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发表时间：
2014-07
影响因子：
3.5
通讯作者：
S. Groeskamp;J. Zika;T. McDougall;B. Sloyan;F. Laliberté
中科院分区：
文献类型：
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作者：
S. Groeskamp;J. Zika;T. McDougall;B. Sloyan;F. Laliberté
海洋环流在绝对盐度 SA 和保守温度 Q 坐标中进行分析。它被分为 1) 与 SA 和 Q 等值面法向方向上的地理位移相关的平流分量，以及 2) 与 SA–Q 值的局部变化相关的局部分量，无地理位移。在这种分解中，环流的平流成分和局部成分之和相当于SA和Q的物质导数。该总和与盐和热的源和汇直接相关。平流分量由平流温盐流函数 C advAQ 表示。去除趋势后，局部分量可以用局部温盐流函数C locAQ 表示。在这里，可以使用观测数据集中的 SA 和 Q 的月平均时间序列来诊断 C locAQ。此外，C advAQ 和 C locAQ 是根据耦合气候模型确定的。透温盐流函数 C diaAQ 是 C advAQ 和 C locAQ 之和，代表 SA-Q 坐标中的非发散透温盐环流。透温盐趋势由 SA 和 Q 的局部变化趋势产生，量化了 SA-Q 坐标中海洋体积随时间的重新分布。有人认为，透热盐流函数为海洋模型和基于观测的网格气候学的分析和比较提供了有力的工具。
The ocean’s circulation is analyzed in Absolute Salinity SA and Conservative Temperature Q coordinates. It is separated into 1) an advective component related to geographical displacements in the direction normal to SA and Q isosurfaces and 2) into a local component, related to local changes in SA–Q values, without a geographical displacement. In this decomposition, the sum of the advective and local components of the circulation is equivalent to the material derivative of SA and Q. The sum is directly related to sources and sinks of salt and heat. The advective component is represented by the advective thermohaline streamfunction C advAQ. After removing a trend, the local component can be represented by the local thermohaline streamfunction C locAQ. Here, C locAQ can be diagnosed using a monthly averaged time series of SA and Q from an observational dataset. In addition, C advAQ and C locAQ are determined from a coupled climate model. The diathermohaline streamfunction C diaAQ is the sum of C advAQ and C locAQ and represents the nondivergent diathermohaline circulation in SA–Q coordinates. The diathermohaline trend, resulting from the trend in the local changes of SA and Q, quantifies the redistribution of the ocean’s volume in SA–Q coordinates over time. It is argued that the diathermohaline streamfunction provides a powerful tool for the analysis of and comparison among ocean models and observation-based gridded climatologies.