The thermal component of oceanic eddy available potential energy (EPE) generation due to air‐sea interaction is proportional to the product of anomalous sea surface temperature (SST) and net air‐sea heat flux (SHF). In this study we assess EPE generation and its timescale and space‐scale dependence from observations and a high‐resolution coupled climate model. A dichotomy exists in the literature with respect to the sign of this term, that is, whether it is a source or a sink of EPE. We resolve this dichotomy by partitioning the SST and net heat flux into climatological mean, climatological seasonal cycle, and remaining transient contributions, thereby separating the mesoscale eddy variability from the forced seasonal cycle. In this decomposition the mesoscale air‐sea SST‐SHF feedbacks act as a 0.1 TW global sink of EPE. In regions of the ocean with a large seasonal cycle, for example, midlatitudes of the Northern Hemisphere, the EPE generation by the forced seasonal cycle exceeds the mesoscale variability sink, such that the global generation by seasonal plus eddy variability acts as a 0.8 TW source. EPE destruction is largest in the midlatitude western boundary currents due to mesoscale air‐sea interaction and in the tropical Pacific where SST variability is due mainly to the El Niño–Southern Oscillation. The EPE sink in western boundary currents is spatially aligned with SST gradients and offset to the poleward side of currents, while the mean and seasonal generation are aligned with the warm core of the current. By successively smoothing the data in space and time we find that half of the EPE sink is confined to timescales less than annual and length scales less than 2°, within the oceanic mesoscale band.

中文翻译：

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中尺度海气相互作用造成的可用势能的全球汇


由于海气相互作用而产生的海洋涡流可用势能（EPE）的热成分与异常海面温度（SST）和净海气热通量（SHF）的乘积成正比。在这项研究中，我们通过观测和高分辨率耦合气候模型评估了 EPE 的产生及其时间尺度和空间尺度的依赖性。文献中关于该术语的符号存在二分法，即它是 EPE 的源还是汇。我们通过将海温和净热通量划分为气候平均值、气候季节循环和剩余瞬态贡献来解决这种二分法，从而将中尺度涡流变化与强制季节循环分开。在此分解中，中尺度气海 SST-SHF 反馈充当 EPE 的 0.1 TW 全球汇。在季节周期较大的海洋区域，例如北半球中纬度地区，强制季节周期产生的 EPE 超过了中尺度变率汇，因此季节性加涡流变率产生的全球 EPE 相当于 0.8 TW 源。由于中尺度气海相互作用，EPE 破坏在中纬度西部边界流中最为严重，而在热带太平洋，海温变化主要由厄尔尼诺-南方涛动造成。西部边界洋流中的 EPE 汇在空间上与海温梯度一致，并偏移到洋流的极地一侧，而平均和季节性发电量与洋流的暖核心一致。通过对数据在空间和时间上的连续平滑，我们发现一半的EPE汇被限制在海洋中尺度带内小于年的时间尺度和小于2°的长度尺度内。