地球核心表面的行星环流、随时间变化的涡旋、扭转波和赤道喷流
Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth's core surface
摘要：
我们报告了1940-2010年随时间变化的准地转核心流的计算。递归反演的合奏的解决方案，我们评估的主要来源的不确定性，即未解决的核心表面运动和磁场之间的相互作用所产生的模型误差。这些不确定性的时间相关性占。的协方差矩阵的流量系数也得到递归从一个合奏的解决方案的分散。核心表面的流动地图显示，在行星尺度的环流上，中纬度地区存在与时间相关的大尺度涡旋，赤道带存在强烈的方位角喷流。在我们所能分辨的所有空间尺度上，流动的静止部分占主导地位。我们检索扭转波，解释在4至9.5年的周期的日长变化。这些波可能是由磁场和流体外核内的近十年非纬向运动之间的非线性相互作用触发的。1995年至2010年期间，纬向和更活跃的非纬向年际运动在赤道附近（低于10度纬度）特别强烈。我们向下修正的行星尺度环流的十年波动的幅度，发现电磁核幔耦合不是角动量交换的主要机制，在十年尺度上，如果地幔电导是3 - 10 - 8 S或更低。
英文摘要：
We report a calculation of time-dependent quasi-geostrophic core flows for 1940-2010. Inverting recursively for an ensemble of solutions, we evaluate the main source of uncertainties, namely the model errors arising from interactions between unresolved core surface motions and magnetic fields. Temporal correlations of these uncertainties are accounted for. The covariance matrix for the flow coefficients is also obtained recursively from the dispersion of an ensemble of solutions. Maps of the flow at the core surface show, upon a planetary-scale gyre, time-dependent large-scale eddies at mid-latitudes and vigorous azimuthal jets in the equatorial belt. The stationary part of the flow predominates on all the spatial scales that we can resolve. We retrieve torsional waves that explain the length-of-day changes at 4 to 9.5 years periods. These waves may be triggered by the nonlinear interaction between the magnetic field and sub-decadal non-zonal motions within the fluid outer core. Both the zonal and the more energetic non-zonal interannual motions were particularly intense close to the equator (below 10 degrees latitude) between 1995 and 2010. We revise down the amplitude of the decade fluctuations of the planetary scale circulation and find that electromagnetic core-mantle coupling is not the main mechanism for angular momentum exchanges on decadal time scales if mantle conductance is 3 10 8 S or lower.
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