This paper describes the development of New Zealand's Earth System Model (NZESM) and evaluates its performance against its parent model (United Kingdom Earth System Model, UKESM) and observations. The main difference between the two earth system models is an embedded high‐resolution (1/5°) nested region over the oceans around New Zealand in the NZESM. Due to this finer ocean model mesh, currents such as the East Australian Current, East Australian Current Extension, Tasman Front, and Tasman Leakage, and their volume and heat transports are better simulated in the NZESM. The improved oceanic transports have led to a reduction in upper ocean temperature and salinity biases over the nested region. In addition, net transports through the Tasman Sea of volume, heat and salt in the NZESM agree better with previously reported estimates. A consequence of the increased cross‐Tasman Sea transports in the NZESM is increased temperatures and salinity west of Australia and in the Southern Ocean reducing the meridional sea surface temperature gradient between the subtropics and sub‐Antarctic. This also leads to a weakening of the westerly winds between 60°S and 45°S over large parts of the Southern Ocean, which reduces the northward Ekman transport, reduces the formation of Antarctic Intermediate Water, and allows for a southward expansion of the Super‐Gyre in all ocean basins. Connecting an improved oceanic circulation around New Zealand to a basin‐wide Super‐Gyre response is an important step forward in our current understanding of how local scales can influence global scales in a fully coupled earth system model.

中文翻译：

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新西兰地球系统模型中的局部网格细化：塔斯曼海海洋环流的改善和超环流的影响

本文介绍了新西兰地球系统模型（NZESM）的发展，并根据其母模型（英国地球系统模型UKESM）和观测结果对其性能进行了评估。两种地球系统模型之间的主要区别在于NZESM中新西兰周围海洋上的嵌入式高分辨率（1/5°）嵌套区域。由于采用了更精细的海洋模型网格，因此在NZESM中可以更好地模拟东澳大利亚洋潮流，东澳大利亚洋扩展，塔斯曼前锋和塔斯曼泄漏等洋流及其体积和热传输。改善的海洋运输导致降低了较高的海洋温度和嵌套区域的盐度偏差。此外，通过NZESM的塔斯曼海的净运输量，热量和盐分与先前报道的估计更吻合。NZESM中塔斯曼海跨境运输增加的结果是澳大利亚西部和南大洋的温度和盐度升高，从而降低了亚热带和南极洲之间的子午海面温度梯度。这也导致南大洋大部分地区60°S至45°S之间的西风减弱，这减少了向北的埃克曼运移，减少了南极中间水的形成，并使超级大洋向南扩张。在所有海盆中都有涡流。在我们目前对局部尺度如何在完全耦合的地球系统模型中影响全球尺度的理解中，将新西兰周围不断改善的海洋环流与全盆地范围的超环流响应联系起来是重要的一步。