Atmospheric, hydrological, and ocean current contributions to Earth's annual wobble and length‐of‐day signals based on output from a climate model
Atmospheric, hydrological, and ocean current contributions to Earth's annual wobble and length‐of‐day signals based on output from a climate model
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DOI：
10.1029/2001jb000457
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发表时间：
2003
影响因子：
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通讯作者：
M. Zhong;I. Naito;A. Kitoh
中科院分区：
文献类型：
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作者：
M. Zhong;I. Naito;A. Kitoh
[1]大气，水文和洋流的贡献，每年的摆动和日长变化的调查，根据10年的月数值模拟的海洋-大气环流模式（COAGCM）。还使用了从“SPACE 97”数据中观测到的摆动推断出的大地激发时间序列，以及作为参考，日本气象厅（JMA）1988-1997年期间业务目标分析数据的大气角动量（AAM）函数。模拟的赤道AAM函数的年变化（包括气压和风的贡献），在90°E分量上与JMA业务分析的结果吻合较好，但在0°分量上与JMA业务分析的结果不一致，这是由于在海洋半球上气压和风的贡献不同。在季节循环中，模拟的水文和海流激发函数加上来自JMA业务分析的AAM函数往往比来自COAGCM输出本身的那些与大地激发函数更一致。由于模拟的海流效应幅度很小，模拟的水文循环被认为是极移非大气年变化的重要贡献者。这证实了水文学作为年度摆动来源的重要性。
[1] The atmospheric, hydrologic, and ocean current contributions to the annual wobble and length-of-day change are investigated, based upon 10 years of monthly values simulated by a coupled ocean-atmosphere general circulation model (COAGCM). Also used are time series of geodetic excitation inferred from the observed wobble in the “SPACE97” data and, for reference, atmospheric angular momentum (AAM) functions from operational objective analysis data of Japan Meteorological Agency (JMA) for the period 1988–1997. The simulated annual variation in equatorial AAM function, which includes pressure and wind contributions, agrees well with that from the JMA operational analysis for 90°E component, but disagrees for 0° component due to differences in both pressure and wind contributions over ocean hemisphere. In the seasonal cycle the simulated hydrologic and ocean current excitation functions plus the AAM function from the JMA operational analysis tend to be in better agreement with the geodetic excitation function than those from the COAGCM output themselves. Because of the small magnitude of the simulated ocean current effects, the simulated hydrological cycle is found to be an important contributor to the nonatmospheric annual variations in polar motion. This confirms the importance of hydrology as a source of the annual wobble.