The meridional variability of the Subtropical Front (STF) and the drivers of variability on interannual time scales in the New Zealand region are analyzed using a multi‐decadal eddy‐resolving ocean hindcast model, in comparison with Argo data. The STF marks the water mass boundary between subtropical waters and subantarctic waters, and is defined as the southern‐most location of the 11°C isotherm and 34.8 psu isohaline between 100 and 500 m. The STF shifts up to 650 km (6°) meridionally on seasonal timescales. In addition to seasonal variability, shifts of around 200 km (2°) occur on interannual time scales. These shifts are connected to regional wind stress curl anomalies in the eastern Tasman Sea and east of New Zealand, which trigger Ekman convergence/divergence and Rossby waves and result in meridional transport of heat and salt into/out of the Tasman Sea. The net transports across the northern boundary of the Tasman Sea show the largest sensitivity to these wind stress curl anomalies. During periods of positive wind stress curl anomalies and Ekman convergence, the heat and salt content increases shifting the position of the STF southward. The opposite tendency occurs during periods of negative wind stress curl anomalies. The migration of the STF does not appear to be directly linked to regional climate oscillations.

中文翻译：

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新西兰地区亚热带锋面的季节和年际变化

与Argo数据相比，使用多年代解析涡旋海洋后倾模型分析了新西兰地区副热带锋（STF）的子午经度变化和年际时标变化的动因。STF标记了亚热带水域与亚南极水域之间的水质边界，并被定义为11°C等温线和34.8 psu等盐度在100至500 m之间的最南端。在季节性时标上，STF子午线最高可移动650 km（6°）。除了季节性变化之外，在每年的时间尺度上还会发生约200 km（2°）的变化。这些变化与塔斯曼海东部和新西兰东部的区域性风应力卷曲异常有关，会触发埃克曼会聚/发散和Rossby波，并导致热量和盐的经向传输到塔斯曼海。塔斯曼海北部边界的净运输对这些风应力卷曲异常表现出最大的敏感性。在正风应力卷曲异常和Ekman收敛期间，热量和盐含量会增加，STF的位置会向南移动。在负风应力卷曲异常期间会出现相反的趋势。STF的迁移似乎与区域气候波动没有直接关系。热量和盐分增加，STF的位置向南移动。在负的风应力卷曲异常期间会出现相反的趋势。STF的迁移似乎与区域气候波动没有直接关系。热量和盐分增加，STF的位置向南移动。在负风应力卷曲异常期间会出现相反的趋势。STF的迁移似乎与区域气候波动没有直接关系。