北极和南极海冰范围变化的年和半年分量
On the annual and semi-annual components of variations in extent of Arctic and Antarctic sea-ice
摘要：
对北半球（NHSI）和南半球（SHSI）海冰范围时间序列进行奇异谱分析（SSA）。用刘维-欧拉系统的拉普拉斯公式分析了这些部件。正如已经在以前的工作中所示，在时间序列中观察到的趋势是准线性的，NHSI减少，SHSI增加。南极年变化的幅度是北极的两倍，它们是反相的，调制的。半年分量是正交的。NHSI和SHSI在1年、1/2年和1/3年的前3个分量占信号方差的95%以上。我们补充以前的分析极点位置（PM = m1，m2）和一天的长度（lod）的变化。与海冰的SSA一样，lod的SSA也由前3个分量主导，而PM的SSA仅包含1年和Chandler分量。NHSI的1年分量与lod同相，与m1反相。相反的情况适用于SHSI的1年部分。我们注意到半年分量出现在lod中而不是m1中。NHSI和SHSI的年度和半年分量比1978年以来观测到的趋势大得多，这使我们能够测试一阶地球物理或天文强迫是否不应该优先于通常建议作为趋势强迫因子的机制。最大强迫分量的调制的缺乏表明一种替代机制。在拉普拉斯的范式中，月球、太阳和行星所施加的力矩作为许多地球物理现象的强迫源起着主导作用。这些力导致地球自转轴倾斜度的变化，使地球质量运动，导致热耗散。旋转轴倾角的变化导致了海冰融化和再冻结的大的年度分量。
英文摘要：
The time series of northern hemisphere (NHSI) and southern hemisphere (SHSI) sea-ice extent are submitted to singular spectral analysis (SSA). The components are analyzed with Laplace's formulation of the Liouville-Euler system. As already shown in a previous work, the trends observed in the time series are quasi linear, decreasing for NHSI and increasing for SHSI. The amplitude of annual variations in the Antarctic is double that in the Arctic, they are in phase opposition, modulated. The semi-annual components are in quadrature. The first 3 components of both NHSI and SHSI at 1, 1/2 and 1/3 yr account for more than 95% of the signal variance. We complement previous analyses of variations in pole position (PM = m1, m2) and length of day (lod). Whereas SSA of lod is dominated by the same first 3 components as sea-ice, SSA of PM contains only the 1 yr and the Chandler components. The 1 yr component of NHSI is in phase with that of lod and in phase opposition with m1. The reverse holds for the 1 yr component of SHSI. We note that the semi-annual component appears in lod not in m1. The annual and semi-annual components of NHSI and SHSI are much larger than the trends observed since 1978, that leads us to test whether a first order geophysical or astronomical forcing should not be preferred to the mechanisms generally suggested as a forcing factor of the trends. The lack of modulation of the largest forced component suggests an alternate mechanism. In Laplace's paradigm, the torques exerted by the Moon, Sun and planets play the leading role as the source of forcing of many geophysical phenomena. These forces lead to changes in the inclination of the Earth's rotation axis, setting Earth masses in motion and resulting in thermal dissipation. It is variations in inclination of the rotation axis that lead to the large annual components of melting and re-freezing of sea-ice.
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