Climate‐driven polar motion
Climate‐driven polar motion
复制标题
DOI：
10.1029/1999jb900016
复制
发表时间：
1999-06
影响因子：
--
通讯作者：
M. Celaya;J. Wahr;F. Bryan
中科院分区：
文献类型：
--
作者：
M. Celaya;J. Wahr;F. Bryan
耦合气候系统模式的输出提供了一个综合的气候记录，其时间和空间覆盖范围是观测资料无法获得的，从而可以在数月到数十年的时间尺度上评估极地运动的气候激励。对大地测量推断的钱德勒激励功率的分析表明，自1900年以来，它的波动幅度高达90%，并且具有代表平稳高斯过程的特征。我们的模型预测的钱德勒摆动的气候激发也显示出与观测到的相比较的可变功率。洋流和海底压力变化共同作用就能驱动这14个月的摆动。气压和风的共同作用所产生的激振也是如此。海洋和大气的贡献之所以如此之大，是因为海底压力与海流、大气压力与风之间存在着相对高度的建设性干扰。相比之下，由陆地上的水再分配引起的刺激似乎在很大程度上微不足道。毫不奇怪，全面的气候影响比海洋或大气单独的影响更能驱动这种摆动。我们对观测到的年激励的匹配也得到了改善，比以前用历史气候数据做出的估计提高了约17%。解释30年马科维茨波动的努力没有那么成功。即便如此，在从几个月到几十年不等的周期内，一个耦合气候系统的模式所产生的激励与大地测量观测到的振幅非常接近。
The output of a coupled climate system model provides a synthetic climate record with temporal and spatial coverage not attainable with observational data, allowing evaluation of climatic excitation of polar motion on timescales of months to decades. Analysis of the geodetically inferred Chandler excitation power shows that it has fluctuated by up to 90% since 1900 and that it has characteristics representative of a stationary Gaussian process. Our model-predicted climate excitation of the Chandler wobble also exhibits variable power comparable to the observed. Ocean currents and bottom pressure shifts acting together can alone drive the 14-month wobble. The same is true of the excitation generated by the combined effects of barometric pressure and winds. The oceanic and atmospheric contributions are this large because of a relatively high degree of constructive interference between seafloor pressure and currents and between atmospheric pressure and winds. In contrast, excitation by the redistribution of water on land appears largely insignificant. Not surprisingly, the full climate effect is even more capable of driving the wobble than the effects of the oceans or atmosphere alone are. Our match to the observed annual excitation is also improved, by about 17%, over previous estimates made with historical climate data. Efforts to explain the 30-year Markowitz wobble meet with less success. Even so, at periods ranging from months to decades, excitation generated by a model of a coupled climate system makes a close approximation to the amplitude of what is geodetically observed.