The oceanic contribution to the Earth's seasonal angular momentum budget
The oceanic contribution to the Earth's seasonal angular momentum budget
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DOI：
10.1029/93gl03186
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发表时间：
1993-12
影响因子：
5.2
通讯作者：
J. Dickey;S. Marcus;C. M. Johns;R. Hide;S. Thompson
中科院分区：
文献类型：
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作者：
J. Dickey;S. Marcus;C. M. Johns;R. Hide;S. Thompson
地球自转速度的季节性变化表现为日长（LOD）的波动，幅度约为1000微秒（µs）。我们从以前的工作中知道，这些变化中至少有95%可以用大气和固体地球之间交换的角动量来解释。在这里，我们研究南极绕极流（ACC）和全球海洋对地球季节性角动量预算的各自贡献，使用德雷克海峡的现场数据和海洋区域模型的结果，（FRAM）和Maier-Reimer等人[1993]的全球海洋模式，由Brosche等人[1994]分析。1990年]。ACC的估计年贡献（2-4 µs）远小于海洋模式或现有LOD-AAM残差的总变化（均为15-20 µs）。在两个海洋模式中，估计的半年ACC贡献（3-8 µs）被更北的逆流所抵消，这两个海洋模式在行星角动量方面表现出更大的半年变化。因此，要进一步完善地球的季节性角动量收支，除了ACC的贡献外，还需要全球海洋的全部贡献（行星加相对贡献）。
Seasonal variations in the speed of the Earth's rotation manifest themselves as fluctuations in the length of the day (LOD) with an amplitude of about 1000 microseconds (µs). We know from previous work that at least 95% of these variations can be accounted for in terms of angular momentum exchanged between the atmosphere and the solid Earth. Here we examine the respective contributions of the Antarctic Circumpolar Current (ACC) and the global oceans to the Earth's seasonal angular momentum budget, using in situ data from the Drake Passage and results from both the oceanic regional model (Fine Resolution Antarctic Model—FRAM) of Webb et al. [1991] and the global oceanic model of Maier-Reimer et al. [1993] as analyzed by Brosche et al. [1990]. The estimated annual contribution of the ACC (2–4 µs) is much smaller than the total variation in the oceanic models or the existing LOD-AAM residual (both ∼15–20 µs). The estimated semi-annual ACC contribution (3–8 µs) is offset by counter-currents further north in both oceanic models, which exhibit larger semi-annual variations in planetary angular momentum. Further refinements in the Earth's seasonal angular momentum budget, therefore, will require the full (planetary plus relative) contribution of the global oceans in addition to that of the ACC.