论文标题
一般海洋循环的全球能源光谱
Global Energy Spectrum of the General Oceanic Circulation
论文作者
论文摘要
Since the advent of satellite altimetry, our perception of the oceanic circulation has brought into focus the pervasiveness of mesoscale eddies that have typical scales of tens to hundreds of kilometers [5], are the ocean's analogue of weather systems, and are often thought of as the peak of the ocean's kinetic energy (KE) wavenumber spectrum [7, 19, 23].然而，我们对海洋空间尺度的理解主要来自小型代表区域的傅立叶分析（例如[16、14、4]），通常大小几百公里，无法捕获行星尺度下的巨大动态范围。在这里，我们使用粗粒的方法来分析比以前可能大得多的量表，从卫星数据和高分辨率重新分析数据中介绍了海洋循环的第一个真正的全球波数谱。长度尺度上三个数量级超过三个数量级的光谱揭示了南极极性电流（ACC）作为全球热带海洋的光谱峰，约为$ \ 10 \ times 10^3〜 $ km。我们还发现了以前未观察到的幂律缩放，大于$ 10^3〜 $ km。较小的光谱峰值在$ \ 300〜 $ km处存在与中尺相关的峰值，由于它们在波数空间中的扩展较大，因此在全球范围内已解决的表面KE的$ 50 \％$ $ 50 \％。长度尺度的大尺度是大的（最多（10^3 \）〜km）的两倍，其特征性滞后时间为\（\ of40〜 \）天的季节性周期，因此在春季后期的$ 100〜 $ km的$ 100〜 $ km中，KE在$ 10^3〜 $ km的峰值处于夏季，夏季夏季夏季均为$ 10^3〜 $ km。这里介绍的频谱为我们提供了一个新的窗口，以了解地球气候系统中的多尺度一般海洋循环，包括最大的行星尺度。
Since the advent of satellite altimetry, our perception of the oceanic circulation has brought into focus the pervasiveness of mesoscale eddies that have typical scales of tens to hundreds of kilometers [5], are the ocean's analogue of weather systems, and are often thought of as the peak of the ocean's kinetic energy (KE) wavenumber spectrum [7, 19, 23]. Yet, our understanding of the ocean's spatial scales has been derived mostly from Fourier analysis in small representative regions (e.g. [16, 14, 4]), typically a few hundred kilometers in size, that cannot capture the vast dynamic range at planetary scales. Here, we present the first truly global wavenumber spectrum of the oceanic circulation from satellite data and high-resolution re-analysis data, using a coarse-graining method to analyze scales much larger than what had been possible before. Spectra spanning over three orders of magnitude in length-scale reveal the Antarctic Circumpolar Current (ACC) as the spectral peak of the global extra-tropical ocean, at $\approx 10 \times 10^3~$km. We also find a previously unobserved power-law scaling over scales larger than $10^3~$km. A smaller spectral peak exists at $\approx 300~$km associated with the mesoscales, which, due to their wider spread in wavenumber space, account for more than $50\%$ of the resolved surface KE globally. Length-scales that are twice as large (up to \(10^3\)~km) exhibit a characteristic lag time of \(\approx40~\)days in their seasonal cycle, such that in both hemispheres KE at $100~$km peaks in late spring while KE at $10^3~$km peaks in late summer. The spectrum presented here affords us a new window for understanding the multiscale general oceanic circulation within Earth's climate system, including the largest planetary scales.
