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arXiv 1609.09616physics.ao-ph
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用局部识别方案研究Southern Ocean锋面变率的新观点

New Perspectives on Frontal Variability in the Southern Ocean Using a Local Identification Scheme

Christopher C. Chapman

摘要:

南大洋的锋面结构进行了调查,使用先进的锋面探测方法,小波/高阶统计增强(WHOSE)的方法,在\cite{Chapman2014}介绍。这种方法适用于21年的每日网格化的海面高度(SSH)的数据,以获得每日地图的前线的位置。通过形成“热图”的锋面发生频率,然后近似这些热图的叠加简单的功能,时间平均位置的前,以及衡量他们的能力,曲折,获得和相关的锋面位置发现以前的研究。锋面结构的空间和时间的变化,然后考虑。在整个南大洋,锋面的数量变化很大,在大的水深特征下游增加(“分裂”),在锋面受底层地形严格控制的区域减少(“合并”)。相反,锋面曲流相对稳定。与许多先前的研究相反,在1993-2014年期间,几乎没有发现锋面的南移,并且对SAM或ENSO相关的大气强迫只有弱敏感性。本研究和以前的研究使用等高线方法之间的差异的原因进行了调查,它表明,锋面结构的空间变异性是不依赖于下垫面的海面高度。有人认为,使用海面高度等值线来定义锋的研究结果必须小心解释。

英文摘要:

The frontal structure of the Southern Ocean is investigated using a sophisticated frontal detection methodology, the Wavelet/Higher Order Statistics Enhancement (WHOSE) method, introduced in \cite{Chapman2014}. This methodology is applied to 21 years of daily gridded sea-surface height (SSH) data to obtain daily maps of the locations of the fronts. By forming `heat-maps' of the frontal occurrence frequency and then approximating these heat-maps by a superposition of simple functions, the time-mean locations of the fronts, as well as a measure of their capacity to meander, are obtained and related to the frontal locations found by previous studies. The spatial and temporal variability of the frontal structure is then considered. The number of fronts is found to be highly variable throughout the Southern Ocean, increasing (`splitting') downstream of large bathymetric features and decreasing (`merging') in regions where the fronts are tightly controlled by the underlying topography. In contrast, frontal meandering remains relatively constant. Contrary to many previous studies, little no southward migration of the fronts over the 1993-2014 time period is found, and there is only weak sensitivity to atmospheric forcing related to SAM or ENSO. The reasons for the discrepancy between this study and previous studies using contour methods are investigated and it is shown that the spatial variability of the frontal structure is not tied to the underlying sea-surface height. It is argued that the results of studies using sea-surface height contours to define front must be interpreted with care.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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